CODEWITHSUNDEEP
pythonfilereadline
solarce
solarce

Reputation: 1195

Best method for reading newline delimited files and discarding the newlines?

I am trying to determine the best way to handle getting rid of newlines when reading in newline delimited files in Python.

What I've come up with is the following code, include throwaway code to test.

import os

def getfile(filename,results):
   f = open(filename)
   filecontents = f.readlines()
   for line in filecontents:
     foo = line.strip('\n')
     results.append(foo)
   return results

blahblah = []

getfile('/tmp/foo',blahblah)

for x in blahblah:
    print x

Upvotes: 88

Views: 127903

Answers (7)

Paweł Prażak
Paweł Prażak

Reputation: 3191

What do you think about this approach?

with open(filename) as data:
    datalines = (line.rstrip('\r\n') for line in data)
    for line in datalines:
        ...do something awesome...

Generator expression avoids loading whole file into memory and with ensures closing the file

Upvotes: 13

Curt Hagenlocher
Curt Hagenlocher

Reputation: 20916

lines = open(filename).read().splitlines()

Upvotes: 208

artyom
artyom

Reputation:

Just use generator expressions:

blahblah = (l.rstrip() for l in open(filename))
for x in blahblah:
    print x

Also I want to advise you against reading whole file in memory -- looping over generators is much more efficient on big datasets.

Upvotes: 4

S.Lott
S.Lott

Reputation: 391818

I use this

def cleaned( aFile ):
    for line in aFile:
        yield line.strip()

Then I can do things like this.

lines = list( cleaned( open("file","r") ) )

Or, I can extend cleaned with extra functions to, for example, drop blank lines or skip comment lines or whatever.

Upvotes: 3

routerguy
routerguy

Reputation:

I'd do it like this:

f = open('test.txt')
l = [l for l in f.readlines() if l.strip()]
f.close()
print l

Upvotes: 2

TimoLinna
TimoLinna

Reputation: 241

Here's a generator that does what you requested. In this case, using rstrip is sufficient and slightly faster than strip.

lines = (line.rstrip('\n') for line in open(filename))

However, you'll most likely want to use this to get rid of trailing whitespaces too.

lines = (line.rstrip() for line in open(filename))

Upvotes: 24

David Z
David Z

Reputation: 131550

for line in file('/tmp/foo'):
    print line.strip('\n')

Upvotes: 8

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