concatenate two lists of string and attach index in r

Question

Here is my sample:

stringa = c("a","b","c")
stringb = c("high","low","average")
index = c(1,2,3)

data <- data.frame(stringa,stringb,index)

I would like to concatenate stringa and stringb, and attach the corresponding index in another column. For example, the first row of the result should be "a high" with index "1".

Now I have used this function to concatenate the two strings:

c(outer(a, b, paste))

What happened? Was it not as expected? – talat Jul 06 '17 at 14:17 — talat, Jul 06 '17 at 14:17

Y.L · Answer 1 · 2017-07-06T16:05:06.930

For "a high", "b low", "c average" you can do:

stringa = c("a","b","c")
stringb = c("high","low","average")
index = c(1,2,3)
data.frame(concatenated = paste(stringa, stringb),index)
  concatenated
1    a high
2    b low
3    c average

For the full permutations of stringa and stringb:

stringa = c("a","b","c")
stringb = c("high","low","average")
data.frame(concatenated = c(outer(stringa, stringb, paste) ) )
    concatenated
1       a high
2       b high
3       c high
...
9    c average

If you want to explicitly add the row index:

df = data.frame(concatenated = c(outer(stringa, stringb, paste) ) )
df$index = rownames(df)
df 
  concatenated index
1       a high     1
2       b high     2
3       c high     3
...
9    c average     9

I also need to concatenate "a" with "low" and "average" – Ran Tao Jul 06 '17 at 14:46 — Ran Tao, Jul 06 '17 at 14:46

concatenate two lists of string and attach index in r

1 Answers1