Go to a specific line in Python?

I want to go to line 34 in a .txt file and read it. How would you do that in Python?

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Use Python Standard Library’s linecache module:

line = linecache.getline(thefilename, 33)

should do exactly what you want. You don’t even need to open the file — linecache does it all for you!

Method 2

This code will open the file, read the line and print it.

# Open and read file into buffer
f = open(file,"r")
lines = f.readlines()

# If we need to read line 33, and assign it to some variable
x = lines[33]
print(x)

Method 3

A solution that will not read more of the file than necessary is

from itertools import islice
line_number = 34

with open(filename) as f:
    # Adjust index since Python/islice indexes from 0 and the first 
    # line of a file is line 1
    line = next(islice(f, line_number - 1, line_number))

A very straightforward solution is

line_number = 34

with open(filename) as f:
    f.readlines()[line_number - 1]

Method 4

There’s two ways:

1. Read the file, line by line, stop when you’ve gotten to the line you want
2. Use f.readlines() which will read the entire file into memory, and return it as a list of lines, then extract the 34th item from that list.

Solution 1

Benefit: You only keep, in memory, the specific line you want.

code:

for i in xrange(34):
    line = f.readline();
# when you get here, line will be the 34th line, or None, if there wasn't
# enough lines in the file

Solution 2

Benefit: Much less code
Downside: Reads the entire file into memory
Problem: Will crash if less than 34 elements are present in the list, needs error handling

line = f.readlines()[33]

Method 5

You could just read all the lines and index the line your after.

line = open('filename').readlines()[33]

Method 6

for linenum,line in enumerate(open("file")):
    if linenum+1==34: print line.rstrip()

Method 7

I made a thread about this and didn’t receive help so I took matter into my own hands.

Not any complicated code here.

import linecache
#Simply just importing the linecache function to read our line of choosing

number = int(input("Enter a number from 1-10 for a random quote "))
#Asks the user for which number they would like to read(not necessary) 

lines = linecache.getline("Quotes.txt", number)
#Create a new variable in order to grab the specific line, the variable 
#integer can be replaced by any integer of your choosing.

print(lines)
#This will print the line of your choosing.

If you are completing this in python make sure you have both files (.py) and (.txt) in the same location otherwise python will not be able to retrieve this, unless you specify the file location. EG.

linecache.getline("C:/Directory/Folder/Quotes.txt

This is used when the file is in another folder than the .py file you are using.

Hope this helps!

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0