pairwise_pmi {widyr}

Pointwise mutual information of pairs of items

Description

Find pointwise mutual information of pairs of items in a column, based on a "feature" column that links them together. This is an example of the spread-operate-retidy pattern.

Usage

pairwise_pmi(tbl, item, feature, sort = FALSE, ...)

pairwise_pmi_(tbl, item, feature, sort = FALSE, ...)

Arguments

tbl

Table

item

Item to compare; will end up in item1 and item2 columns

feature

Column describing the feature that links one item to others

sort

Whether to sort in descending order of the pointwise mutual information

...

Extra arguments passed on to squarely, such as diag and upper

Value

A tbl_df with three columns, item1, item2, and pmi.

Examples

library(dplyr)

dat <- tibble(group = rep(1:5, each = 2),
              letter = c("a", "b",
                         "a", "c",
                         "a", "c",
                         "b", "e",
                         "b", "f"))

# how informative is each letter about each other letter
pairwise_pmi(dat, letter, group)
pairwise_pmi(dat, letter, group, sort = TRUE)