r - plyr functions and standard evaluation -

i wrap plyr functions in own functions. want pass function object , variable (unquoted) on apply cut function.

x <- data.frame(time = seq(sys.date() - 99, sys.date(), 1))  dlply(x, .(week = cut(time, "1 week")), "[")  f <- function(datas, var) {   var <- deparse(substitute(var))    dlply(x, .(week = cut(var, "1 week")), "[") }  f(x, time) # fail 

i don't know how use object var specify variable value , not "var" variable, within ddply.

unlike in dplyr there no standard evaluation versions of plyr functions ? read can use strings, example dlply(x, .(week = cut("time", "1 week")), "[") fails

i tried lazyeval, i'm lost in standard/non standard evaluation universe.

you seem have unnecessary deparse in code , don't evaluate var in right place. works following.

f <- function(datas, var) {   var <- substitute(var)   dlply(datas, .(week = cut(eval(var), "1 week")), "[") }