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Files in Python Caution about readlines vs. read and split.

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Presentation on theme: "Files in Python Caution about readlines vs. read and split."— Presentation transcript:

1 Files in Python Caution about readlines vs. read and split

2 You would think that lines = infile.readlines() and line = infile.read() lines = line.split(‘\n’) would give the same result in the variable lines, that is, a list of strings from the file, delimited by the newline characters.

3 You would be surprised! readlines() gives you a list of strings, each with a \n at the end Except! if you did not press Enter on the last line of the data file, the last string in the list will not have a \n in it read() followed by split(‘\n’) gives a list of strings, yes, but none of them will have \n in them (remember split removes the delimiters from its results)

4 And another surprise! If you did press Enter on the last line of the data file, readlines still works properly. The last string in the list will have a \n character just like all the others BUT the same file read with the read/split combination will have one extra entry, an empty string at the end of the list This is something you need to be aware of while processing your data – many programs crash because they assume that every string will be the same length, for example.


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