[FIXED] numpy 2D array of tuples

Issue

I want to create a 2D numpy array from the cartesian product of two lists.

from itertools import product
b1 = 25
b2 = 40
step = 2
lt1 = range(1,b1+1,step)
lt2 = range(1,b2+1,step)
func(product(lt1,lt2,repeat=1))

I want the function to create a 2D numpy array such that the entries are the tuple pairs.

For example, if lt1 = [2,3] and lt2 = [1,4,7], then the 2D array should be

[ [(2,1), (2,4), (2,7)],
  [(3,1), (3,4), (3,7)] ]

My ultimate aim is to create blocks of fixed size from the array and retrieve values corresponding to the block tuples (from a dictionary of lists with keys as the tuples) and eliminate some blocks.

Any help ?

Solution

I hope I've understood your question right. To create 2D numpy array of tuples of integers you can do:

from itertools import product

lt1 = [2, 3]
lt2 = [1, 4, 7]

arr = np.array([*product(lt1, lt2)], dtype=("i,i")).reshape(len(lt1), len(lt2))
print(arr)

Prints:

[[(2, 1) (2, 4) (2, 7)]
 [(3, 1) (3, 4) (3, 7)]]

Answered By - Andrej Kesely