Passing col_names of a data frame in a function IN R

Question

i want to create a function that calculte the rate of missing values of a data frame's column.

here's my code :

Pourcentage_NA = function(df, col_Name){
  
  
  res=100*( length(df[col_Name])-length(na.omit(df[col_Name])) ) / length(df[col_Name])
}

when I call it like this : x = Pourcentage_NA( Data , "A" ) It shows that x=0 although I know there's some missing values. Anyone can help me pls ?

I try to change the formula but it keep saying the same thing

Answer 1

You can do:

Pourcentage_NA = function(df, col_Name){
  100 * sum(is.na(df[col_Name])) / nrow(df)
}

Testing, we have:

dat <- data.frame(A = c(1, NA, 3, NA), B = c(NA, 2, 3, 4))

Pourcentage_NA(dat, "A")
#> [1] 50
Pourcentage_NA(dat, "B")
#> [1] 25

An alternative would be

Pourcentage_NA <- function(df, col_Name) 100 * colMeans(is.na(df))[col_Name]

Pourcentage_NA(dat, "A")
#>  A 
#> 50
Pourcentage_NA(dat, "B")
#>  B 
#> 25

^{Created on 2022-11-13 with reprex v2.0.2}