Questions: While And List Comprehension

MRAB python at
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>  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

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