Skip First Couple of Lines While Reading Lines in Python File

Skip first couple of lines while reading lines in Python file

Use a slice, like below:

with open('yourfile.txt') as f:
    lines_after_17 = f.readlines()[17:]

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If the file is too big to load in memory:

with open('yourfile.txt') as f:
    for _ in range(17):
        next(f)
    for line in f:
        # do stuff

how to skip certain line in text file and keep reading the next line in python?

It's not necessary to add an if else statement in for loop, so you can modify your code in this way:

f = open("test.txt", "r")
word = "man"
for line in f:
    if not word in line:
        print line

Furthermore, the issue in your code is that you are using f.next() directly in a for loop used to scan the file. This is the reason because when the line contains "man" word, your code skips two lines.

If you want preserve if else statement because this is only an example of a more complex problem, you can use the following code:

f = open("test.txt", "r")
word = "man"
for line in f:
    if word in line:
        continue
    else:
        print line

Using continue, you skip one loop's iteration, and so you can reach your goal.

As Alex Fung suggests, would be better use with, so your code would become like this:

with open("test.txt", "r") as test_file:
    for line in test_file:
        if "man" not in line:
            print line

Want to skip last and first 5 lines while reading file in python

You could use a neat feature of slicing, you can count from the end with negative slice index, (see also this question):

lines = f.readlines()[5:-5]

just make sure there are more than 10 lines:

all_lines = f.readlines()
lines = [] if len(all_lines) <= 10 else all_lines[5:-5]

(this is called a ternary operator)

How to skip 2 lines in a file with Python?

I usually use next() when I want to skip a single line, usually a header for a file.

with open(file_path) as f:
    next(f) # skip 1 line
    next(f) # skip another one.
    for line in f:
        pass # now you can keep reading as if there was no first or second line.

Note: In Python 2.6 or earlier you must use f.next()

python pandas read text file, skip particular lines

Here is an attempt to 'craft magic'. The idea is to try read_csv with different skiprows until it works

import pandas as pd
from io import StringIO
data = StringIO(
'''
========================================= 
hello 123
========================================= 
Dir: /x/y/z/RTchoice/release001/data 
Date: 17-Mar-2020 10:0:08 
Output File: /a/b/c/filename.txt 
N: 2842
-----------------------------------------
Subject col1    col2    col3    
001 10.00000    1.00000 3.00000 
002 11.00000    2.00000 4.00000
''')

for n in range(1000):
    try:
        data.seek(0)
        df = pd.read_csv(data, delimiter = "\s+", skiprows=n)
    except:
        print(f'skiprows = {n} failed (exception)')   
    else:
        if len(df.columns) == 1: # do not let it get away with a single-column df
            print(f'skiprows = {n} failed (single column)')
        else:   
            break
print('\n', df)

output:

skiprows = 0 failed (exception)
skiprows = 1 failed (exception)
skiprows = 2 failed (exception)
skiprows = 3 failed (exception)
skiprows = 4 failed (exception)
skiprows = 5 failed (exception)
skiprows = 6 failed (exception)
skiprows = 7 failed (exception)
skiprows = 8 failed (single column)

    Subject  col1  col2  col3
0        1  10.0   1.0   3.0
1        2  11.0   2.0   4.0

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