unglue

Description

The functions unglue_data(), unglue(), unglue_vec() and unglue_unnest() extract matched substrings using a syntax inspired from glue::glue(). Simple cases don't require regex knowledge at all.

Usage

unglue(x, patterns, open = "{", close = "}", convert = FALSE, multiple = NULL)

unglue_data(
  x,
  patterns,
  open = "{",
  close = "}",
  convert = FALSE,
  multiple = NULL,
  na = NA_character_
)

unglue_vec(
  x,
  patterns,
  var = 1,
  open = "{",
  close = "}",
  convert = FALSE,
  multiple = NULL,
  na = NA_character_
)

unglue_unnest(
  data,
  col,
  patterns,
  open = "{",
  close = "}",
  remove = TRUE,
  convert = FALSE,
  multiple = NULL,
  na = NA_character_
)

Arguments

Details

Depending on the task you might want:

• unglue_data() to return a data frame from a character vector, just as glue::glue_data() does in reverse

• unglue() to return a list of data frames containing the matches

• unglue_vec() to extract one value by element of x, chosen by index or by name.

• unglue_unnest() to extract value from a column of a data frame to new columns

To build the relevant regex pattern special characters will be escaped in the input pattern and the subpatterns will be replaced with ⁠(.*?)⁠ if in standard "{foo}" form. An alternate regular expression can be provided after = so that "{foo=\\d}" will be translated into "(\\d)".

Sometimes we might want to use regex to match a part of the text that won't be extracted, in these cases we just need to omit the name as in "{=\\d}".

unglue_unnest()'s name is a tribute to tidyr::unnest() because unglue_unnest(data, col, patterns) returns a similar output as dplyr::mutate(data, unglued = unglue(col, patterns)) %>% tidyr::unnest() (without requiring any extra package). It is also very close to tidyr::extract() and efforts were made to make the syntax consistent with the latter.

Value

For unglue()a list of one row data frames, for unglue_data a data frame, for unglue_unnest the data frame input with additional columns built from extracted values, for unglue_vec an atomic vector.

Examples

# using an awample from ?glue::glue
if(require(magrittr) && require(glue)) {
  glued_data <- mtcars %>% glue_data("{rownames(.)} has {hp} hp")
  unglue_data(glued_data, "{rownames(.)} has {hp} hp")
}

facts <- c("Antarctica is the largest desert in the world!",
"The largest country in Europe is Russia!",
"The smallest country in Europe is Vatican!",
"Disneyland is the most visited place in Europe! Disneyland is in Paris!",
"The largest island in the world is Green Land!")
facts_df <- data.frame(id = 1:5, facts)

patterns <- c("The {adjective} {place_type} in {bigger_place} is {place}!",
            "{place} is the {adjective} {place_type=[^ ]+} in {bigger_place}!{=.*}")
unglue_data(facts, patterns)

sentences <- c("666 is [a number]", "foo is [a word]",
              "42 is [the answer]", "Area 51 is [unmatched]")
patterns <- c("{number=\\d+} is [{what}]", "{word=\\D+} is [{what}]")
unglue_data(sentences, patterns)

unglue_unnest(facts_df, facts, patterns)
unglue_unnest(facts_df, facts, patterns, remove = FALSE)

Detect if strings are matched by a set of unglue patterns

Description

Returns a logical indicating whether input strings were matched by one or more patterns

Usage

unglue_detect(
  x,
  patterns,
  open = "{",
  close = "}",
  convert = FALSE,
  multiple = NULL
)

Arguments

Value

a vector of logical.

Examples

sentences <- c("666 is [a number]", "foo is [a word]",
               "42 is [the answer]", "Area 51 is [unmatched]")
patterns <- c("{number=\\d+} is [{what}]", "{word=\\D+} is [{what}]")
unglue_detect(sentences, patterns)

Converts unglue pattern to regular regex pattern

Description

Transforms a vector of patterns given in the unglue format to a vector of proper regex (PCRE) patterns (so they can for instance be used with functions from other packages).

Usage

unglue_regex(
  patterns,
  open = "{",
  close = "}",
  use_multiple = FALSE,
  named_capture = FALSE,
  attributes = FALSE
)

Arguments

Value

a character vector.

Examples

patterns <- c("{number=\\d+} is [{what}]", "{word=\\D+} is [{what}]")
unglue_regex(patterns)

unglue_sub

Description

substitute substrings using strings or replacement functions

Usage

unglue_sub(x, patterns, repl, open = "{", close = "}")

Arguments

Examples

unglue_sub(
  c("a and b", "foo or bar"),
  c("{x} and {y}", "{x} or {z}"),
  "XXX")

unglue_sub(
  c("a and b", "foo or bar"),
  c("{x} and {y}", "{x} or {z}"),
  toupper)

unglue_sub(
  c("a and b", "foo or BAR"),
  c("{x} and {y}", "{x} or {z}"),
  list(x= "XXX", y = toupper, z = tolower))