specifying size of a 2d array in python numpy

Question

I would like to statically initialize the size of an N by N 2d array in python's numpy where N is a variable (from a SQL query). The equivalent Java would be:

N = code from sql query
int[][] mat = new int[N][N]

How would I do this in numpy? Or what about a Matrix type?

JoshAdel · Accepted Answer · 2013-06-24 02:31:25Z

2

You can do it in a number of ways, but to create an empty array that you will later fill, you might consider:

N = 100
mat = np.empty((N,N))

There are a large number of other methods detailed in the docs:

http://docs.scipy.org/doc/numpy/reference/routines.array-creation.html

answered Jun 24, 2013 at 2:31

JoshAdel

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2 Comments

CodeKingPlusPlus Over a year ago

What is a convenient way to look into the docs? From the interpreter I typed help(numpy) and it kept on spitting out documentation... I eventually had to give the terminate signal...

JoshAdel Over a year ago

I would recommend using the IPython interpreter that allows you to do something like np.empty? which will give you that method's specific docs (ipython.org/ipython-doc/dev/interactive/…)

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