Feature request: reverse method

[maasha]

Can we please have a reverse method that efficiently reverses the order of elements inline.

Cheers,

Martin

[masa16]

This is achieved by the bracket method:
a[-1..0]

[maasha]

Yes, I found out. I was still surprised that there wasn't a reverse method. Ruby is about keeping surprises to a minimum, yes?

[masa16]

I can see the natural behaviour of reverse method for one-dimensional array. But I havent found what a.reverse shoud return if a is a multi-dimensinal array.

[dicom]

I like the convenience of a reverse method.

How about:

NArray#reverse(index=0)

On a one-dimensional array:

v = NArray.int(4).indgen!
[ 0, 1, 2, 3 ]
v.reverse
[ 3, 2, 1, 0 ]
v.reverse(0)
[ 3, 2, 1, 0 ]

Two-dimensional array:

arr = NArray.int(2,2).indgen!
[ [ 0, 1 ], 
  [ 2, 3 ] ] 
arr.reverse
[ [ 1, 0 ], 
  [ 3, 2 ] ] 
arr.reverse(0)
[ [ 1, 0 ], 
  [ 3, 2 ] ]
arr.reverse(1)
[ [ 2, 3 ], 
  [ 0, 1 ] ]  

And of course this principle works fine on higher dimensional arrays as well.

[masa16]

arr = NArray.int(2,2).indgen!
[ [ 0, 1 ], 
  [ 2, 3 ] ]

arr.reverse
[ [ 1, 0 ], 
  [ 3, 2 ] ] 

or

arr.reverse
[ [ 3, 2 ], 
  [ 1, 0 ] ] 

?

[dicom]

How about:

NArray#reverse(index=true)

arr = NArray.int(2,2).indgen!
[ [ 0, 1 ], 
  [ 2, 3 ] ]

Without argument, all dimensions are reversed:

arr.reverse
[ [ 3, 2 ], 
  [ 1, 0 ] ]

If an index/dimension is specified, only the specified dimension gets reversed.
Reversing rows:

arr.reverse(0)
[ [ 1, 0 ], 
  [ 3, 2 ] ]

Reversing columns:

arr.reverse(1)
[ [ 2, 3 ], 
  [ 0, 1 ] ]