lj: Lower join
In HikaGenji/fql: Functional Query Language

Description Usage Arguments Value Author(s) See Also Examples

The lj (left join) verb joins tables on the key columns of its right argument. The left argument is a table, and the right argument is a keyed table, where the key columns must be a subset of the columns of the left argument.

1	lj(x, y, keep.y=FALSE)

`x`	A dataframe.
`y`	A keyed dataframe. key attribute can be set by xkey function.
`keep.y`	a boolean whether or not keeping non matching y records in the result

A dataframe

JFP

uj and xkey

  x <- data.frame(a=c(1,2,3),
                  b=c("x", "y", "z"),
                  c=c(10, 20, 20)
  )
  y <- data.frame(a=c(1,3),
                  b=c("x", "z"),
                  c=c(1,2),
                  d=c(10,20))
  
  x %>% lj(y %>% xkey(c("a", "b")))