How To Count The Total Number Of Lines In A Text File Using Python

For example if my text file is: blue green yellow black Here there are four lines and now I want to get the result as four. How can I do that?

Solution 1:

You can use sum() with a generator expression:

withopen('data.txt') as f:
    printsum(1for _ in f)

Note that you cannot use len(f), since f is an iterator. _ is a special variable name for throwaway variables, see What is the purpose of the single underscore "_" variable in Python?.

You can use len(f.readlines()), but this will create an additional list in memory, which won't even work on huge files that don't fit in memory.

Solution 2:

This link (How to get line count cheaply in Python?) has lots of potential solutions, but they all ignore one way to make this run considerably faster, namely by using the unbuffered (raw) interface, using bytearrays, and doing your own buffering.

Using a modified version of the timing tool, I believe the following code is faster (and marginally more pythonic) than any of the solutions offered:

def_make_gen(reader):
    b = reader(1024 * 1024)
    while b:
        yield b
        b = reader(1024*1024)

defrawpycount(filename):
    f = open(filename, 'rb')
    f_gen = _make_gen(f.raw.read)
    returnsum( buf.count(b'\n') for buf in f_gen )

Here are my timings:

rawpycount        0.0048  0.0046   1.00
bufcount          0.0074  0.0066   1.43
wccount             0.01    0.01   2.17
itercount          0.014   0.014   3.04
opcount            0.021    0.02   4.43
kylecount          0.023   0.021   4.58
simplecount        0.022   0.022   4.81
mapcount           0.038   0.032   6.82

I would post it there, but I'm a relatively new user to stack exchange and don't have the requisite manna.

EDIT:

This can be done completely with generators expressions in-line using itertools, but it gets pretty weird looking:

from itertools import (takewhile,repeat)

defrawbigcount(filename):
    f = open(filename, 'rb')
    bufgen = takewhile(lambda x: x, (f.raw.read(1024*1024) for _ in repeat(None)))
    returnsum( buf.count(b'\n') for buf in bufgen if buf )

Solution 3:

You can use sum() with a generator expression here. The generator expression will be [1, 1, ...] up to the length of the file. Then we call sum() to add them all together, to get the total count.

withopen('text.txt') as myfile:
    count = sum(1for line in myfile)

It seems by what you have tried that you don't want to include empty lines. You can then do:

withopen('text.txt') as myfile:
    count = sum(1for line in myfile if line.rstrip('\n'))

Solution 4:

count=0withopen ('filename.txt','rb') as f:
    for line in f:
        count+=1print count

Solution 5:

One liner:

total_line_count = sum(1for line inopen("filename.txt"))

print(total_line_count)