python - Combine list of numpy arrays and reshape -

i'm hoping me following. have 2 lists of arrays, should linked each-other. each list stands object. arr1 , arr2 attributes of object. example:

import numpy np  arr1 = [np.array([1, 2, 3]), np.array([1, 2]), np.array([2, 3])] arr2 = [np.array([20, 50, 30]), np.array([50, 50]), np.array([75, 25])] 

the arrays linked each other in 1 in arr1, first array belongs 20 in arr2 first array. result i'm looking in example numpy array size 3,4. 'columns' stand 0, 1, 2, 3 (the numbers in arr1, plus 0) , rows filled corresponding values of arr2. when there no corresponding values cell should 0. example:

array([[ 0, 20, 50, 30],        [ 0, 50, 50,  0],        [ 0,  0, 75, 25]]) 

how link these 2 list of arrays , reshape them in desired format shown in above example?

many thanks!

here's almost* vectorized approach -

lens = np.array([len(i) in arr1])  n = len(arr1) row_idx = np.repeat(np.arange(n),lens) col_idx = np.concatenate(arr1)  m = col_idx.max()+1 out = np.zeros((n,m),dtype=int) out[row_idx,col_idx] = np.concatenate(arr2) 

*: because of loop comprehension @ start, should computationally negligible doesn't involve computation there.