[WORK] groupBy is in! Next: aggregate

[Russel Winder via Digitalmars-d]

On Fri, 2015-01-23 at 10:08 -0800, Andrei Alexandrescu via Digitalmars-d
wrote:
[…]
> #!/usr/bin/rdmd
> 
> void main()
> {
>      import std.algorithm, std.stdio;
>      [293, 453, 600, 929, 339, 812, 222, 680, 529, 768]
>          .groupBy!(a => a & 1)
>          .writeln;
> }
> ----
> 
> [[293, 453], [600], [929, 339], [812, 222, 680], [529], [768]]
> 
[…]

I think I must be missing something, for me the result of a groupBy
operation on the above input data should be:

[1:[293, 453, 929, 339, 529], 0:[600, 812, 222, 680, 768]]

i.e. a map with keys being the cases and values being the values that
meet the case. In this example a & 1 asks for cases "lowest bit 0 or 1"
aka "odd or even".

There is nothing wrong with the semantics of the result above, but is
it's name "group by" as understood by the rest of the world?


-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
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