matchval: Lookup a value
In phytomosaic/ecole: ecole: School of Ecology Package

Description Usage Arguments Details Value See Also Examples

Lookup a value based on matching IDs among two data.frames.

1	matchval(x, y, val = NULL, xid = NULL, yid = NULL)

`x`	data.frame containing values of interest.
`y`	data.frame to be matched.
`val`	character, name of column containing values in `x`.
`xid`	character, name of ID column in `x`.
`yid`	character, name of ID column in `y`.

Similar to vlookup function found elsewhere. Returns NA if no match is found. If any IDs are duplicated, then only the first matching value is returned (just like match).

Values from x$val, ordered by y$yid.

match.

x <- data.frame(ident = letters[1:7], foo = rnorm(7))
y <- data.frame(ident = letters[5:9], bar = rnorm(5))
y$foo <- matchval(x, y, 'foo')
x
y

# be careful you use the intended column name!
colnames(y)[1] <- 'identifier'
matchval(x, y, 'foo')  # wrongly matches on existing 'foo' column
matchval(x, y, 'foo', 'ident', 'identifier')  # correct