[Tutor] optimization: faster than for

Eike Welk eike.welk at gmx.net
Sun Jul 1 19:50:19 CEST 2007

On Sunday 01 July 2007 06:17, elis aeris wrote:
> The for version, as claimed by
> http://www.python.org/doc/essays/list2str.html

The fastest version of the algorithm is this one:

In [4]:import array

In [5]:def f7(list):
   .5.:  return array.array('B', list).tostring()

In [6]:f7([97, 98, 99])

The implicit loop is the "tostring" function. It is written in C and 
it happens to perform the desired algorithm. So there is nothing 
magical about "implicit loops". It just means: Find a library 
function that is written in C and that performs your task.

For manipulating images it means: Find some operations in PIL that do 
what you want, and don't look at pixel values.

Kind regards,

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