The path and simple file reading - Revision history

WikiSysop: /* Exercises to be handed in */

2025-10-03T13:52:17Z

Exercises to be handed in

← Older revision		Revision as of 15:52, 3 October 2025
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	== Exercises to be handed in ==		== Exercises to be handed in ==
	Again, any use of list is a fail. Why? Because it is overkill and too memory consuming for these kind of tasks. It is also good thinking practice.		Again, any use of list is a fail. Why? Because it is overkill and too memory consuming for these kind of tasks. It is also good thinking practice.
	# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat'', which you have put in the same folder as the program. Then you just give the file name and not the full path. There are 1675 lines.
	# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns. BTW, the file name can be the full path or a relative path if the file is not in the same folder as the program.		# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat'', which you have put in the same folder as the program. Then you just give the file name and not the full path. There are 1675 lines.<br><br>
	# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: The '''None''' built-in no-value could be useful. The max in ''ex1_1.dat'' is 10.4155.		# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns. BTW, the file name can be the full path or a relative path if the file is not in the same folder as the program.<br><br>
	# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.		# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: The '''None''' built-in no-value could be useful. The max in ''ex1_1.dat'' is 10.4155.<br><br>
	# Move or copy ''mixedlines.txt'' to some other folder for testing with this program. Write a program that asks for just a file name and then adds the full (or relative) path (stored in a variable like a constant) to the file name and then opens file and count the number of empty lines and non-empty lines in the file. Display the two counts. <br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.<br><br>
			# Move or copy ''mixedlines.txt'' to some other folder for testing with this program. Write a program that asks for just a file name and then adds the full (or relative) path (stored in a variable like a constant) to the file name and then opens file and count the number of empty lines and non-empty lines in the file. Display the two counts. <br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.<br><br>
	# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.<br>Using the file ''ex1_1.dat'' and the target number 0, the 2 sums are; -1523.1255 and 618.7112.		# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.<br>Using the file ''ex1_1.dat'' and the target number 0, the 2 sums are; -1523.1255 and 618.7112.

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

WikiSysop at 11:27, 27 August 2025

2025-08-27T11:27:06Z

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WikiSysop: /* Exercises to be handed in */

2025-08-27T09:24:32Z

Exercises to be handed in

← Older revision		Revision as of 11:24, 27 August 2025
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	# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.
	# Move or copy ''mixedlines.txt'' to some other folder for testing with this program. Write a program that asks for just a file name and then adds the full (or relative) path (stored in a variable like a constant) to the file name and then opens file and count the number of empty lines and non-empty lines in the file. Display the two counts. <br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.		# Move or copy ''mixedlines.txt'' to some other folder for testing with this program. Write a program that asks for just a file name and then adds the full (or relative) path (stored in a variable like a constant) to the file name and then opens file and count the number of empty lines and non-empty lines in the file. Display the two counts. <br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.
	# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.		# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.<br>Using the file ''ex1_1.dat'' and the target number 0, the 2 sums are; -1523.1255 and 618.7112.

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

WikiSysop: /* Exercises to be handed in */

2025-08-27T08:13:04Z

Exercises to be handed in

← Older revision		Revision as of 10:13, 27 August 2025
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	== Exercises to be handed in ==		== Exercises to be handed in ==
	Again, any use of list is a fail. Why? Because it is overkill and too memory consuming for these kind of tasks. It is also good thinking practice.		Again, any use of list is a fail. Why? Because it is overkill and too memory consuming for these kind of tasks. It is also good thinking practice.
	# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.		# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat'', which you have put in the same folder as the program. Then you just give the file name and not the full path. There are 1675 lines.
	# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.		# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns. BTW, the file name can be the full path or a relative path if the file is not in the same folder as the program.
	# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: The '''None''' built-in no-value could be useful. The max in ''ex1_1.dat'' is 10.4155.		# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: The '''None''' built-in no-value could be useful. The max in ''ex1_1.dat'' is 10.4155.
	# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.
	# Write a program that asks for a file name and then ~~open~~ the file and count the number of empty lines and non-empty lines in the file. Display the two counts~~. Test it on the ''mixedlines.txt'' file~~.<br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.		# Move or copy ''mixedlines.txt'' to some other folder for testing with this program. Write a program that asks for just a file name and then adds the full (or relative) path (stored in a variable like a constant) to the file name and then opens file and count the number of empty lines and non-empty lines in the file. Display the two counts. <br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.
	# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.		# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.

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

WikiSysop at 15:30, 25 August 2025

2025-08-25T15:30:45Z

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	== Required course material for the lesson ==		== Required course material for the lesson ==

WikiSysop: /* Exercises to be handed in */

2025-08-25T15:26:38Z

Exercises to be handed in

← Older revision		Revision as of 17:26, 25 August 2025
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	# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.		# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.
	# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.		# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.
	# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.		# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: The '''None''' built-in no-value could be useful. The max in ''ex1_1.dat'' is 10.4155.
	# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.
	# Write a program that asks for a file name and then open the file and count the number of empty lines and non-empty lines in the file. Display the two counts. Test it on the ''mixedlines.txt'' file.<br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.		# Write a program that asks for a file name and then open the file and count the number of empty lines and non-empty lines in the file. Display the two counts. Test it on the ''mixedlines.txt'' file.<br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.

WikiSysop: /* Exercises to be handed in */

2025-08-25T15:25:46Z

Exercises to be handed in

← Older revision		Revision as of 17:25, 25 August 2025
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	# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.		# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.
	# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.
			# Write a program that asks for a file name and then open the file and count the number of empty lines and non-empty lines in the file. Display the two counts. Test it on the ''mixedlines.txt'' file.<br>Warning: Just because you can not see it, it does not mean it does not exists. Invisible characters have long been a curse of programmers. So do not make them yourself. Hint: ''mixedlines.txt'' has 19 empty lines and 66 non-empty lines.
			# Ask for a number - this is your target number. Now ask for a filename - ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat'' are good options. Open the file and compute two sums from the numbers in the file; the sum of the numbers that are higher than your target number and the sum of the numbers that are lower than your target number. Any number in the file that is equal to your target number is ignored. Display the result.

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

WikiSysop at 15:10, 25 August 2025

2025-08-25T15:10:22Z

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	== Subjects covered ==		== Subjects covered ==
			The file system, folder hierarchies, the path & the library os.path<br>
	''with'' statement, just a simple use of it.<br>		''with'' statement, just a simple use of it.<br>
	''open'' function for opening files for access. ~~Filehandles~~.<br>		''open'' and ''close'' function for opening and closing files for access. File handles.<br>
	~~Built-in values; ''True'', ''False''~~ and ~~''None''~~.<br>		Reading and writing files.<br>
	~~Loop control with ''continue'' and ''break'' and how NOT to use them.~~

	== Advice ==		== Advice ==
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	== Exercises to be handed in ==		== Exercises to be handed in ==
	~~# Write~~ a ~~program that reads the file ''ex1.acc'' and displays it on the screen~~. ~~Display it '''correctly''' as~~ it is~~, i.e. the OUTPUT~~ of ~~your print should look precisely like the original file~~. ~~Hint: look at the spacing between lines~~.		Again, any use of list is a fail. Why? Because it is overkill and too memory consuming for these kind of tasks. It is also good thinking practice.
	# ~~Make the~~ program ~~ask~~ for a ~~filename (the input~~ file ~~in the following exercises),~~ and ~~display the file on the screen.~~		# Construct a program first asks for a file name and subsequently counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.
	~~# Construct a program that~~ counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.		# Have you wondered how the '''sum()''' function works? Wonder no longer. Make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.
	# ~~Now make~~ a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.		# Did you also wonder about the '''max()''' function? Make a program that finds the maximum number in a file. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.
	# ~~Based on~~ the ~~previous program, now make a new one that calculates the mean value of the columns. Create your own test file with some numbers~~ (~~where you know what the result should be~~) ~~and feed that to the program.~~		# Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.<br>For extra difficulty, make the program only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word.
	~~# Now make a program that counts the number of positive and negative numbers in an input file. Also count the zeroes in the column, if there are any. Display the result.~~
	~~# Now make~~ a program that finds the maximum number in a ~~column~~. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.
	# ~~Now make~~ a ~~program that finds the minimum~~ number in a ~~column and display the result~~. ~~The max in~~ ''~~ex1_3~~.~~dat~~'' ~~is -4~~.~~3967~~. ~~Hint: What happens~~ if ~~all~~ the ~~numbers~~ in the file ~~are positive~~.
	~~# It begins to get trivial~~. ~~Now make~~ a ~~program that does all of~~ the ~~above~~, ~~that is; calculate~~ the ~~sum~~, the ~~number of lines~~, ~~the mean value~~, the number ~~of positive, negative and zero numbers, the maximum and the minimum value. You can only read the file once. Display the all results clearly so there is no doubt about what you display~~.

	== Exercises for extra practice ==		== Exercises for extra practice ==
	* Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.
	* For extra difficulty, do the same program once more, but this time, it should only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word. If you already solved this in above exercise - good for you.
	* Ask for 2 integers. Now print the first 20 numbers of the [https://en.wikipedia.org/wiki/Fibonacci_number Fibonacci sequence] given by those numbers. If the input is 1 & 3, the output would be 1 3 4 7 11 18 29 47 etc.. The next number is the sum of the 2 previous.

WikiSysop: Created page with "NOTOC {| width=500 style="float:right; margin-left: 10px; margin-top: -56px;" |Previous: Python Recap |Next: Pseudocode and Comments |} == Required course material for the lesson == Powerpoint: [https://teaching.healthtech.dtu.dk/material/22116/22116_02-PathFile.ppt The path & simple file reading]
Resource: Example code - File Reading
== Subjects covered == ''with'' statement, just a simple use of it.
''open'' function for opening files for..."

2025-08-25T14:49:47Z

Created page with "__NOTOC__ {| width=500 style="float:right; margin-left: 10px; margin-top: -56px;" |Previous: Python Recap |Next: Pseudocode and Comments |} == Required course material for the lesson == Powerpoint: [https://teaching.healthtech.dtu.dk/material/22116/22116_02-PathFile.ppt The path & simple file reading] Resource: Example code - File Reading == Subjects covered == ''with'' statement, just a simple use of it. ''open'' function for opening files for..."

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__NOTOC__
{| width=500 style="float:right; margin-left: 10px; margin-top: -56px;"
|Previous: [[Python Recap]]
|Next: [[Pseudocode and Comments]]
|}
== Required course material for the lesson ==
Powerpoint: [https://teaching.healthtech.dtu.dk/material/22116/22116_02-PathFile.ppt The path & simple file reading] 
Resource: [[Example code - File Reading]] 

== Subjects covered ==
''with'' statement, just a simple use of it. 
''open'' function for opening files for access. Filehandles. 
Built-in values; ''True'', ''False'' and ''None''. 
Loop control with ''continue'' and ''break'' and how NOT to use them.

== Advice ==
You might want to consider what would happen if you feed an empty file to your program. 
Are you looking for files? See the top line of the [[Programme]] page.

== Exercises to be handed in ==
# Write a program that reads the file ''ex1.acc'' and displays it on the screen. Display it '''correctly''' as it is, i.e. the OUTPUT of your print should look precisely like the original file. Hint: look at the spacing between lines.
# Make the program ask for a filename (the input file in the following exercises), and display the file on the screen.
# Construct a program that counts the number of lines in the input file, and displays the result. Try it with the file ''ex1.dat''. There are 1675 lines.
# Now make a Python program that sums numbers from ONE input file and displays the sum of the numbers. I have created 3 input files with the columns from ''ex1.dat''; ''ex1_1.dat'', ''ex1_2.dat'' & ''ex1_3.dat''. Use the 3 files as input ONE AT A TIME and see the sums. The sums are approx. Col 1; -904.4143, Col 2; 482.8410, Col 3; 292.05150 for the three columns.
# Based on the previous program, now make a new one that calculates the mean value of the columns. Create your own test file with some numbers (where you know what the result should be) and feed that to the program.
# Now make a program that counts the number of positive and negative numbers in an input file. Also count the zeroes in the column, if there are any. Display the result.
# Now make a program that finds the maximum number in a column. Display the result. This is quite tricky. Hint: '''None''' could be useful. The max in ''ex1_1.dat'' is 10.4155.
# Now make a program that finds the minimum number in a column and display the result. The max in ''ex1_3.dat'' is -4.3967. Hint: What happens if all the numbers in the file are positive.
# It begins to get trivial. Now make a program that does all of the above, that is; calculate the sum, the number of lines, the mean value, the number of positive, negative and zero numbers, the maximum and the minimum value. You can only read the file once. Display the all results clearly so there is no doubt about what you display.

== Exercises for extra practice ==
* Ask for some input - it could be a word or a number or a sentence. Then ask for a file name - any file will do, but ''mixedlines.txt'' or ''ex5.acc'' are good. Now read the file and determine if one (or more) of the lines in the file matches your input precisely. Display "Match" or "No match" accordingly. Hint: A line from a file has a newline at the end, but using the '''input''' function does not result in this newline.
* For extra difficulty, do the same program once more, but this time, it should only say "Match" or "No match" once, no matter how many matches there are. Make your own test file, with lots of the same number or word. If you already solved this in above exercise - good for you.
* Ask for 2 integers. Now print the first 20 numbers of the [https://en.wikipedia.org/wiki/Fibonacci_number Fibonacci sequence] given by those numbers. If the input is 1 & 3, the output would be 1 3 4 7 11 18 29 47 etc.. The next number is the sum of the 2 previous.