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kdb

Extracting kdb list values based on some condition

Say we have a kdb list

L1:(1 2 3 4 5)

Apply condition

L1 < 3

And how can I retrieve result in another list (1 2)

Solution

  • You can use the where keyword for this:

    q)l1 where l1<3
1 2

    Applying l1<3 will return a list of booleans 11000b. Using where on this list will return the index of every 1b 

    q)where 11000b
0 1

    Then indexing back into the original list will return the result in another list.