[pygame] bidimensional arrays or the quick way to maps

[pistacchio <pistacchio@xxxxxxxxx>]

maps are certainly a very common feature in game development. the 
easiest way to trace maps (and the one that i've used in other languages 
in tha past) is to use multidimensional arrays. so, a tile-map, can be 
stored and worked on as a simple array (or list) that goes like this:

tile_map[x][y] = tile_number

now, probably i'm missing a basic feature of python, but it seems to 
lack of a native support for multidimensional arrays.  i've seen that 
NumPy as an advanced array class, but probably so advanced that i got 
lost in the documentation and i could't find a way to get the simple 
things i need:
-declare a multidimensional array specifiying the lenght of each 
dimension (like, to obtain a 10x20 grid a sort of  "a = array(10,20)" or 
(9,19) if 0-based)
-easily access the cells for reading / appending / writing data, like in 
"a[7][4] =  8" to alter or set the content of a given cell.

how did you solve the problem?
thanks in advance
gustavo