coalesce: A more versatile form of the T-SQL 'coalesce()' function.
In cvarrichio/rowr: Row-Based Functions for R Objects

Little more than a wrapper for vectorize, allows for duplication of SQL coalesce functionality, certain types of if-else statements, and apply/Reduce combinations.

1	coalesce(..., fun = (function(x, y) if (!is.na(x)) x else y))

`...`	an arbitrary number of `R` objects
`fun`	a two argument function that returns an atomic value

coalesce(c(NA,1,2))
coalesce(c(NA,1,2),c(3,4,NA))
df<-data.frame(a=c(NA,2,3),b=c(1,2,NA))
coalesce(df$a,df$b)
# Or even just:
coalesce(df)
# Coalesce can actually use any comparison.  For example, instead of non-NA
# values it could find the max in each row:
cbind(EuStockMarkets,Max=coalesce(EuStockMarkets,fun=function (x,y) if (x>y) x else y))