I have the below trades table in my q session:
q)meta trades c | t f a -----| ----- time | p sym | s g src | s g price| f size | i q)
Then, why does it need each both for the sv function when x and y are joined already and then passed into sv:
q)update symsrc:{sv'(x,'y)}[sym;src] from 1#trades time sym src price size symsrc -------------------------------------------------------- 2023.06.04D08:00:49.248000000 ORCL L 40.67 3984 ORCL.L q)update symsrc:{-1 .Q.s1 x,y; sv’(x,'y)}[sym;src] from 1#trades ORCLL time sym src price size symsrc -------------------------------------------------------- 2023.06.04D08:00:49.248000000 ORCL L 40.67 3984 ORCL.L
You’ll get a type error without the each, because you need to create a scalar from each vector (i.e. each pair of symbols)
q)t:(sym:ORCLAPPL;src:LR) t sym src -------- ORCL L APPL R q) update symsrc: sv (sym,'src) from t 'type [0] update symsrc: sv (sym,‘src) from t ^ q) update symsrc:` sv’(sym,'src) from t sym src symsrc --------------- ORCL L ORCL.L APPL R APPL.R
Bonus tip - as shown above, you can avoid using a lambda by using parenthesis so the parser doesn’t interpret the comma as a new column statement.
David has already answered the question here, but it’s worth noting that you can do this operation very succinctly using .Q.dd:
q)update symsrc:.Q.dd’[sym;src]from trades time sym src price size symsrc -------------------------------------------------------- 2023.06.04D10:22:20.088377000 ORCL L 40.67 3984 ORCL.L