Intermediate classes - Revision history

WikiSysop: /* Exercises to be handed in */

2026-03-23T10:06:12Z

Exercises to be handed in

← Older revision		Revision as of 12:06, 23 March 2026
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	The first four exercises will continue with the '''Fasta''' class from last time.		The first four exercises will continue with the '''Fasta''' class from last time.
	# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>		# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>
	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element at 5, so the next one is at 8. You are free to make your own decision - just be clear about it. ~~Just realize~~ if you insert something because you see a special ~~elements~~ and you do not choose my way, then you will create an infinite loop, since you will see the special element again.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element at 5, so the next one is at 8. You are free to make your own decision - just be clear about it. Realize if you insert something because you see a special element and you do not choose my way, then you will create an infinite loop, since you will see the special element again.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__''']. Try with the files ''dna7.fsa'' and ''protein.fsa''. That will be a strange DNA and protein mix, but it is a great opportunity to use the '''discard''' method to get rid of one of the types.<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__''']. Try with the files ''dna7.fsa'' and ''protein.fsa''. That will be a strange DNA and protein mix, but it is a great opportunity to use the '''discard''' method to get rid of one of the types.<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>

WikiSysop: /* Exercises to be handed in */

2026-03-23T10:05:41Z

Exercises to be handed in

← Older revision		Revision as of 12:05, 23 March 2026
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	The first four exercises will continue with the '''Fasta''' class from last time.		The first four exercises will continue with the '''Fasta''' class from last time.
	# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>		# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>
	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ~~ant~~ 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element at 5, so the next one is at 8. You are free to make your own decision - just be clear about it. Just realize if you insert something because you see a special elements and you do not choose my way, then you will create an infinite loop, since you will see the special element again.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__''']. Try with the files ''dna7.fsa'' and ''protein.fsa''. That will be a strange DNA and protein mix, but it is a great opportunity to use the '''discard''' method to get rid of one of the types.<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__''']. Try with the files ''dna7.fsa'' and ''protein.fsa''. That will be a strange DNA and protein mix, but it is a great opportunity to use the '''discard''' method to get rid of one of the types.<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>

WikiSysop: /* Required course material for the lesson */

2026-03-19T16:00:12Z

Required course material for the lesson

← Older revision		Revision as of 18:00, 19 March 2026
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	== Required course material for the lesson ==		== Required course material for the lesson ==
	Powerpoint: [https://teaching.healthtech.dtu.dk/material/22118/22118_07-Classes.ppt Classes]<br>		Powerpoint: [https://teaching.healthtech.dtu.dk/material/22118/22118_07-Classes.ppt Classes]<br>
	Resource: [[Example code - ~~Classes~~]]<br>		Resource: [[Example code - Inheritance issues]]<br>

	== Subjects covered ==		== Subjects covered ==

WikiSysop: /* Exercises to be handed in */

2026-03-18T22:06:42Z

Exercises to be handed in

← Older revision		Revision as of 00:06, 19 March 2026
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	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>
	# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>		# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>
	# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading.		# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading - the normal arithmetic operator used on numbers are used on something completely different.

	== Exercises for extra practice ==		== Exercises for extra practice ==
	# You continue to add the unique identifier control for all methods in Fasta and FastaSet, as mentioned last week.		# You continue to add the unique identifier control for all methods in Fasta and FastaSet, as mentioned last week.

WikiSysop: /* Exercises to be handed in */

2026-03-18T16:47:37Z

Exercises to be handed in

← Older revision		Revision as of 18:47, 18 March 2026
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	# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>		# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>
	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ant 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ant 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__''']. Try with the files ''dna7.fsa'' and ''protein.fsa''. That will be a strange DNA and protein mix, but it is a great opportunity to use the '''discard''' method to get rid of one of the types.<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>
	# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>		# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>

WikiSysop: /* Exercises to be handed in */

2026-03-18T14:59:54Z

Exercises to be handed in

← Older revision		Revision as of 16:59, 18 March 2026
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	The first four exercises will continue with the '''Fasta''' class from last time.		The first four exercises will continue with the '''Fasta''' class from last time.
	# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>		# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>
	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When ~~iteration~~ over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ant 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iterating over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ant 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>

WikiSysop: /* Exercises to be handed in */

2026-03-18T14:59:31Z

Exercises to be handed in

← Older revision		Revision as of 16:59, 18 March 2026
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	The first four exercises will continue with the '''Fasta''' class from last time.		The first four exercises will continue with the '''Fasta''' class from last time.
	# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>		# Use magic methods to add ''iteration'' and ''length'' evaluation (using '''__iter__''' and '''__len__''' magic methods) to the '''Fasta''' class. Do this so you can write code like <div style="font-family:'Courier New'">if len(MyFastaInstance) > 0:<br>    for header, sequence in MyFastaInstance:<br>        # Do something with header and sequence<br>        print(header, sequence)</div>The function '''len''' returns the number of sequences.<br><br>
	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise. You need to take a position on this issue: When iteration over entries, how should you continue after inserting entries at your current position? Example: You are at element in position 5, you insert 2 elements at that position. This WILL mean the new elements are at position 5 and 6, and the one you "looked at" is now on position 7. Do you continue the iteration on position 5 or is the next position 8? My opinion is that you should not look at the new elements and you have already looked at the "old" element ant 5, so the next one is at 8. You are free to make your own decision - just be clear about it.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>

WikiSysop: /* Exercises for extra practice */

2026-03-18T09:06:30Z

Exercises for extra practice

← Older revision		Revision as of 11:06, 18 March 2026
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	== Exercises for extra practice ==		== Exercises for extra practice ==
			# You continue to add the unique identifier control for all methods in Fasta and FastaSet, as mentioned last week.

WikiSysop: /* Exercises to be handed in */

2026-03-17T15:12:09Z

Exercises to be handed in

← Older revision		Revision as of 17:12, 17 March 2026
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	# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise.<br><br>		# Add the methods '''deletethis()''', '''insertthis(header, sequence)''', '''verifythis(alphabet)''' and '''discardthis(alphabet)''' to the '''Fasta''' class. The methods should only work when ''iterating over an instance at the current item'', i.e. they work when you are iterating over the fasta sequences on the ''current'' sequence and header, like this:<div style="font-family:'Courier New'">for header, sequence in MyFastaInstance:<br>    if not MyFastaInstance.verifythis("DNA"):<br>        MyFastaInstance.deletethis()<br>        continue<br>    # Do something with header and sequence</div>As some may remember, it is normally impossible to successfully iterate straightforward through a list and delete and/or add elements to the list during the iteration. You have to make this possible. Hint: change the way your iteration works in the previous exercise.<br><br>
	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor. Now that the Fasta class is done, save it in a file, so you can import it for the next exercises.<br><br>
	# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>		# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>
	# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading.		# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading.

	== Exercises for extra practice ==		== Exercises for extra practice ==

WikiSysop: /* Exercises to be handed in */

2026-03-17T15:08:27Z

Exercises to be handed in

← Older revision		Revision as of 17:08, 17 March 2026
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	# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>		# Let's do something natural. Make it possible to add one FastaInstance to another using the '''+=''' operator, like this:<div style="font-family:'Courier New'">FastaInstance1 += FastaInstance2<br></div>The headers and sequences in Fastainstance2 should be added (list extension) to the headers and sequences in FastaInstance1. Use the magic method [https://zetcode.com/python/dunder-iadd/ '''__iadd__'''].<br><br>
	# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor.<br><br>		# Implement the ''addition'', using [https://zetcode.com/python/dunder-add/ '''__add__''']. Addition creates a new Fasta instance, but leaves the originals untouched.<div style="font-family:'Courier New'">FastaInstance3 = FastaInstance1 + FastaInstance2<br></div>The resulting Fasta object must contain the headers and sequences from FastaInstance1 and FastaInstance2 in that order. Note that this works as an alternative constructor.<br><br>
	# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content'''.<br>F) Override the '''discard''' method in a similar way to '''content'''.<br><br>		# You can consider a '''Fasta''' instance as a ''set'' of headers/sequences. The sequences are obviously uniquely identified by the identifier in the header, which is what will be used as key in the set operations. In the rest of the exercises we will explore inheritance by making a new class called '''FastaSet''', which inherits from the '''Fasta''' class.<br>A) The original '''__init__''', '''save''', '''load''', '''insert''', the iteration and the corresponding '''deletethis''', '''insertthis''', '''verifythis''' and '''discardthis''' methods are fine to keep in the new class (meaning do nothing about them).<br>B) To help in the new class create a new getter method '''identifiers''', which returns a list of identifiers from the header lines.<br>C) Override the '''content''' method such that it takes a set or list of identifiers and returns only the headers/sequences that corresponds to the identifiers in the list. If you do not specify a list/set of identifiers, it still returns all.<br>D) Override the '''delete''' method in a similar way - it deletes the headers/sequences that corresponds to the input.<br>E) Override the '''verify''' method in a similar way to '''content''' - it verifies the headers/sequences that corresponds to the input.<br>F) Override the '''discard''' method in a similar way to '''content''' - it discards the headers/sequences that corresponds to the input.<br><br>
	# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading.		# As the new FastaSet class is set orientated, implement the following set operations in the class:<br>A) union, operator is '''\|''', magic method is '''__or__'''.<br>B) intersection, operator is '''&''', magic method is '''__and__'''.<br>C) difference, operator is '''-''', magic method is '''__sub__'''.<br>D) symmetric difference, operator is '''^''', magic method is '''__xor__'''.<br>These are quite similar to the addition in exercise 4 - the operators are used in the same way and a new Fasta object is returned. The identity of the sequence depends on the identifier in the corresponding header. This is an example of operator overloading.

	== Exercises for extra practice ==		== Exercises for extra practice ==