data.table: using setkey with a column name variable
I have a variable name saved into the string variable which_id.
W is a data.table. How do I call setkey on W with which_id ?
This is what I've tried
> eval( paste( 'setkey(W,' , which_id , ')' ) )  "setkey(W, customer_id_A )"
But a call to tables() shows that the customer_id_A key didn't take.
> evalq( paste( 'setkey(W,' , which_id , ')' ) )  "setkey(W, customer_id_A )"
customer_id_A key still didn't take.
> setkeyv( W , cols=which_id )
> setkeyv( W , cols=c( which_id ) )
--> same thing, customer_id_A key isn't there.
Any pointers? Thanks.
setkeyv should work. Here is a reproducible example:
> library(data.table) data.table 1.8.8 For help type: help("data.table") > W <- data.table(customer_id_A = 1:2) > which_id <- "customer_id_A" > setkeyv(W, which_id) > tables() NAME NROW MB COLS KEY [1,] W 2 1 customer_id_A customer_id_A Total: 1MB