Hi all!
I looked for a version of Cut which takes the number of items in each
group as left argument. I didn't find one. I think it is what you most
often need, because it allows groups with zero length content.
I made CutN as an illustration:
CutN=:((# {. 0 , [: }: [: +/\ ])([: < [ + [: i. ])"0 ])@:[ {&.>/ [: < ]
(i.0) CutN i.0
(,0) CutN i.0
┌┐
││
└┘
(,1) CutN 10+i.1
┌──┐
│10│
└──┘
0 2 CutN 10+i.2
┌┬─────┐
││10 11│
└┴─────┘
2 5 0 CutN 10+i.7
┌─────┬──────────────┬┐
│10 11│12 13 14 15 16││
└─────┴──────────────┴┘
0 7 0 CutN 10+i.7
┌┬────────────────────┬┐
││10 11 12 13 14 15 16││
└┴────────────────────┴┘
Cheers,
Erling Hellenäs
Den 2017-10-20 kl. 10:42, skrev 'Jon Hough' via Programming:
The problem:
Let X be an array.
X=: i. 50 NB. example
Let 'split' be the percentages that each subarray takes from X, sequentially
e.g
split =: 0.35 0.35 0.3 NB. first array takes 35% , second sub array takes 35%,
third takes 30%
So in the end
My solution
splitSubs =: -.~&.>/\@:(i.&.>"0@:<"0)@:}.@:>.@:((+/\ - ])@:[ (* , ]) #@:])
split splitSubs X
This gives 3 boxed arrays. Each array holds the indices to take from X.
There is a slight problem in that the first and second subarrays have
different
length, due to rounding error. I am not too bothered about that since,
depending on the size of X and the percentages, this is
unavoidable.
Any more succinct, nicer solutions?
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