How to convert numeric levels of a factor into string in R data frame?

R ProgrammingServer Side ProgrammingProgramming

To convert numeric levels of a factor into string in R data frame, we can follow the below steps −

  • First of all, consider an in-built data set or create new one.

  • Then, use mutate function with ifelse to create string column based numeric column representing a factor.

Consider an-inbuilt data set

Let’s have a look at mtcars data set in base R −

 Live Demo

data(mtcars)
head(mtcars,25)

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

Output

                      mpg cyl disp hp drat wt qsec vs am gear carb
Mazda RX4              21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
Mazda RX4 Wag          21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4
Datsun 710             22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
Hornet 4 Drive         21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1
Hornet Sportabout      18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2
Valiant                18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
Duster 360             14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4
Merc 240D              24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
Merc 230               22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
Merc 280               19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4
Merc 280C              17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4
Merc 450SE             16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3
Merc 450SL             17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3
Merc 450SLC            15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3
Cadillac Fleetwood     10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4
Lincoln Continental    10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4
Chrysler Imperial      14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4
Fiat 128               32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
Honda Civic            30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
Toyota Corolla         33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
Toyota Corona         21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1
Dodge Challenger      15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2
AMC Javelin           15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2
Camaro Z28             13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4
Pontiac Firebird       19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2

Convert numeric factor into string

Loading dplyr package and converting values in gear column that represents a factor to string −

data(mtcars)
library(dplyr)
mtcars %>% arrange(gear) %>% mutate(gearW = ifelse(gear == 3, "Three",
ifelse(gear == 4, "Four", "Five")))

Output

                              mpg cyl disp hp drat wt qsec vs am gear carb gearW
Hornet 4 Drive                  21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 Three
Hornet Sportabout               18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 Three
Valiant                         18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 Three
Duster 360                      14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 Three
Merc 450SE                      16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3 Three
Merc 450SL                      17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3 Three
Merc 450SLC                     15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3 Three
Cadillac Fleetwood              10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4 Three
Lincoln Continental             10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4 Three
Chrysler Imperial               14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4 Three
Toyota Corona                   21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1 Three
Dodge Challenger                15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2 Three
AMC Javelin                     15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2 Three
Camaro Z28                      13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4 Three
Pontiac Firebird                19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2 Three
Mazda RX4                       21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 Four
Mazda RX4 Wag                   21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 Four
Datsun 710                      22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 Four
Merc 240D                       24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 Four
Merc 230                        22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 Four
Merc 280                        19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4 Four
Merc 280C                       17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4 Four
Fiat 128                        32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 Four
Honda Civic                     30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 Four
Toyota Corolla                  33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1 Four
Fiat X1-9                       27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1 Four
Volvo 142E                      21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2 Four
Porsche 914-2                   26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2 Five
Lotus Europa                    30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2 Five
Ford Pantera L                  15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4 Five
Ferrari Dino                    19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6 Five
Maserati Bora                   15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8 Five
raja
Published on 11-Aug-2021 07:30:46
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