r - Integers/expressions as names for elements in lists -

i trying understand names, lists , lists of lists in r. convenient have way dynamically label them this:

> ll <- list("1" = 2) > ll $`1` [1] 2 

but not working:

> ll <- list(as.character(1) = 2) error: unexpected '=' in "ll <- list(as.character(1) =" 

neither this:

> ll <- list(paste(1) = 2) error: unexpected '=' in "ll <- list(paste(1) =" 

why that? both paste() , as.character() returning "1".

the reason paste(1) function call evaluates string, not string itself.

the the r language definition says this:

each argument can tagged (tag=expr), or simple expression.  can empty or can 1 of special tokens ‘...’, ‘..2’, etc.  tag can identifier or text string. 

thus, tags can't expressions.

however, if want set names (which attribute), can structure, eg

> structure(1:5, names=letters[1:5]) b c d e  1 2 3 4 5  

here, letters[1:5] expression.