How to iterate over every n-th line from a file?
Solved
Development Troubleshooting
-
I have a file called data.txt containing lines of data:
This is line one This is line two This is line three This is line four This is line five This is line six This is line seven
…
I have the following code:with open('data.txt', 'r') as f: for x, line in enumerate(f): if x == 3: print(line) In this case it only prints
“This is line four”.
I do understand why but how do I take it from here and have it print the lines 4, 7, 10, 13, …? -
Demo:
data.txt:
line1 line2 line3 line4 line5 line6 line7 line8 line9 line10 line11 line12 line13
Code:
from itertools import islice with open('data.txt') as f: for line in islice(f, 3, None, 3): print line, # Python3: print(line, end='')
Produces:
line4 line7 line10 line13