Implement Python-Style Array Indexing

[nodnarb90]

I think it would save a bit of space, and time, if we could use a negative array index value in order to quickly get the last element of an array.  This would also work for 2nd to last item, 3rd to last, etc.

When I started working with Python I thought it was rather useful and intuitive to be able to quickly reference the last item in an array in that way.  Like so:

>>> a= [1, 2, 3]
>>> print a[-3]
1
>>> print a[-2]
2
>>> print a[-1]
3

[garrettmarsh]

Duplicate:

http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Negative-Values-in-Index-Array-or-Array-Subset/idi-p/9...

...among several others.

[ToeCutter]

Like the idea, but want to keep array indexing quick and light and this would add another branch in the internal code. As an alternative, how about NI adds a separate function 'Index array from end'?

[crossrulz]

Use Reverse 1D Array before indexing if you want to go from the end.

[garrettmarsh]

Also, if this were implemented, you would run into the problem of breaking code which relies on the current behavior (that a negative index returns the default value for that data type).

[GregFreeman]

I agree with garrett...I think this is not feasible for the reason he listed. 

[lvABC]

I use Delete From Array Function to get last element where the default is the index of the last element in the array.
http://zone.ni.com/reference/en-xx/help/371361j-01/glang/delete_from_array/

[nodnarb90]

Getting the array size and decrementing isn't so cumbersome that I think another method should be added specifically for that function, but I do realize it would probably increase the operations it takes for that function to complete.  I would just like to have the ability to index in the way that Python does.

I am aware that an "out-of-bounds" index will return the default value for that array data type, whether that index is too large or too small (negative), however, I don't believe I personally have ever created code that relied upon that.

The idea of a negative index is universal and could also be applied to other functions, such as string subset, to quickly get the extension.  I do realize there are functions to do this, and that it wouldn't be done this way because not all extensions use 3 characters, but this is just a demonstration for demonstrations sake.  See below.

Thanks for all the input!

[altenbach]

I think we should keep all discussions in the original idea thread to avoid duplication of effort. I don't want to repeat everything I alread said.

[JordanG]

Dupe: http://forums.ni.com/t5/LabVIEW-Idea-Exchange/Negative-Values-in-Index-Array-or-Array-Subset/idi-p/9...

[Yogesh_Redemptor]

To my knowledge this may lead to confusion, because '-1' index mean not valid or search not found.

We should leave '-1' for the same and should not use for other purpose like to index last data.

Regards,

Yogesh R