selectColumns: Select Columns from a Data Frame
In KWB-R/kwb.utils: General Utility Functions Developed at KWB

selectColumns

R Documentation

Select Columns from a Data Frame

Description

Select columns from a data frame. Stop with message if columns do not exist

Usage

selectColumns(
  x,
  columns = NULL,
  pattern = NULL,
  drop = (length(columns) == 1),
  do.stop = TRUE
)

Arguments

`x`	data frame
`columns`	vector of column names. If `columns` is of length 0 or `NULL` (default) or `NA` `x` is returned unchanged.
`pattern`	regular expression matching the names of the columns to be selected. Will only be evaluated if no explicit column names are given in `columns`.
`drop`	if `TRUE` and if only one column is to be selected the result is a vector (one dimensional) containing the values of the selected column and not a data frame. One dimension has been dropped then. See the `help("[.data.frame")`. The default is `TRUE` if `length(columns) == 1`, else `FALSE`.
`do.stop`	this flag controls whether the function stops (`do.stop = TRUE`) or not (`do.stop = FALSE`) if there are non-existing columns to be selected. If `do.stop = FALSE` only those columns are selected that actually exist

Value

data frame containing the columns of x that are specified in columns or x itself if columns is NULL or a vector containing the values of column value if columns is of length 1 and drop = TRUE (which is the default in this case).