From - dyad {

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# From - dyad { (selecting items)

The dyad `{` (from) is used to select items from an array. This is sometimes called indexing an array.

       a =. 5 7 9 4 8
       3 { a	NB. select item at index 3
    4

       0 { a     	NB. indexes start at 0
    5

       2 4 { a 	NB. select 2 items
    9 8

       2 0 4 { a	NB. select 3 items
    9 5 8

From selects items from its argument, and therefore selects rows from tables.

       m =. i. 3 4
       m
    0 1  2  3
    4 5  6  7
    8 9 10 11

       0 { m
    0 1 2 3

       2 1 { m
    8 9 10 11
    4 5  6  7

From selects tables from rank 3 arrays.

       1 { i. 2 3 4
    12 13 14 15
    16 17 18 19
    20 21 22 23

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