python; multidimensional "arrays"

horacioemilio · 12-06-2007, 09:30 AM

in python, when I want to use arrays, I follow this way;

DATA = [0] * nint

and when I want to use I do;

....

DATA[i] = ....

do you know how to do similar but in two dimensions ?

thanks

ghostdog74 · 12-06-2007, 05:49 PM

maybe this

Code:

>>> e = [[0] * 3]*3
>>> e
[[0, 0, 0], [0, 0, 0], [0, 0, 0]]

paddy3118 · 12-07-2007, 03:03 PM

Quote:

Originally Posted by ghostdog74

maybe this

Code:

>>> e = [[0] * 3]*3
>>> e
[[0, 0, 0], [0, 0, 0], [0, 0, 0]]

You would duplicate references to the same list if you did the above.

Here is an example:

Code:

>>> e = [[0] * 3]*3
>>> e
[[0, 0, 0], [0, 0, 0], [0, 0, 0]]
>>> e[0][1]
0
>>> e[0][1] =3.141
>>> e
[[0, 3.141, 0], [0, 3.141, 0], [0, 3.141, 0]]

Instead create a list of lists without duplicate references. Here is one way:

Code:

>>> e = [[[] for inner in range(3)] for outer in range(4)]
>>> e
[[[], [], []], [[], [], []], [[], [], []], [[], [], []]]
>>> len(e)
4
>>> len(e[0])
3
>>> for outer in range(4):
... 	for inner in range(3):
... 		e[outer][inner] = (outer,inner)
... 
>>> e
[[(0, 0), (0, 1), (0, 2)], [(1, 0), (1, 1), (1, 2)], [(2, 0), (2, 1), (2, 2)], [(3, 0), (3, 1), (3, 2)]]
>>>

- Paddy.