filter_joins {poorman}

Filtering joins filter rows from x based on the presence or absence of matches in y:

Description

• semi_join() return all rows from x with a match in y.

• anti_join() return all rows from x without a match in y.

Usage

anti_join(x, y, by = NULL)

semi_join(x, y, by = NULL)

Arguments

x, y

The data.frames to join.

by

A character vector of variables to join by. If NULL, the default, ⁠*_join()⁠ will do a natural join, using all variables with common names across the two tables. A message lists the variables so that you can check they're right (to suppress the message, simply explicitly list the variables that you want to join).

Examples

table1 <- data.frame(
  pupil = rep(1:3, each = 2),
  test = rep(c("A", "B"), 3),
  score = c(60, 70, 65, 80, 85, 70),
  stringsAsFactors = FALSE
)
table2 <- table1[c(1, 3, 4), ]

table1 %>% anti_join(table2, by = c("pupil", "test"))
table1 %>% semi_join(table2, by = c("pupil", "test"))