reading a file and getting each line of the file separately

Question

I have a text file which has three lines. I want to read those three lines as L1, L2 and L3 and count the character of L1, L2 and L3 as n1, n2 and n3. I tried as follows:

     f=open(sys.argv[1],'r')
     L1=f.readline()   
     L2=f.readline()   
     L3=f.readline()  
     if L1[-1]=='\n': L1=L1[:len(L1)-1] 
     if L2[-1]=='\n': L2=L2[:len(L2)-1] 
     if L3[-1]=='\n': L3=L3[:len(L3)-1] 
     n1=len(L1); n2=len(L2); n3=len(L3) 
     print L1, n1, L2, n2, L3, n3

The above script is working fine. But I wanted to know if there is a better/easier way to get L1, L2 and L3. Thanks in advance!

score 1 · Answer 1 · answered Sep 27 '13 at 06:26

You could:

Add exception handling using try-catch IOError for any problem opening the file and reading from it. See Errors and Exceptions Tutorial - or use the with statement for newer versions of Python as suggested by other answers.
Add exception handling using try-catch IndexError to handle the case where not enough arguments are given.
Do the check for newline with string.rstrip or string.strip for brevity.
Store the values in an array as suggested by other answers (you might want to terminate after 3 lines in case you get the wrong file and end up reading a very large file into memory).

score 1 · Accepted Answer · answered Sep 27 '13 at 06:38

1

How about this:

with open(sys.argv[1]) as f:
  L1, L2, L3 = (line.rstrip() for line in f.readlines()[:3])

But you should really use lists...

answered Sep 27 '13 at 06:38

erlc

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score 0 · Answer 3 · answered Sep 27 '13 at 06:15

0

The best way in my opinion is try putting them in an array. I dont use python but thats what ill do in c++

answered Sep 27 '13 at 06:15

PopperJuan

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Greg · Answer 4 · 2013-09-27T06:32:00.280

0

sure..

lines = []
with open(sys.argv[1], "r") as file:
    for line in file.readlines():
        if line[-1] == "\n":
            line = line[:-1]
        lines.append(line)

This way it doesn't matter how many lines you have in your file. Your program will still run until the end

edited Sep 27 '13 at 06:32

answered Sep 27 '13 at 06:15

Greg

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score 0 · Answer 5 · edited May 23 '17 at 12:29

0

I searched in stackoverflow and found a code that is simpler. It saves the content into an array:

with open(fname) as f:
    content = f.readlines()

If you want to strip the \n:

with open(fname) as f:
    content = [line.strip() for line in f]

edited May 23 '17 at 12:29

Community

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answered Sep 27 '13 at 06:18

cwhy

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reading a file and getting each line of the file separately

5 Answers5