Dplyr or Magrittr - tolower?

Question

Is it possible to set all column names to upper or lower within a dplyr or magrittr chain?

In the example below I load the data and then, using a magrittr pipe, chain it through to my dplyr mutations. In the 4th line I use the tolower function , but this is for a different purpose: to create a new variable with lowercase observations.

mydata <- read.csv('myfile.csv') %>%
    mutate(Year = mdy_hms(DATE),
           Reference = (REFNUM),
           Event = tolower(EVENT)

I'm obviously looking for something like colnames = tolower but know this doesn't work/exist.

I note the dplyr rename function but this isn't really helpful.

In magrittr the colname options are:

set_colnames instead of base R's colnames<-
set_names instead of base R's names<-

I've tried numerous permutations with these but no dice.

Obviously this is very simple in base r.

names(mydata) <- tolower(names(mydata))

However it seems incongruous with the dplyr/magrittr philosophies that you'd have to do that as a clunky one liner, before moving on to an elegant chain of dplyr/magrittr code.

See [@Moody_Mudskipper's](https://stackoverflow.com/users/2270475/moody-mudskipper) answer to learn more about `dplyr::rename_all()`. — Cristian E. Nuno, Aug 21 '18 at 17:50

moodymudskipper · Answer 1 · 2023-04-11T07:06:33.757

71

with {dplyr} we can do :

mydata %>% rename_with(tolower)

rename_all() can be used for the same effect but has been superseded.

edited Apr 11 '23 at 07:06

answered Jul 03 '17 at 10:09

moodymudskipper

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seems to be limited by the number of columns: – user1767316 Dec 06 '19 at 21:55
I don't see that with 10k columns, how many columns do you have ? – moodymudskipper Dec 16 '19 at 15:24
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in my case 5505 col and 19425 rows but I forgot that it is a spark rdd accessed through sparklyr …. – user1767316 Dec 17 '19 at 23:26

score 25 · Answer 2 · answered Mar 25 '15 at 18:48

25

iris %>% setNames(tolower(names(.))) %>% head

Or equivalently use replacement function in non-replacement form:

iris %>% `names<-`(tolower(names(.))) %>% head
iris %>% `colnames<-`(tolower(names(.))) %>% head  # if you really want to use `colnames<-`

answered Mar 25 '15 at 18:48

BrodieG

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score 22 · Accepted Answer · answered Mar 25 '15 at 20:02

22

Using magrittr's "compound assignment pipe-operator" %<>% might be, if I understand your question correctly, an even more succinct option.

library("magrittr")
names(iris) %<>% tolower

?`%<>%` # for more

answered Mar 25 '15 at 20:02

Kevin

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score 2 · Answer 4 · answered Mar 25 '15 at 22:33

2

mtcars %>% 
set_colnames(value = casefold(colnames(.), upper = FALSE)) %>% 
head

casefold is available in base R and can convert in both direction, i.e. can convert to either all upper case or all lower case by using the flag upper, as need might be.

Also colnames() will use only column headers for case conversion.

answered Mar 25 '15 at 22:33

Frash

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*casefold is a wrapper for tolower and toupper provided for compatibility with S-PLUS.* – Rich Scriven Mar 25 '15 at 23:37

score 2 · Answer 5 · answered Nov 15 '16 at 16:22

2

You could also define a function:

upcase <- function(df) {
  names(df) <- toupper(names(df))
  df
}

library(dplyr)

mtcars %>% upcase %>% select(MPG)

answered Nov 15 '16 at 16:22

Carl

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IMHO it's best solution. I named this function `names_to_upper` (and second as `names_to_lower`), `colnames_` would look good too: `mtcars %>% colnames_to_upper %>% select(MPG)`. – Marek Nov 23 '16 at 08:41

Dplyr or Magrittr - tolower?

5 Answers5