Reading ints line from a file in Python

  • 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

  • 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.)


    Thx for your answer :) I didn't think of using map here.

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Content dated before 7/24/2021 11:53 AM

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