在python numpy中指定2d数组的大小

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?

Answer 1

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