Reverse the content of certain rows of specific columns based on a 3rd column in R-CodePudding

My data frame looks like this:

library(tidyverse)
df <- tibble(col1=c(1,10,100,40,1000), col2=c(15,20,50,80,2000), 
             direction=c(" "," ","-"," "," "), score=c(50,100,300,10,300))
df 
#> # A tibble: 5 × 4
#>    col1  col2 direction score
#>   <dbl> <dbl> <chr>     <dbl>
#> 1     1    15              50
#> 2    10    20             100
#> 3   100    50 -           300
#> 4    40    80              10
#> 5  1000  2000             300

^{Created on 2022-07-29 by the reprex package (v2.0.1)}

I want when the direction is " - " to reverse the content of the col1 and col2,
so my data looks like this.

#>    col1  col2 direction score
#>   <dbl> <dbl> <chr>     <dbl>
#> 1     1    15              50
#> 2    10    20             100
#> 3    50   100             300
#> 4    40    80              10
#> 5  1000  2000             300

#>    col1  col2 direction score new_col1 new_col2 new_direction 
#>   <dbl> <dbl> <chr>     <dbl>
#> 1     1    15              50    1         15           
#> 2    10    20             100    10        20           
#> 3    100   50 -           300    50        100          
#> 4    40    80              10    40        80           
#> 5  1000  2000             300   1000       2000

CodePudding user response：

For both, you could use transform:

df |>
  transform(col1 = ifelse(direction == "-", col2, col1),
            col2 = ifelse(direction == "-", col1, col2),
            direction = " ")

df |>
  transform(col1_new = ifelse(direction == "-", col2, col1),
            col2_new = ifelse(direction == "-", col1, col2),
            direction_new = " ")

The second can easily be done with mutate in a similar fashion:

library(dplyr)

df |> 
  mutate(col1_new = if_else(direction == "-", col2, col1),
         col2_new = if_else(direction == "-", col1, col2),
         direction_new = " ")

But in order to do the first in dplyr it won't be as elegant as transform. You'll probably need an intermediate variable.

Output:

  col1 col2 direction score
1    1   15              50
2   10   20             100
3   50  100             300
4   40   80              10
5 1000 2000             300

  col1 col2 direction score col1_new col2_new direction_new
1    1   15              50        1       15              
2   10   20             100       10       20              
3  100   50         -   300       50      100              
4   40   80              10       40       80              
5 1000 2000             300     1000     2000