Subtraction between columns in R-CodePudding

I have following dataframe.

act	tar
4	3
NA	NA
-5	-4
0	0
NA	3

To subtract column tar from column act i used following code. But it gives me error.

df <- df %>%
   mutate(diff = if_else(!is.na(act) & !is.na(tar), act - tar, as.integer(NA))

I checked the class of both columns, and they are integer. Can anyone please help me?

CodePudding user response：

base R option:

df <- data.frame(act = c(4, NA, -5, 0, NA),
                 tar = c(3, NA, -4, 0, 3))

df$diff <- (df$act - df$tar)
df
#>   act tar diff
#> 1   4   3    1
#> 2  NA  NA   NA
#> 3  -5  -4   -1
#> 4   0   0    0
#> 5  NA   3   NA

^{Created on 2022-07-09 by the reprex package (v2.0.1)}

If you want to take the NA in account, you can write a function and apply that on your columns like this:

df <- data.frame(act = c(4, NA, -5, 0, NA),
                 tar = c(3, NA, -4, 0, 3))

minus <- function(x) sum(x[1],na.rm=T) - sum(x[2],na.rm=T)

df$diff <- apply(df[,c('act','tar')],1, function(x) sum(x[1],na.rm=T) - sum(x[2],na.rm=T))
df
#>   act tar diff
#> 1   4   3    1
#> 2  NA  NA    0
#> 3  -5  -4   -1
#> 4   0   0    0
#> 5  NA   3   -3

^{Created on 2022-07-09 by the reprex package (v2.0.1)}

CodePudding user response：

A possible solution:

library(dplyr)

df %>% 
  mutate(z = act - tar)

#>   act tar  z
#> 1   4   3  1
#> 2  NA  NA NA
#> 3  -5  -4 -1
#> 4   0   0  0
#> 5  NA   3 NA

CodePudding user response：

Using coalesce you can get get the Non-NA value

df |> 
  mutate(diff = ifelse(is.na(act - tar), coalesce(act, -tar), act - tar))

  act tar diff
1   4   3    1
2  NA  NA   NA
3  -5  -4   -1
4   0   0    0
5  NA   3   -3

CodePudding user response：

Your code is almost right, only a little problem, the "true" and "false" conditions should be the same type, and you missied one ")"

     df <- df %>% mutate(diff = if_else((!is.na(act) & !is.na(tar)), as.integer(act - tar), as.integer(NA)))
 df
A data.frame: 5 × 3
act tar diff
<dbl>   <dbl>   <int>
4   3   1
NA  NA  NA
-5  -4  -1
0   0   0
NA  3   NA

you can also try this

    df <- df %>% mutate(diff = act - tar)