How can I make a 3-dimensional array in python

Question

I have been writing a simple version of Conway's Life simulation in python.

First I initialized a two dimensional array using the below code (which I probably learned on this site)

def makearray():
    for i in range(n):
        a.append(['x'] * m)

...and I access the cells in that array by storing, or checking the value of, a[2][5] or what have you.

That has worked nicely. But now I realize I need to make a second array, identical to the first, which will store the results of the evaluation that I do on the first array.

I know that I could just make a second array by repeating the exact same code but instead call the second array b instead of a. BUT, it would be a cooler, cleaner way process things if I simply made this into a 3-dimensional array, and the new dimension that I introduce would only be two units "wide" ... it would just have 0 and 1.

So, echoing the above, I'd like the end result to have my array so that I could check the value of a[1][2][5] ... or a[0][2][5].

But, can you give me tips on how I would do the initialization of that array? similar to the initializing loop I pasted above... but with the extra level? :)

Giant thanks!

Have you considered using numpy? First I was reluctant to use another library as a beginner, but it is really comfortable to manipulate arrays with numpy. I am happy that I put the effort into it. — Mr. T
– Mr. T, Commented Jan 13, 2018 at 12:56
in the future, and for any big project, I would probably do just that. but for this thing, I'm trying to pride myself on making a lean little program, so I'd rather keep dependencies out of it... but I appreciate that comment... I do recall that one can do arrays in a more normal feeling way using libraries — estephan500
– estephan500, Commented Jan 13, 2018 at 13:43

Mixone · Accepted Answer · 2018-01-13 12:57:43Z

1

Array containing two matrices of size n

def makematrix(n):
    return [['x'] * n for i in range(n)]

threeD = [makematrix(5), makematrix(5)]

Array containing m matrices of size n

def makematrix(n):
    return [['x'] * n for i in range(n)]

def makearray(m, n):
    return [makematrix(n) for i in range(m)]

threeD = makearray(4, 5)

Array containing two arrays of increasing size

def makearray(n):
    return [['x'] * i for i in range(n)]

threeD = [makearray(5), makearray(5)]

edited Jan 13, 2018 at 12:57

answered Jan 13, 2018 at 12:44

Mixone

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3 Comments

Mr. T Over a year ago

Have you actually looked at the output of your function?

Mixone Over a year ago

yeah its what is being asked, he didnt ask for a matrix just arrays

estephan500 Over a year ago

after a little playing, your second one seems to be doing the trick. thanks. I wish I could look at a list comprehension ... in this kind of tangled context... and see it come to life in my head.

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How can I make a 3-dimensional array in python

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Array containing two matrices of size n

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Array containing two arrays of increasing size

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