numpy array append is not working

Question

i am trying to append in numpy array.it does not showing any error but not appending the values in the array. i can't understand what's the reason.

ind=[]
ind=np.array(ind)
ind

out:array([], dtype=float64)
rand_num
out:0.2581020651429914

for i in T_Yk:
    print i,rand_num,i>=rand_num
    if i>=rand_num:
        np.append(ind,i)


0.841407208505 0.258102065143 True
0.544017164891 0.258102065143 True
0.847014100035 0.258102065143 True
0.837888398913 0.258102065143 True
0.602345432651 0.258102065143 True
0.758088894007 0.258102065143 True
0.875552313712 0.258102065143 True
0.566129640396 0.258102065143 True
0.398095901072 0.258102065143 True
0.708554596955 0.258102065143 True
0.308165627166 0.258102065143 True
0.716732072072 0.258102065143 True
0.760848001298 0.258102065143 True
0.307696603977 0.258102065143 True
0.574524448748 0.258102065143 True
0.608537650411 0.258102065143 True
0.661614576393 0.258102065143 True
0.358783413082 0.258102065143 True
0.396823316883 0.258102065143 True
0.867563492221 0.258102065143 True
0.520237352281 0.258102065143 True
0.866000916749 0.258102065143 True
0.851035162881 0.258102065143 True
0.566755675099 0.258102065143 True
0.687814928058 0.258102065143 True
0.787882814547 0.258102065143 True
0.8790451058 0.258102065143 True
0.538294379248 0.258102065143 True
0.543694673875 0.258102065143 True

but when i print the array ind,it shows

array([], dtype=float64)

Answer 1

np.append, unlike list.append, is not an in-place operation.

Therefore, assign back to original pointer:

ind = np.append(ind, i)