[Tutor] optimization: faster than for

[Eike Welk]

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()
   .5.:

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


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,
Eike.