why this happend using model random?

[Robert Kern]

flyaflya wrote:
> from random import *
> 
> col = [0 for i in range(10)]
> a = [col for  i in range(10)]

This is the problem. The list "a" now has ten references to the same 
object "col". They are not copied.

> seed()
> for i  in range(10):
>      for j in  range(10):
>          a[i][j] = randint(0, 100)

So every time you index into "a[i][j]" you are always getting "col[j]".

-- 
Robert Kern
rkern at ucsd.edu

"In the fields of hell where the grass grows high
  Are the graves of dreams allowed to die."
   -- Richard Harter