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rdplyruser-defined-functionstibble

How to use multiple variable from tibble in an user-defined function?


I have created a tibble consisting of 6 columns containing 6 different variables that will be input for a user defined function. I am new to r, and I don't know how to connect the tibble with user defined function. Please help.

I have replaced the complex user defined function with simple user_defined_function for the sake of discussion. `

library(tidyr)
library(dplyr)
rgb_val <- seq(from=0, to=255, by=10)
rgb_grid <- expand_grid(r1 = rgb_val, g1 = rgb_val, b1 = rgb_val,
                        r2 = rgb_val, g2 = rgb_val, b3 = rgb_val)

user_defined_function <- function(x) {
  x[,1] + x[,2] + x[,3] + x[,4] + x[,5] + x[,6]
}

rgb_grid %>% mutate(new_cols = user_defined_function ())

I want the results of the user_defined_function to be added as new column to the tibble rgb_grid. However, if what I have tried, unsuprisingly, throws an error.


Solution

  • Given you are passing the whole dataframe to the function, you can't use mutate. Rather, just pass the whole dataframe to the function and add that to your data.frame.

    (by the way I changed your rgb_val sequence to to = 20 otherwise the dataframe is huge -- are you trying to destroy my computer haha).

    Here's an approach with the tidyverse:

    rgb_grid %>% 
      bind_cols(setNames(user_defined_function(.), "new_col"))
    
    # A tibble: 729 × 7
          r1    g1    b1    r2    g2    b3 new_col
       <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>   <dbl>
     1     0     0     0     0     0     0       0
     2     0     0     0     0     0    10      10
     3     0     0     0     0     0    20      20
     4     0     0     0     0    10     0      10
     5     0     0     0     0    10    10      20
     6     0     0     0     0    10    20      30
     7     0     0     0     0    20     0      20
     8     0     0     0     0    20    10      30
     9     0     0     0     0    20    20      40
    10     0     0     0    10     0     0      10
    # … with 719 more rows
    

    Or with Base R

    new_col <- user_defined_function(rgb_grid) 
    cbind(rgb_grid, new_col)