I have task for which I couldn't find a solution.
Suppose we have some indexes which relate to some data.
Now I have vector which describe which indexes to keep and which to remove.
For example: pat =: 4 _3 2 _1
Positive value - tell how many indexes to keep, negative to remove. So the
pat is telling that I need to keep 4 first indexes then remove 3 next,
keep another 2, remove 1, keep 4, remove 3 and so on.
I need function that for giving index give me new index after applying
such pattern. Indexes of removed items - is index of next keeped item.
So applying this function to i.20 and pat I should see:
OLD: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
NEW: 0 1 2 3 4 4 4 4 5 6 6 7 8 9 10 10 10 10 11 12
Another function will make inverse calculation - for each value from NEW
give the biggest value from OLD.
I wonder is it posible to achieve whithout precalculating vector of NEW
indexes, just by calculating new value from given pat and old index?
Thanks in advance,
Mikl
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Mikl
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