Used to select columns in a data.table according to the column names.

selectR.R

contains <- function(pattern) {
  pattern <- pattern
  call_info <- deparse(sys.calls()[[1]])
  if (grepl("(^.+\\()(.+)(\\)$)",call_info)) {
    this_name <- sub("(^.+\\()(.+)(\\)$)","\\2",call_info)
  } else {
    this_name <- strsplit(call_info,"\\[")[[1]][1]
  }
  this <- get(this_name)
  this_names <- names(this)
  eval.parent(grep(pattern, this_names))
}

startswith <- function(pattern) {
  contains(paste0("^", pattern))
}

endswith <- function(pattern) {
  contains(paste0(pattern, "$"))
}