I have problem with matrices in python

I have problems, I can not assign the complete data to the vector, it must be complete in the matrix and I could not, since I try to change the data type of the matrix, it does not give me.

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import random
import numpy as np
import  math as mt 

m=10
n=3

datos = np.zeros((m,n), dtype= str )

for i in range(m):

    X1= random.random()*63
    datos[i,0] =X1

for i in range(m):

    XB=(int(datos[i,0]))
    XBD=(int((mt.modf(X1)[0]*100)))

    XB1=bin(XB)[2:]
    XB2=bin(XBD)[2:]

    XB1=( "{:06d}".format (int(XB1)))
    XB2=( "{:07d}".format (int(XB2)))

    BX= XB1 + XB2

    datos[i,1] = BX

print(datos)