References and copies

[Duncan Booth]

"Larry Bates" <lbates at swamisoft.com> wrote in 
news:ddqdnZ_PjrmN3krd4p2dnA at comcast.com:

> You might try:
> 
> x=n*[n*[' ']]
> 
> But I always question creating arrays this
> way in Python.  It is normally much better
> to start with an empty list and build it as
> you go using .append() method.
> 

Its just as well you question this as it creates a list containing n copies 
of the same list.

A better way to write your example:

   x = [ n*[' '] for i in range(n) ]