How to return the index of an element in a 2d array in python?

Question

Assuming I want to use the position of an element in a 2d list knowing the element itself, what would be the command to find the index? For a simple list the method list.index(element) works, for example:

    my_list = ["banana", "yam", "mango", "apple"]
    print(my_list.index("yam")
    >> 1
    print(my_list[my_list.index("yam")])
    >> yam

But the same method doesn't work for 2d arrays. For example:

    array = [["banana", "yam"],["mango", "apple"]]
    print(array.index("yam"))

I get a ValueError: 'yam' is not in list.

Does this answer your question? How to find the index of a value in 2d array in Python? — Mady Daby
– Mady Daby, Commented Apr 22, 2021 at 8:52
That is not a "2D array". That is just a list with other list objects in it. In any case, what value to do expect? — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Apr 22, 2021 at 8:58

Sîd Âlï · Accepted Answer · 2021-04-22 16:08:49Z

3

u may use this answer

c="yam"
index=[(i, fruits.index(c)) for i, fruits in enumerate(array) if c in fruits]

answered Apr 22, 2021 at 16:08

Sîd Âlï

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Sîd Âlï · Accepted Answer · 2021-04-22 09:13:34Z

1

this is my code

array = [["banana", "yam"],["mango", "apple"]]
for i,j  in enumerate(array):
     if "yam" in j:
         index=(i,j.index("yam"))
         break
print(index)

answered Apr 22, 2021 at 9:13

Sîd Âlï

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1 Comment

Supernyv Over a year ago

Thanks. So there really is no simpler way. I intend to use the found index just like I would for a simple list (for example to replace the element in that index by another one). I guess this is okay , thanks!

Serge de Gosson de Varennes · Accepted Answer · 2021-04-22 10:40:59Z

0

What you can do is use np.where in the following way:

a = np.array([["banana", "yam"],["mango", "apple"]])
list(zip(*np.where(a == "yam")))
>> [(0, 1)]

edited Apr 22, 2021 at 10:40

Serge de Gosson de Varennes

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answered Apr 22, 2021 at 9:03

Octav

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2 Comments

Supernyv Over a year ago

Is there another way without using numpy?

Octav Over a year ago

I don't know. Only if you do a manual search... for in for

Supernyv · Accepted Answer · 2021-04-23 15:01:21Z

0

This worked fine. I wrote a function to return the index for any given element in the array!

enter image description here

edited Apr 23, 2021 at 15:01

answered Apr 23, 2021 at 2:24

Supernyv

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