Re: How can I apply a function with ‘if’ to a table?

[amcnaught921]

Hey,

 

The following will give the solution you require

q)t1
TimeStamp stock p1 p2
----------------------
2018.01.01 AAPL 1 -1
2018.01.01 AAPL 2 1
2018.01.02 GOOGL -2 2
2018.01.02 GOOGL 3 0

q)f:{$[0=x+y;0;x*y]}

q)t1:update r:f'[p1;p2] from t1

TimeStamp stock p1 p2 r
------------------------
2018.01.01 AAPL 1 -1 0
2018.01.01 AAPL 2 1 2
2018.01.02 GOOGL -2 2 0
2018.01.02 GOOGL 3 0 0

Some documentation on $ also here: https://code.kx.com/q/ref/cond/