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Build Bradley-Terry comparison data from pairwise results

Source: R/bt_model.R
build_bt_data.Rd

This function converts pairwise comparison results into the three-column format commonly used for Bradley-Terry models: the first two columns contain object labels and the third column contains the comparison result (1 for a win of the first object, 0 for a win of the second).

Usage

build_bt_data(results)

Arguments

results

A data frame or tibble with columns ID1, ID2, and better_id.

Value

A tibble with three columns:

  • object1: ID from ID1

  • object2: ID from ID2

  • result: numeric value, 1 if better_id == ID1, 0 if better_id == ID2

Rows with invalid or missing better_id are dropped.

Details

It assumes that the input contains columns ID1, ID2, and better_id, where better_id is the ID of the better sample. Rows where better_id does not match either ID1 or ID2 (including NA) are excluded.

Examples

results <- tibble::tibble(
  ID1       = c("S1", "S1", "S2"),
  ID2       = c("S2", "S3", "S3"),
  better_id = c("S1", "S3", "S2")
)

bt_data <- build_bt_data(results)
bt_data
#> # A tibble: 3 × 3
#>   object1 object2 result
#>   <chr>   <chr>    <dbl>
#> 1 S1      S2           1
#> 2 S1      S3           0
#> 3 S2      S3           1

# Using the example writing pairs
data("example_writing_pairs")
bt_ex <- build_bt_data(example_writing_pairs)
head(bt_ex)
#> # A tibble: 6 × 3
#>   object1 object2 result
#>   <chr>   <chr>    <dbl>
#> 1 S01     S02          0
#> 2 S01     S03          0
#> 3 S01     S04          0
#> 4 S01     S05          1
#> 5 S01     S06          0
#> 6 S01     S07          0