# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#' Renames columns of a data frame.
#'
#' @param x a data frame.
#' @param map a named character vector, mapping old column names to new ones
#' such that the new ones are in 'names' and the values are the old
#' ones. For example, \code{c(geo='GMA', date='Week Ending')}. If 'map'
#' has length 0, the original data frame is returned.
#'
#' @return The data frame, with the column names renamed.
RenameColumns <- function(x, map=character(0)) {
SetMessageContextString("RenameColumns")
on.exit(SetMessageContextString())
assert_that(is.data.frame(x))
assert_that(is.character(map) || is.null(map))
if (length(map) == 0) {
return(x)
}
assert_that(length(map) > 0,
length(names(map)) == length(map),
is.vector.of.nonempty.strings(names(map)),
msg="'map' must be a named character vector")
x.names <- names(x)
there <- structure(map %in% x.names, names=map)
assert_that(all(there),
msg=Message(FormatText(!there,
"The following specified columns are not ",
"in the data frame: $X")))
i.names <- which(x.names %in% map)
inv.map <- structure(names(map), names=map)
x.names[i.names] <- inv.map[x.names[i.names]]
dups <- structure(duplicated(x.names), names=x.names)
assert_that(!any(dups),
msg=Message(FormatText(dups,
"Duplicated column names: $X")))
names(x) <- x.names
return(x)
}
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