Concatenate string to data frame column

Question

I want to append to a data.frame the same string.

> df1 <- data.frame(pt1="a", pt2="b", row.names=1)
> df1
  pt1 pt2
1   a   b

As a result I would like to have:

   pt1                 pt2
1  Add this string a   Add this string b

Answer 1

We can use lapply

df1[] <- lapply(df1, function(x) paste('Add this string', x))

Or use Map

df1[] <- Map(paste, 'Add this string', df1)

Or

library(dplyr)
df1 %>%
     mutate_each(funs(paste('Add this string', .)))