Grabbing nonzero indices

[ahwillia]

Is the preferred way to access the coordinates/indices to use something like

i, j, k = arr.coords  # for a 3d array

Is there a reason why coo arrays don't implement nonzero as a method? I think this would make np.argwhere(arr) work as well without converting to a dense array.

Huge thanks for developing this package -- it will be very useful to me.

[hameerabbasi]

Thanks for the tip! There is a sparse.where method equivalent to np.where that you can use.

[hameerabbasi]

As you know, the ndarray API is relatively large, and it's hard for a project with not many developers to implement it all. In any case, I've implemented your suggestion in #148 (it was relatively simple), and added a test both for the nonzero method and for np.argwhere. I encourage you to take a look if you find the time.

[ahwillia]

Awesome, thanks so much for implementing this so quickly! I'd be happy to help in the future if there are more improvements along these lines.