transform variables

# data.table做法：
library(data.table)
DT[ , lapply(.SD, function(x)iconv(x,"UTF8", "BIG5"))]

# 如果有numeric或是integer column的話：
DT[ , lapply(.SD, function(x){
  if (is.character(x))
    iconv(x,"UTF8", "BIG5")
} else return(x)})]


# dplyr做法：
library(dplyr)
DF %>% mutate_each(funs(iconv(., "UTF8", "BIG5")))

# 如果有numeric或是integer column的話：
DF %>% mutate_if(is.character, funs(iconv(., "UTF8", "BIG5")))

# base函數解法：
evalExpr <- lapply(names(DF), function(x){
  bquote(iconv(.(as.symbol(x)), "UTF8",  "BIG5"))
})
do.call(function(...) transform(DF, ...), evalExpr)

# 如果有numeric或是integer column的話：
evalExpr <- lapply(names(DF)[sapply(DF, is.character)],
                   function(x) bquote(iconv(.(as.symbol(x)), "UTF8",  "BIG5")))
do.call(function(...) transform(DF, ...), evalExpr)