如何使用在R中的apply将字符串粘贴到字符串向量的每个元素上？

Question

我有一个字符串向量.

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

我希望以类似于此的方式将字符串"day"粘贴到矢量的每个元素上.

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

Answer 1

不需要apply(),只需使用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> 

Answer 2

其他已经表明,由于paste是矢量化的,因此apply在这种情况下不需要使用.

但是,要回答您的问题: apply用于数组或data.frame.如果你想申请一个列表(或载体)的函数,然后使用lapply或sapply(的变体lapply是简化的结果):

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

Answer 3

除了paste/之外paste0，我们还可以通过多种方式向向量中的每个元素添加字符串。

1）使用sprintf

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

2）glue

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

这里{d}被评估为 R 代码。as.character如果需要的话可以将其包裹起来。

3）str_c在stringr

stringr::str_c(d, "day")

其等价物是

4stri_c进stringi

stringi::stri_c(d, "day")

5）stringi还有stri_paste

stringi::stri_paste(d, "day")