Changing a column's name to titlecase using dplyr, by means of a function-CodePudding

Consider the very simple example of renaming the lat column of quakes to Lat, the titlecase version.

library(dplyr)

quakes %>%
  rename(Lat = lat)

I would like to write this as a function. My attempt so far has been

titlecase_col <- function(df, col_name) {
  quakes %>%
    rename(tools::toTitleCase(as_string(ensym(col_name))) := {{col_name}})
}

> titlecase_col(quakes, lat)

Error: The LHS of `:=` must be a string or a symbol

The error doesn't make sense to me, since in my mind, that is a string, so I must be doing something wrong here.

CodePudding user response：

If we add the !! to evaluate and correct the syntax errors (input argument was df, whereas inside the function quakes was used - it could be a potential bug), it would work

titlecase_col <- function(df, col_name) {
  df %>%
    rename(!!tools::toTitleCase(rlang::as_string(ensym(col_name))) 
                  := {{col_name}})
}

-testing

> titlecase_col(quakes, lat) %>%
     head
     Lat   long depth mag stations
1 -20.42 181.62   562 4.8       41
2 -20.62 181.03   650 4.2       15
3 -26.00 184.10    42 5.4       43
4 -17.97 181.66   626 4.1       19
5 -20.42 181.96   649 4.0       11
6 -19.68 184.31   195 4.0       12