CODEWITHSUNDEEP
rlogical-operators
traviata
traviata

Reputation: 27

Logical expression evaluating to NA

In R, I have a function Outlier that accepts a numerical vector of length 3. I was trying this:

Outlier <- function(x) {
  x <- sort(x)
  if((x[1] < 1e-2) %% (x[1] > 1e-4))) {
print(x)
  }
...

However, I was getting the error message "Error in if (condition) { : argument is not interpretable as logical". After debugging, I found that the error was being produced whenever x[1] == 0. Somehow when x[1] == 0, the logical expression evaluates to NA. With other values it works as expected. Why is this, and how can I prevent it?

Upvotes: 0

Views: 94

Answers (1)

Rui Barradas
Rui Barradas

Reputation: 76402

To prevent this you should revise your goal. The NA doesn't show up only when x[1] is zero, it shows up whenever x[1] > 1e-4 evaluates to FALSE.

TRUE %% FALSE
[1] NA
FALSE %% FALSE
[1] NA

This obviously makes sense, I was only surprised to see it not return NaN:

1 %% 0
[1] NaN
0 %% 0
[1] NaN

Which leads me to conclude that the R parser is clever enough to recognize the difference between logical and numerical values.

Upvotes: 2

Related Questions