Add fancy indexing

[ALMerrill]

Hey, I'm just curious if there are any plans to implement "fancy indexing", where you can pass a list of indeces to an MfArray, and return the items at those indeces, like in numpy. Thanks, its a great library so far.

[jjjkkkjjj]

@ALMerrill
I'd like to implement "fancy indexing", of course.
OK, I'll try to do it on this weekend, but don't expect me excessively! 😅

[ALMerrill]

That would be awesome! Whenever you can would be great

[ALMerrill]

Also, out of curiosity, is there a way to improve performance with the Boolean indexing? With how I’m using it, it looks like things like array > someNumber is taking the majority of the time. I was just curious if you knew of any way to improve performance on calls like that. Thanks so much!

[jjjkkkjjj]

it looks like things like array > someNumber is taking the majority of the time.

Yes, your point is correct. The code to improve performance may be here firstly. I think there are much redundant process in this code. So, i should simplify this code.

[jjjkkkjjj]

Or use boolean as storedType as you pointed out, but this will change many codes...

[jjjkkkjjj]

Official code is here; https://github.com/numpy/numpy/blob/cf1306a842d7b1064270bd06951a485121e60816/numpy/core/src/multiarray/mapping.c#L1608

[jjjkkkjjj]

@ALMerrill
I implemented fancy indexing getter!
You can try it by fetching develop branch.
You can pass Int MfArray instead of list to MfArray like this;

let a = MfArray([[1, 2], [3, 4], [5, 6]])
a[MfArray([0, 1, 2]), MfArray([0, 1, 0])]
/*
mfarray = 
[	1,		4,		5], type=Int, shape=[3]
*/

numpy;

>>> x = np.array([[1, 2], [3, 4], [5, 6]])
>>> x[[0, 1, 2], [0, 1, 0]]
array([1, 4, 5])

I don't know if I can implement setter...

[ALMerrill]

awesome, thank you for the update!

[jjjkkkjjj]

@ALMerrill
I've just implemented fancy setter!!
I didn't check performance, but anyway you can use fancy indexing for MfArray🎉

Setter;

let a = MfArray([[1, 2], [3, 4], [5, 6]])
            
a[MfArray([0, 1, 2]), MfArray([0, -1, 0])] = MfArray([999,888,777])
print(a)
/*
mfarray = 
[[	999,		2],
[	3,		888],
[	777,		6]], type=Int, shape=[3, 2]
*/
            
a.T[MfArray([0, 1, -1]), MfArray([0, 1, 0])] = MfArray([-999,-888,-777])
print(a)
/*
mfarray = 
[[	-999,		-777],
[	3,		-888],
[	777,		6]], type=Int, shape=[3, 2]
*/

[ALMerrill]

Nice! That's awesome!