difference between readlines() and split() [python]

Question

imagine we have a file = open("filetext.txt", 'r')

what is the difference between the split() method and the readlines() method
It seems that both split each line and put it as a string in a list.
so what makes them different ?

for line in file:
    values = line.split()     #break each line into a list

file.readlines()  #return a list of strings each represent a single line in the file

Asked By: Mozein

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Source

Answer 1

This is the main difference:

A file object has readlines but not split:

>>> print hasattr(file, 'split')
False
>>> print hasattr(file, 'readlines')
True

A str object has split but not readlines:

>>> hasattr("somestring", 'split')
True
>>> hasattr("somestring", 'readlines')
False

And to answer your question, one is operating on a string object and one is operating on a file object.

They don’t do the same thing since one returns a list of lines when operating on a file and one returns a split line when operating on a string.

Answered By: Reut Sharabani

Answer 2

readlines splits the entire file into lines and is nearly equivalent to file.read().split('n'), except that the latter will remove new lines, whereas readlines by itself will retain new lines.

Your example,

for line in file:
    values = line.split()

splits each line by its spaces, building a list of words in the line. value is overwritten on each iteration so unless you save values somewhere, only parts of the file are in-memory at a single time.

Answered By: tdelaney

Answer 3

readlines does platform agnostic line splitting and split does generic splitting.

As an example:

In [1]: from StringIO import StringIO

In [2]: StringIO('test:test:test').readlines()
Out[2]: ['test:test:test']

In [3]: StringIO('test:test:test').read().split(':')
Out[3]: ['test', 'test', 'test']

Answered By: ferhatelmas

difference between readlines() and split() [python]

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