Split single column to multiple columns in KDB - kdb

Question

I want to split values in a column to multiple columns after applying a complex function.
e.g. For the following trade table t , I want to split the sym into 2 separate columns sym and src. However, the function I would be applying would be slightly complex.
q)t:([] time:10:01:01 10:01:03 10:01:04;sym:`goog.l`vod.l`apple.o;qty:100 200 150)
time sym qty
--------------------
10:01:01 goog.l 100
10:01:03 vod.l 200
10:01:04 apple.o 150

Answer 1

If your table is very big and the sym column is very repetitive (which it looks like it will be if it's tick data) then the following will be much quicker:
f:{` vs'x}
#[t;`col1`col2;:;flip .Q.fu[f]t`sym]

Answer 2

You can create a table of sym and src by splitting on ., creating a dictionary then using flip to create a table:
q)show r:exec flip`sym`src!flip` vs/:sym from t
sym src
---------
goog l
vod l
apple o
This can be joined to the original table using each-both ,':
q)t,'r
time sym qty src
----------------------
10:01:01 goog 100 l
10:01:03 vod 200 l
10:01:04 apple 150 o
If column order is important then this can be fixed with xcols:
q)`time`sym`src xcols t,'r
time sym src qty
----------------------
10:01:01 goog l 100
10:01:03 vod l 200
10:01:04 apple o 150

Answer 3

One of the way to get this done is :
q)update sym:sym[;0] , mkt:sym[;1] from update ` vs/:sym from t
time sym qty mkt
----------------------
10:01:01 goog 100 l
10:01:03 vod 200 l
10:01:04 apple 150 o
If you are not intrested in any other columns except the one from the table that needs spliting then
q)exec {`s`mkt!` vs x}each sym from t
s mkt
---------
goog l
vod l
apple o

Answer 4

Another option would be;
q)(,'/)(t;flip`sym`src!exec flip ` vs'sym from t)
time sym qty src
----------------------
10:01:01 goog 100 l
10:01:03 vod 200 l
10:01:04 apple 150 o