concatenate two lists of string in r

Question

Here is my sample:

a = c("a","b","c")
b = c("1","2","3")

I need to concatenate a and b automatically. The result should be "a 1","a 2","a 3","b 1","b 2","b 3","c 1","c 2","c 3".

For now, I am using the paste function:

paste(a[1],b[1])

I need an automatic way to do this. Besides writing a loop, is there any easier way to achieve this?

JasonWang · Accepted Answer · 2017-06-08 21:44:21Z

3

c(outer(a, b, paste))

# [1] "a 1" "b 1" "c 1" "a 2" "b 2" "c 2" "a 3" "b 3" "c 3"

answered Jun 8, 2017 at 21:44

JasonWang

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1 Comment

outer FTW ! I always forget that function :)

digEmAll · Accepted Answer · 2017-06-08 21:41:08Z

2

Other options are :

paste(rep.int(a,length(b)),b)

or :

with(expand.grid(b,a),paste(Var2,Var1))

answered Jun 8, 2017 at 21:41

digEmAll

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Bea · Accepted Answer · 2017-06-08 21:35:45Z

2

You can do:

c(sapply(a, function(x) {paste(x,b)}))
[1] "a 1" "a 2" "a 3" "b 1" "b 2" "b 3" "c 1" "c 2" "c 3"

edited paste0 into paste to match OP update

answered Jun 8, 2017 at 21:30

Bea

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