Finding index of array in 2 multidimensional array in Python

Question

I have an array

v = (x,y,z)

and two multidimensional array

l = (a,b,c),(d,e,f)

and

r = (g,h,i),(l,m,n),(x,y,z).

I want to know the index of v no matter if is in the first or second multidimensional array. I tried numpy.where(v==l)[0][0] but it returns:

Index 0 is out of bounds for axis 0 with size 0.

Works only if I know before the matrix where I have to search the Index, but I don't. Thanks

And If I want to know the index and the array that contains it?

Answer 1

Define a function that accepts the item to be searched and the list of array to be searched in and use a loop to find that item in each array. Use exception handling to catch the IndexError.

>>> import numpy as np
>>> v = np.array([[1, 2, 3]])
>>> r = np.array([[1, 2, 3], [0, 9, 8], [2, 4, 4]])
>>> l = np.array([[4, 5, 6], [7, 8, 9]])
def get_index(seq, *arrays):
    for array in arrays:
        try:
            return np.where(array==seq)[0][0]
        except IndexError:
            pass
...         
>>> get_index(v, r, l)
0
>>> get_index(np.array([7, 8, 9]), r, l)
1

You'd get None as output if the item is not found in any of the array.

Update:

If you want the name as well then pass the arrays in a dictionary:

 def get_index(seq, **arrays):
    for name, array in arrays.items():
        try:
            return name, np.where(array==seq)[0][0]
        except IndexError:
            pass
...         
>>> get_index(v, **dict(r=r, l=l))
('r', 0)
>>> get_index(np.array([7, 8, 9]), **dict(r=r, l=l))
('l', 1)

Answer 2

def containsArray(v):
    for index, arr in enumerate(l):
        if v == arr:
            ret index;

    for index, arr in enumerate(r):
        if v == arr:
            ret index;