Demo:
data.txt:
line1 line2 line3 line4 line5 line6 line7 line8 line9 line10 line11 line12 line13Code:
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 line13Reff