Collapse pasting in R

January 30, 2012
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(This article was first published on The Geokook. » R, and kindly contributed to R-bloggers)

How do you take a vector in R, and paste the individual elements together?  Easy, a loop.  No, bad! **slap on the wrist**  Here’s an example why not.  

So let’s start by concatenating a few character strings and showing some examples using base::paste:

a <- c("something", "to", "paste")
[1] "something" "to" "paste" 
> paste(a, sep="_") 
[1] "something" "to" "paste"
> paste(a, collapse="_") 
[1] "something_to_paste"
> paste(a, sep="_", collapse="-")
[1] "something-to-paste"

And there we have it, a simple example demonstrating the difference between a separator expression and a collapse expression without using a hideous loop.  

So finally the moral: read the help pages!


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