Selectively Rename R Data Frame Column Names Using a Key, Value Pair Dictionary

Question

I know there's an easy way to do this but I can't remember how I did it and can't find my notes. Basically I have a data frame with a bunch of column names. I also have a key,value pair data frame that has some new column names that need to replace the existing ones. I want to rename all of the columns that have a pair (and none that don't). So for example we can use mtcars:

x<-mtcars
idkey <- data.frame("original" =  c("cyl","hp"), "new" = c("cylinder", "horsepower"))

> head(x)
                   mpg cyl disp  hp drat    wt  qsec vs am gear carb
Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

> idkey
  original        new
1      cyl   cylinder
2       hp horsepower

I just want to replace the column names in x that exist in idkey. So after the replacement names(x) will go from this

> names(x)
 [1] "mpg"  "cyl"  "disp" "hp"   "drat" "wt"   "qsec" "vs"   "am"   "gear" "carb"

to this:

> names(x)
 [1] "mpg"  "cylinder"  "disp" "horsepower"   "drat" "wt"   "qsec" "vs"   "am"   "gear" "carb"

Note I would need this to only rename the columns which exist in the key, so some columns may not get renamed and they wouldn't be in any particular order.

Answer 1

dplyr::recode would also work:

colnames(x) <- dplyr::recode(
  colnames(x), 
  !!!setNames(as.character(idkey$new), idkey$original)
)

Answer 2

In this case, rename_at would be useful. Specify the variables to be renamed inside the vars from the 'original' column of 'idkey' (the columns are factor - so convert to character class with as.character - because the data.frame default option is stringsAsFactors = TRUE)

library(dplyr)
x %>%
    rename_at(vars(as.character(idkey$original)), ~ as.character(idkey$new)) %>%
    head(2)
#             mpg cylinder disp horsepower drat    wt  qsec vs am gear carb
#Mazda RX4      21        6  160        110  3.9 2.620 16.46  0  1    4    4
#Mazda RX4 Wag  21        6  160        110  3.9 2.875 17.02  0  1    4    4

Answer 3

We can use match in base R

names(x)[match(idkey$original, names(x))] <- idkey$new
head(x)

#                   mpg cylinder disp horsepower drat    wt  qsec vs am gear carb
#Mazda RX4         21.0        6  160        110 3.90 2.620 16.46  0  1    4    4
#Mazda RX4 Wag     21.0        6  160        110 3.90 2.875 17.02  0  1    4    4
#Datsun 710        22.8        4  108         93 3.85 2.320 18.61  1  1    4    1
#Hornet 4 Drive    21.4        6  258        110 3.08 3.215 19.44  1  0    3    1
#Hornet Sportabout 18.7        8  360        175 3.15 3.440 17.02  0  0    3    2
#Valiant           18.1        6  225        105 2.76 3.460 20.22  1  0    3    1

data

x<-mtcars
idkey <- data.frame("original" =  c("cyl","hp"), 
                    "new" = c("cylinder", "horsepower"), stringsAsFactors = FALSE)