Reading specific lines only

Question

I\'m using a for loop to read a file, but I only want to read specific lines, say line #26 and #30. Is there any built-in feature to achieve this?

Thanks

Answer 1

I prefer this approach because it's more general-purpose, i.e. you can use it on a file, on the result of f.readlines(), on a StringIO object, whatever:

def read_specific_lines(file, lines_to_read):
   """file is any iterable; lines_to_read is an iterable containing int values"""
   lines = set(lines_to_read)
   last = max(lines)
   for n, line in enumerate(file):
      if n + 1 in lines:
          yield line
      if n + 1 > last:
          return

>>> with open(r'c:\temp\words.txt') as f:
        [s for s in read_specific_lines(f, [1, 2, 3, 1000])]
['A\n', 'a\n', 'aa\n', 'accordant\n']