I have an array A with shape (3,3,3). I want to print A[0], A[1], A[2] only when at least one of the elements of A[0], A[1], A[2] is <=10 or>=30. But I am getting an error. The expected output is attached.

import numpy as np

A=np.array([[[41,42,43],[44,45,46],[47,48,49]],[[11,12,13],[14,15,16],[17,18,19]],
            [[31,32,33],[34,35,36],[37,38,39]]])

for t in range(0,len(A)):
    if(A[t]<=10 or A[t]>=30):
        print(A[t])
    else:
        print("STOP")

The error is

in <module>
    if(A[t]<=10 or A[t]>=30):

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

The expected output is

array([[41, 42, 43],
       [44, 45, 46],
       [47, 48, 49]]) #since no single element of A[0] satisfy <=10 or>=30.

STOP #since A[1] satisfies <=10 or>=30.

CodePudding user response：

Use all() as you want to satisfy each value with the condition.

import numpy as np

A = np.array([[[41, 42, 43],
               [44, 45, 46],
               [47, 48, 49]],
              [[11, 12, 13],
               [14, 15, 16],
               [17, 18, 19]],
              [[31, 32, 33],
               [34, 35, 36],
               [37, 38, 39]]])

for i in range(len(A)):
    if (A[i] <= 10).all() or (A[i] >= 30).all():
        print(A[i])
    else:
        print("STOP")

Output

[[41 42 43]
 [44 45 46]
 [47 48 49]]
STOP
[[31 32 33]
 [34 35 36]
 [37 38 39]]

CodePudding user response：

The iterator will be returning an entire 'row' (or whatever that is in three dimensions), not a single element. If you put:

print(A[t])

in before the test, you'll see what you're checking against:

[[41 42 43]
 [44 45 46]
 [47 48 49]]

so you'll need to 'dig in' to the array a little more by having nested loops.