How Pytorch Tensor get the index of specific value

Question

In python list, we can use list.index(somevalue). How can pytorch do this?
For example:

    a=[1,2,3]
    print(a.index(2))

Answer 1

Can be done by converting to numpy as follows

import torch
x = torch.range(1,4)
print(x)
===> tensor([ 1.,  2.,  3.,  4.]) 
nx = x.numpy()
np.where(nx == 3)[0][0]
===> 2

Answer 2

I think there is no direct translation from list.index() to a pytorch function. However, you can achieve similar results using tensor==number and then the nonzero() function. For example:

t = torch.Tensor([1, 2, 3])
print ((t == 2).nonzero())

This piece of code returns

1

[torch.LongTensor of size 1x1]

Answer 3

For floating point tensors, I use this to get the index of the element in the tensor.

print((torch.abs((torch.max(your_tensor).item()-your_tensor))<0.0001).nonzero())

Here I want to get the index of max_value in the float tensor, you can also put your value like this to get the index of any elements in tensor.

print((torch.abs((YOUR_VALUE-your_tensor))<0.0001).nonzero())

Answer 4

for finding index of an element in 1d tensor/array Example

mat=torch.tensor([1,8,5,3])

to find index of 5

five=5

numb_of_col=4
for o in range(numb_of_col):
   if mat[o]==five:
     print(torch.tensor([o]))

To find element index of a 2d/3d tensor covert it into 1d #ie example.view(number of elements)

Example

mat=torch.tensor([[1,2],[4,3])
#to find index of 2

five = 2
mat=mat.view(4)
numb_of_col = 4
for o in range(numb_of_col):
   if mat[o] == five:
     print(torch.tensor([o]))    

Answer 5

    import torch
    x_data = variable(torch.Tensor([[1.0], [2.0], [3.0]]))
    print(x_data.data[0])
    >>tensor([1.])