Multiple merge via Reduce()

gistfile1.r

a <- data.frame(id = c(1,2,3,7,9), y1 = rnorm(5))
b <- data.frame(id = 1:3, y2 = rnorm(3))
c <- data.frame(id = 1:4, y3 = rnorm(4))

a
b
c

Reduce(function(x,y){merge(x, y, by.x = "id", by.y = "id", all = TRUE)}, 
       list(a, b, c), accumulate = FALSE)


## Source: http://rwiki.sciviews.org/doku.php?id=tips:data-frames:merge

## > Reduce(function(x,y){merge(x, y, by.x = "id", by.y = "id", all = TRUE)}, 
## +        list(a, b, c), accumulate = FALSE)
##   id         y1         y2          y3
## 1  1  0.3262975  0.1469356  0.04394575
## 2  2 -0.4525011 -1.3314288 -0.39520979
## 3  3  0.5057544 -0.5824310  0.50389474
## 4  4         NA         NA -1.38640045
## 5  7  0.5549681         NA          NA
## 6  9  0.8025466         NA          NA