CODEWITHSUNDEEP
pythonfile
cybergoof
cybergoof

Reputation: 1437

How to better read lines of a file in python

Is there a more python friendly way to read 100 lines from a file, other than this way:

  f=open(varFilename,"r")
  count=0
  for fileLine in f:
      print fileLine
      count+=1
      if count>100:
          break

I just feel like there is a better way than having a count increment and then try and break inside the loop.

Upvotes: 0

Views: 398

Answers (2)

Martijn Pieters
Martijn Pieters

Reputation: 1122082

Use itertools.islice() to limit the file object iterator to just 100 lines:

from itertools import islice

with open(filename) as f:
    for line in islice(f, 100):

Here I'm also using the file object as a context manager; the with statement ensures the file is closed again when the code block is exited.

If you don't need to limit the number of itertions but only need a counter in a loop, don't use a separate counter. Use enumerate() instead:

for i, line in enumerate(f):
    if i > 100:

Upvotes: 8

Ashwini Chaudhary
Ashwini Chaudhary

Reputation: 250961

You can use itertools.islice to get just the first n lines from file object:

from itertools import islice

with open(varFilename) as f:
    for line in islice(f, 10):
        #do something here

And use with statement while handling files:

It is good practice to use the with keyword when dealing with file objects. This has the advantage that the file is properly closed after its suite finishes, even if an exception is raised on the way.

Upvotes: 6

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