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Extract pattern matches from text

Source: R/extract.R
extract.Rd

Uses a regex lookup table to extract at most one pattern match.

Usage

extract(
  data,
  col_name = "text",
  regex_table,
  pattern_col = "pattern",
  return_cols = NULL,
  regex_return_cols = NULL,
  date_col = NULL,
  date_start = NULL,
  date_end = NULL,
  remove_acronyms = FALSE,
  do_clean_text = TRUE,
  verbose = TRUE
)

Arguments

data

A data frame or character vector containing the text to search.

col_name

Column name in data frame containing text to search through.

regex_table

A regex lookup table with a pattern column.

pattern_col

Name of the regex pattern column in regex_table.

return_cols

Optional vector of column names to include from 'data'.

regex_return_cols

Optional vector of column names to include from 'regex_table'.

date_col

Optional column in 'data' for date filtering.

date_start

Optional start date for filtering 'data'.

date_end

Optional end date for filtering 'data'.

remove_acronyms

Logical; if TRUE, removes all-uppercase patterns from regex_table.

do_clean_text

Logical; if TRUE, applies basic text cleaning to the input before matching.

verbose

Logical; if TRUE, displays progress messages.

Value

A tibble (data frame) with the following columns:

  • All original columns from data (or subset specified by return_cols)

  • pattern The matched regex pattern

  • match The specific text extracted from the data

  • row_id Integer row identifier corresponding to the input data

  • Additional columns from regex_table if regex_return_cols specified

Details

Pattern matching is performed using R's regular expression engine and is case-insensitive by default. When multiple patterns match the same text, the first match is determined by the order of rows in regex_table.

Examples

# Create sample data
data <- data.frame(
  id = 1:3,
  text = c("I love apples", "Bananas are great", "Oranges and apples"),
  stringsAsFactors = FALSE
)

# Create regex patterns
patterns <- data.frame(
  pattern = c("apples", "bananas", "oranges"),
  category = c("fruit", "fruit", "fruit")
)

# Extract matches
extract(data, "text", patterns)
#> Matching 3 patterns against 3 text entries
#> 
  |                                                  | 0 % ~calculating  
  |+++++++++++++++++                                 | 33% ~00s          
  |++++++++++++++++++++++++++++++++++                | 67% ~00s          
  |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed=00s  
#> Number of matches found: 3
#> # A tibble: 3 × 5
#>      id text               pattern match   row_id
#>   <int> <chr>              <chr>   <chr>    <int>
#> 1     1 I love apples      apples  apples       1
#> 2     2 Bananas are great  bananas bananas      2
#> 3     3 Oranges and apples apples  apples       3