Questions: While And List Comprehension

MRAB python at mrabarnett.plus.com
Thu Nov 11 02:38:49 CET 2010


On 11/11/2010 00:29, James Mills wrote:
> On Thu, Nov 11, 2010 at 8:56 AM, Emile van Sebille<emile at fenx.com>  wrote:
>> Easiest would be print [ v for v in sys.stdin.readlines()[:5] ] but that
>> still reads the entire sys.stdin (whatever it may be...)
>
> Here's a way of doing the same thing without consuming the entire
> stream (sys.stdin):
>
> #!/usr/bin/env python
>
> import sys
> print [v for v in list(line for line in sys.stdin)[:5]]
>
> This uses a generator expression to read from stdin, converts this to
> a list (only getting the first 5 items).
>
'list' will exhaust the input, then the slicing will return at most 5
lines.



More information about the Python-list mailing list