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I have to list a integers from a text file separated by newlines into a python list. I ended up with the code above which works (for my case) but certainly is far form optimal.

def readIntegers(pathToFile): f = open(pathToFile) contents = f.read() f.close() tmpStr = "" integers = [] for char in contents: if char == '\r': integers.append(int(tmpStr)) tmpStr = "" continue if char == '\n': continue tmpStr += char return integers

Now I have much less code, but I'm not sure for which cases split() works correctly.

def readIntegers(pathToFile): with open(pathToFile) as f: a = [int(x) for x in f.read().split()] return a
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1 Answer 1

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No need for split (you can use readlines). But no need for readlines, for that matter:

def read_integers(filename): with open(filename) as f: return map(int, f)

or, if that’s more to your fancy:

def read_integers(filename): with open(filename) as f: return [int(x) for x in f]

A file object is simply iterable in Python, and iterates over its lines.

Note that, contrary to what I said earlier, wrapping the file object in a with block is highly recommended. Python doesn’t actually guarantee (although it recommends it) that objects are disposed of automatically at the end of the scope. Worse, it’s not guaranteed that a file object that is collected actually closes the underlying stream.

(Note that I’ve adapted the method name to Python conventions.)

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  • \$\begingroup\$ Thx for your answer :) I didn't think of using map here. \$\endgroup\$ Commented Jun 11, 2012 at 6:02

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