getting the last 2 rows of each group

Community Support
1

how do i go about getting the last two rows in a group?

q)show t:flip ab!(1 1 2 3 3 3;til 6);

a b

1 0

1 1

2 2

3 3

3 4

3 5

q)select[-2] by a from t

a| b

-| -

2| 2

3| 5

q)select b by a from t

a| b    

-| -----

1| 0 1  

2| ,2   

3| 3 4 5

the result i’d like is:

a b

1 0

1 1

2 2

3 4

3 5

thanks,

jack

2

You may find idxs first:

t raze value  exec 2 sublist i by a from t

WBR, Andrey Kozyrev.

???, 31 ??? 2015 ?., 11:49:43 UTC+3 ??? effbiae ???:

how do i go about getting the last two rows in a group?

q)show t:flip ab!(1 1 2 3 3 3;til 6);

a b

1 0

1 1

2 2

3 3

3 4

3 5

q)select[-2] by a from t

a| b

-| -

2| 2

3| 5

q)select b by a from t

a| b    

-| -----

1| 0 1  

2| ,2   

3| 3 4 5

the result i’d like is:

a b

1 0

1 1

2 2

3 4

3 5

thanks,

jack