I need to generate an m*n matrix with 1 and 0 where the sum of each row is 1 and each column is greater than or equal to 1. I'm trying this code but I don't know how to limit my condition on the columns, since sometimes I get zero columns and I need them all to have at least one 1. How could I limit the sum in the columns to be at least 1?
pt = []
sumr = 0
sumc = []
for i in range(n):
quantity = random.choices([1])
row = np.zeros(p, dtype=int)
idx = np.random.choice(range(p), quantity, replace=False)
row[idx] = 1
pt.append(row)
for j in range(len(pt[0])):
sumc.append(sum([row[j] for row in pt]))
print(sumc)
I would just create a matrix with ones in random places, and then check if there are still zero columns once we near the end so we don't leave any empty:
import numpy as np
import random
def make_mat(m, n):
if (n > m):
print("Invalid matrix dimensions.")
return
mat = np.zeros((m,n))
zero_cols = [True]*n # keep track of zero columns
for row in range(m):
# if there are N zero cols and N rows remaining, place 1 at randomly selected zero column place
if len(np.where(zero_cols)[0]) == (m - row):
idx = random.choice(np.where(zero_cols)[0])
# otherwise, just select a random index
else:
idx = random.randint(0, n-1)
mat[row][idx] = 1
zero_cols[idx] = False
return mat
print(make_mat(10, 8))
However, this can be simplified if we make use of an identity matrix:
import numpy as np
def make_mat_id(m, n):
if (n > m):
print("Invalid matrix dimensions.")
return
id_mat = np.identity(n)
# add rows with one in random place
mat = np.concatenate((id_mat, [np.where(np.arange(n) == np.random.choice(np.arange(n)), 1, 0) for _ in range(m-n)]))
# make sure we no longer have the identity matrix
np.random.shuffle(mat)
return mat
print(make_mat_id(10, 8)