Skip to contents

Search for Candidate Matches Between Tables

Source: R/generics_core.R
search_candidates.Rd

Find candidate matches between two tables: for each record on one side, the records on the other side that share enough rare, informative token content to score at or above the threshold. This is the cross-table counterpart of detect_duplicates().

Pass a search_strategy() for fuzzy, scored matching, or an exact_strategy() to keep only pairs whose token sets are identical.

Usage

search_candidates(base_table, target_table, base_id, target_id, strategy, ...)

Arguments

base_table

A data.frame, tibble, data.table, or backend table.

target_table

The table to search against.

base_id

Character scalar naming the ID column in base_table.

target_id

Character scalar naming the ID column in target_table.

strategy

A Search_Strategy (or Exact_Strategy) describing how to tokenize each column, how to block, and the matching threshold.

...

Additional arguments passed to backend-specific methods, such as threshold and weights.

Value

A table with two rows per matched pair (one for the base record, one for the target record), sharing a match_id:

match_id

Identifier shared by the two rows of a matched pair.

score

The pair's match score.

source

"base" or "target".

id

The record ID.

<original columns>

Every other column from the source table.

rank

Rank of this candidate among a record's matches.

See also

detect_duplicates() for the within-table version, extract_unmatched() for the residual, multi_stage_search() for staged passes.

Examples

data(base_example)
data(target_example)

strat <- search_strategy(
  Nachname ~ normalize_text() + word_tokens(min_nchar = 3),
  Vorname  ~ normalize_text() + word_tokens(min_nchar = 3),
  Ort      ~ normalize_text(),
  block_by = "Kreis",
  threshold = 0.8
)

matches <- search_candidates(
  base_example, target_example,
  base_id = "id_base", target_id = "id_target",
  strategy = strat
)
head(matches)
#> # A tibble: 6 × 14
#>   id    match_id score source id_base Vorname Nachname Strasse  Hausnummer Ort  
#>   <chr>    <int> <dbl> <chr>  <chr>   <chr>   <chr>    <chr>    <chr>      <chr>
#> 1 B0003        1     1 base   B0003   Peter   Becker   Turmstr… 147        Sind…
#> 2 T0003        1     1 target NA      Peter   Becker   Turmstr… 147        Sind…
#> 3 B0005        2     1 base   B0005   Sarah   Schmidt  Willy-B… 13         Köln 
#> 4 T0005        2     1 target NA      Sarah   Schmidt  Willy-B… 13         Köln 
#> 5 B0010        3     1 base   B0010   Michael Wagner   Dorfstr… 20         Bad …
#> 6 T0010        3     1 target NA      Michael Wagner   Dorfstr… 20         Bad …
#> # ℹ 4 more variables: Kreis <chr>, actual_link <chr>, id_target <chr>,
#> #   rank <int>