dtplyr (version 1.1.0)

left_join.dtplyr_step: Join data tables

Description

These are methods for the dplyr generics left_join(), right_join(), inner_join(), full_join(), anti_join(), and semi_join(). The mutating joins (left, right, inner, and full) are translated to data.table::merge.data.table(), except for the special cases where it's possible to translate to [.data.table. Semi- and anti-joins have no direct data.table equivalent.

Usage

# S3 method for dtplyr_step
left_join(x, y, ..., by = NULL, copy = FALSE, suffix = c(".x", ".y"))

Arguments

x, y

A pair of lazy_dt()s.

...

Other parameters passed onto methods.

by

A character vector of variables to join by.

If NULL, the default, *_join() will perform a natural join, using all variables in common across x and y. A message lists the variables so that you can check they're correct; suppress the message by supplying by explicitly.

To join by different variables on x and y, use a named vector. For example, by = c("a" = "b") will match x$a to y$b.

To join by multiple variables, use a vector with length > 1. For example, by = c("a", "b") will match x$a to y$a and x$b to y$b. Use a named vector to match different variables in x and y. For example, by = c("a" = "b", "c" = "d") will match x$a to y$b and x$c to y$d.

To perform a cross-join, generating all combinations of x and y, use by = character().

copy

If x and y are not from the same data source, and copy is TRUE, then y will be copied into the same src as x. This allows you to join tables across srcs, but it is a potentially expensive operation so you must opt into it.

suffix

If there are non-joined duplicate variables in x and y, these suffixes will be added to the output to disambiguate them. Should be a character vector of length 2.

Examples

# NOT RUN {
library(dplyr, warn.conflicts = FALSE)

band_dt <- lazy_dt(dplyr::band_members)
instrument_dt <- lazy_dt(dplyr::band_instruments)

band_dt %>% left_join(instrument_dt)
band_dt %>% right_join(instrument_dt)
band_dt %>% inner_join(instrument_dt)
band_dt %>% full_join(instrument_dt)

band_dt %>% semi_join(instrument_dt)
band_dt %>% anti_join(instrument_dt)
# }