shaped-slice-view ( array selectors -- view )
NumPy-style shaped-array operations

Prev:	reshape ( array shape -- result )
Next:	shaped-permute ( array axes -- view )

Vocabulary
arrays.shaped

Inputs

array	a shaped-array, a sequence, or a number
selectors	a sequence

Outputs

view	a shaped-array

Word description
Returns a writable view using one integer, shaped-slice, or f selector per selected axis. Integers remove an axis; f and omitted trailing selectors retain the whole axis. Negative indices and slice steps are supported. Writes through the view affect the source storage and vice versa. Nested ordinary sequences are first converted to owned flat storage. Advanced indexing, ellipsis, and new-axis selectors are not implemented.

Examples

USING: arrays arrays.shaped prettyprint ; { 0 1 2 3 4 } f f -1 <shaped-slice> 1array shaped-slice-view shaped-array>array .
{ 4 3 2 1 0 }

Definition

USING: accessors arrays arrays.shaped.private kernel math
sequences ;

IN: arrays.shaped

:: shaped-slice-view ( array selectors -- view )
    array >shaped-array :> shaped shaped shape>> :> dimensions
    selectors length dimensions length >
    [ selectors invalid-shaped-slice ] when
    selectors dimensions length f pad-tail
    :> selection dimensions row-major-strides :> strides
    V{ } clone :> result-shape
    V{ } clone :> result-strides 0 :> offset! selection [|
    selector axis |
        axis dimensions nth :> size axis strides nth
        :> stride selector integer? [
            selector size normalize-axis stride * offset +
            offset!
        ] [
            selector [ ] [ f f 1 <shaped-slice> ] if*
            :> range range shaped-slice?
            [ selector invalid-shaped-slice ] unless
            range size slice-parameters :> ( start count step )
            offset start stride * +
            offset! count result-shape push stride step *
            result-strides push
        ] if
    ] each-index
    shaped underlying>> result-shape >array result-strides
    >array offset <shaped-view> ;