mget2: enhanced mget
In drmjc/macsR: Facilitate analysis of MACS results.

Description Usage Arguments Value TODO Author(s) Examples

Enchanced mget to look up x in y. Changes in addition to mget include:
* Values can be sorted alphanumerically
* Since some keys have multiple values, this function returns all, just the first (hint; use first=TRUE, sort=TRUE), assuming that the first is the oldest, or all values collapsed into a single string.
* keys in x are allowed to be NA (hint: na.rm=FALSE)

1 2	mget2(x, y, sort = TRUE, first = TRUE, na.rm = TRUE, collapse = NULL)

`x`	a vector of keys, `NA`'s allowed.
`y`	an env, or AnnDbBimap, or ProbeAnnDbBimap
`sort`	logical: if `TRUE`, then sort the values for each key
`first`	logical: if `TRUE`, then choose the first value for each key, after the optional sort
`na.rm`	logical: remove those keys that had no matches? if `TRUE`, a vector with no `NA`'s will be returned. if `FALSE`, then return a list of key to value maps, possibly with `NA`'s.
`collapse`	specify a character(1), eg “", "” to collapse multiple values into a single `character`. Useful if you want to report all multi-mapping values. Note that this is ignored if first=TRUE, and that this will always return a character

either a vector or list of values, depending on the value of na.rm, and collapse

provide more sorting options to choose the newest.

Mark Cowley, 2011-08-25

if( require(org.Hs.eg.db) ) {
  sym <- c("TP53", "INS", "EGFR", "MET", NA)
  mget2(sym, org.Hs.egSYMBOL2EG)
  mget2(sym, org.Hs.egSYMBOL2EG, na.rm=FALSE)
}