multieval mutate

library(data.table)
library(dplyr)
library(magrittr)
N = 10
T = 5
nItem = 4
m = matrix(rbinom(N*T*nItem, 15, 0.4), N)
dat = data.table(id = 1:nrow(m), m) %>%
  setnames(paste0("V",1:20), paste0(rep(LETTERS[1:nItem],,, T),
    rep(1:T, nItem)))

varChecking = names(dat)[grepl("[A-Z]1", names(dat))]
f = function(x) ifelse(x < 5, 0, x)
dat_out = mutate_each_(dat, funs(f), varChecking)

namesWorking = gsub("([A-Z])1", "\\1", varChecking)
varsWorking = paste0(rep(namesWorking,,,T-1), rep(2:T,nItem))

## method 1
cmd = paste0('ifelse(', rep(namesWorking,,,T-1), '1<5,0,',
    varsWorking, ')')
mutate_(dat_out, .dots= setNames(lapply(cmd, lazyeval:::interp), varsWorking))

## method 2
eval(parse(text = paste0('dat_out=mutate(dat_out,',
  paste0(varsWorking, '=ifelse(', rep(namesWorking,,,T-1), '1<5,0,',
    varsWorking, ')', collapse = ","), ')')))
## 然後就回到原本的左移問題~~~