tidyr's extract

Intermediate Regular Expressions in R

Angelo Zehr

Data Journalist

Functions used so far

• str_match
• str_replace
• str_match_all
• str_replace_all
• ...

Where regular expressions and data frames meet:

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

The arguments of extract

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

• data

• col

• into

• regex

• remove

• convert

Movies data frame

What we can do with str_match

screens_per_movie %<>%
  mutate(
    is_3d = str_match(line, "3D")
  )

What the result of str_match looks like

screens_per_movie %<>%
  mutate(
    is_3d = str_match(line, "3D")
  )

str_match can only match one information

This is what extract can do for us

This is what extract can do for us

extract(
  screens_per_movie,
  col = "line",
  into = c("is_3d", "screens"),
  regex = "(3D).*?(\\d+)$",
  remove = FALSE
 )

The result of extract

extract(
  screens_per_movie,
  col = "line",
  into = c("is_3d", "screens"),
  regex = "(3D).*?(\\d+)$",
  remove = FALSE
)

Let's practice!

Intermediate Regular Expressions in R