How to paste a string on each element of a vector of strings using apply in R?

Question

I have a vector of strings.

d <- c("Mon","Tues","Wednes","Thurs","Fri","Satur","Sun")

for which I want to paste the string "day" on each element of the vector in a way similar to this.

week <- apply(d, "day", paste, sep='')

score 118 · Accepted Answer · answered Aug 08 '11 at 15:51

118

No need for apply(), just use paste():

R> d <- c("Mon","Tues","Wednes","Thurs","Fri","Satur","Sun")
R> week <- paste(d, "day", sep="")
R> week
[1] "Monday"    "Tuesday"   "Wednesday" "Thursday"  
[4] "Friday"    "Saturday"  "Sunday"   
R>

answered Aug 08 '11 at 15:51

Dirk Eddelbuettel

360,940
56
644
725

12

Shorter form: `week <- paste0(d, "day")` – Gürol Canbek Jul 12 '17 at 19:47
21

Sure. But please account for the fact that `paste0()` did *not* exist when I wrote the answer six years ago. – Dirk Eddelbuettel Jul 12 '17 at 19:48

Andrie · Answer 2 · 2011-08-08T15:58:46.830

14

Other have already indicated that since paste is vectorised, there is no need to use apply in this case.

However, to answer your question: apply is used for an array or data.frame. When you want to apply a function over a list (or a vector) then use lapply or sapply (a variant of lapply that simplifies the results):

sapply(d, paste, "day", sep="")
        Mon        Tues      Wednes       Thurs         Fri       Satur 
   "Monday"   "Tuesday" "Wednesday"  "Thursday"    "Friday"  "Saturday" 
        Sun 
   "Sunday"

edited Aug 08 '11 at 15:58

answered Aug 08 '11 at 15:52

Andrie

176,377
47
447
496

1

@pedrosaurio I have to point out that if you use `sapply` for this specific problem it would be hugely inefficient. Use the already vectorised form of `paste`, as @DirkEddelbuettel suggested. – Andrie Aug 08 '11 at 16:40
@DirkEddelbuettel Thanks, I was at first a bit confused for which answer I should tick as the good one. As Andrie's answer was the 'real' answer I thought that it should be selected as the good one but if it is a wrong method and it will create confusion for future reference I'll then change it. Thanks again – pedrosaurio Aug 09 '11 at 09:16

score 7 · Answer 3 · answered Sep 26 '19 at 07:24

Apart from paste/paste0 there are variety of ways in which we can add a string to every element in the vector.

1) Using sprintf

sprintf("%sday", d)
#[1] "Monday"    "Tuesday" "Wednesday" "Thursday"  "Friday"  "Saturday"  "Sunday"

2) glue

glue::glue("{d}days")

Here {d} is evaluated as R code. This can be wrapped in as.character if needed.

3) str_c in stringr

stringr::str_c(d, "day")

whose equivalent is

4) stri_c in stringi

stringi::stri_c(d, "day")

5) stringi also has stri_paste

stringi::stri_paste(d, "day")

How to paste a string on each element of a vector of strings using apply in R?

3 Answers3

Linked

Related