R: Extract one column into multiple columns.

extract {tidyr}

R Documentation

Extract one column into multiple columns.

Description

Given a regular expression with capturing groups, extract() turns each group into a new column. If the groups don't match, or the input is NA, the output will be NA.

Usage

extract(data, col, into, regex = "([[:alnum:]]+)", remove = TRUE,
  convert = FALSE, ...)

Arguments

`data`	A data frame.
`col`	Column name or position. This is passed to `tidyselect::vars_pull()`. This argument is passed by expression and supports quasiquotation (you can unquote column names or column positions).
`into`	Names of new variables to create as character vector.
`regex`	a regular expression used to extract the desired values. The should be one group (defined by `()`) for each element of `into`.
`remove`	If `TRUE`, remove input column from output data frame.
`convert`	If `TRUE`, will run `type.convert()` with `as.is = TRUE` on new columns. This is useful if the component columns are integer, numeric or logical.
`...`	Other arguments passed on to `regexec()` to control how the regular expression is processed.

Examples

library(dplyr)
df <- data.frame(x = c(NA, "a-b", "a-d", "b-c", "d-e"))
df %>% extract(x, "A")
df %>% extract(x, c("A", "B"), "([[:alnum:]]+)-([[:alnum:]]+)")

# If no match, NA:
df %>% extract(x, c("A", "B"), "([a-d]+)-([a-d]+)")

[Package tidyr version 0.8.1 Index]