specifying the name of a new variable used in mutate() from a function

user_16762740 0
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I was wondering if there might be a way to specify the name of a new variable used in mutate() (argument mutate_nm = "bb") inside the foo() function below?

library(tidyverse)

foo <- function(data = mtcars, mutate_nm, val = 12){
  
  mutate(mutate_nm = val)
  
}
#==== EXAMPLE OF USE:

foo(mutate_nm = "bb") Doesn't produce a dataframe with a new column named `"bb"`
dplyr tidyverse dataframe r function
1 Answers

We need to use := with !! or {{}}. Also, mutate by itself doesn't create any column i.e. need the data argument as well

foo <- function(data = mtcars, mutate_nm, val = 12){
  data %>%
     mutate({{mutate_nm}} := val)
     #or use
     #mutate(!! mutate_nm := val)
  
}

-testing

> foo(mtcars, "bb")
                     mpg cyl  disp  hp drat    wt  qsec vs am gear carb bb
Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4 12
Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4 12
Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1 12
Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1 12
Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2 12
Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1 12
Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4 12
Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2 12
Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2 12
Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4 12
Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4 12
Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3 12
Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3 12
Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3 12
Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4 12
Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4 12
Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4 12
Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1 12
Honda Civic         30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2 12
Toyota Corolla      33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1 12
Toyota Corona       21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1 12
Dodge Challenger    15.5   8 318.0 150 2.76 3.520 16.87  0  0    3    2 12
AMC Javelin         15.2   8 304.0 150 3.15 3.435 17.30  0  0    3    2 12
Camaro Z28          13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4 12
Pontiac Firebird    19.2   8 400.0 175 3.08 3.845 17.05  0  0    3    2 12
Fiat X1-9           27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1 12
Porsche 914-2       26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2 12
Lotus Europa        30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2 12
Ford Pantera L      15.8   8 351.0 264 4.22 3.170 14.50  0  1    5    4 12
Ferrari Dino        19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6 12
Maserati Bora       15.0   8 301.0 335 3.54 3.570 14.60  0  1    5    8 12
Volvo 142E          21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2 12
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