Add column in base R, imputing with zeros

impute_and_sum_demo.R

df <- data.frame(
  id    = 1:5,
  label = LETTERS[1:5],  # A, B, C, D, E
  gen_1 = c(1.0, 1.1, NA, 1.3, NA),
  gen_2 = c(2.0, NA, 2.2, 2.3, NA),
  gen_3 = c(3.1, NA, 3.2, NA, NA)
)

# take a look
df
#>   id label gen_1 gen_2 gen_3
#> 1  1     A   1.0   2.0   3.1
#> 2  2     B   1.1    NA    NA
#> 3  3     C    NA   2.2   3.2
#> 4  4     D   1.3   2.3    NA
#> 5  5     E    NA    NA    NA

# replace NAs with 0 before summing
impute_and_sum <- function(x, y, z) {
  x <- ifelse(is.na(x), 0, x)
  y <- ifelse(is.na(y), 0, y)
  z <- ifelse(is.na(z), 0, z)
  
  x + y + z
}

# test it out
impute_and_sum(df$gen_1, df$gen_2, df$gen_3)
#> [1] 6.1 1.1 5.4 3.6 0.0

# put it in the df
df$gen_total <- impute_and_sum(df$gen_1, df$gen_2, df$gen_3)

# tada!
df
#>   id label gen_1 gen_2 gen_3 gen_total
#> 1  1     A   1.0   2.0   3.1       6.1
#> 2  2     B   1.1    NA    NA       1.1
#> 3  3     C    NA   2.2   3.2       5.4
#> 4  4     D   1.3   2.3    NA       3.6
#> 5  5     E    NA    NA    NA       0.0