Join two data.tables together

left_join(x, y, by = NULL, suffix = c(".x", ".y"), ..., keep = FALSE)

right_join(x, y, by = NULL, suffix = c(".x", ".y"), ..., keep = FALSE)

inner_join(x, y, by = NULL, suffix = c(".x", ".y"), ..., keep = FALSE)

full_join(x, y, by = NULL, suffix = c(".x", ".y"), ..., keep = FALSE)

anti_join(x, y, by = NULL)

semi_join(x, y, by = NULL)

Arguments

x: A data.frame or data.table
y: A data.frame or data.table
by: A character vector of variables to join by. If NULL, the default, the join will do a natural join, using all variables with common names across the two tables.
suffix: Append created for duplicated column names when using full_join()
...: Other parameters passed on to methods
keep: Should the join keys from both x and y be preserved in the output?

Examples

df1 <- data.table(x = c("a", "a", "b", "c"), y = 1:4)
df2 <- data.table(x = c("a", "b"), z = 5:6)

df1 %>% left_join(df2)
#> # A tidytable: 4 × 3
#>   x         y     z
#>   <chr> <int> <int>
#> 1 a         1     5
#> 2 a         2     5
#> 3 b         3     6
#> 4 c         4    NA
df1 %>% inner_join(df2)
#> # A tidytable: 3 × 3
#>   x         y     z
#>   <chr> <int> <int>
#> 1 a         1     5
#> 2 a         2     5
#> 3 b         3     6
df1 %>% right_join(df2)
#> # A tidytable: 3 × 3
#>   x         y     z
#>   <chr> <int> <int>
#> 1 a         1     5
#> 2 a         2     5
#> 3 b         3     6
df1 %>% full_join(df2)
#> # A tidytable: 4 × 3
#>   x         y     z
#>   <chr> <int> <int>
#> 1 a         1     5
#> 2 a         2     5
#> 3 b         3     6
#> 4 c         4    NA
df1 %>% anti_join(df2)
#> # A tidytable: 1 × 2
#>   x         y
#>   <chr> <int>
#> 1 c         4