Multidimensional array in Python

Question

I have a little Java problem I want to translate to Python. Therefor I need a multidimensional array. In Java it looks like:

double dArray[][][] = new double[x.l         


        

Answer 1

Here's a quick way to create a nested 3-dimensional list initialized with zeros:

# dim1, dim2, dim3 are the dimensions of the array
a =[[[0 for _ in range(dim1)] for _ in range(dim2)] for _ in range(dim1) ]
a[0][0][0] = 1

this is a list of lists of lists, a bit more flexible than an array, you can do:

a[0][0] = [1,2,3,4]

to replace a whole row in the array, or even abuse it like that:

a[0] = "Ouch"
print a[0][0] #will print "O", since strings are indexable the same way as lists
print a[0][0][0] #will raise an error, since "O" isn't indexable

but if you need performance, then I agree that numpy is the way to go.

Also, beware of:

a = [[[0] * 5]*5]*5]

If you try a[0][0][0]=7 on the object above, you will see what's wrong with that.