‘!’ not meaningful for factors in R

Question

I need to exclude the variable \"PABI\" from my data frame. So, I am subsetting as follow:

MyData4 <- subset(MyData, PROV==\"PABI\")
newdata <- MyData[!MyD         


        

Answer 1

Why not just do:

newdata <- subset(MyData, PROV!="PABI")

Answer 2

! only applies to logical variables. However, your subset call returns a data.frame, not a logical; hence the error. In reality, you just need to invert the condition in your first line:

newdata <- subset(MyData, PROV != "PABI")

That’s it.

Just to clarify how logical values work, you could also write the following:

has_PABI <- MyData$PROV == "PABI"
newdata <- MyData[! has_PABI]

Notice that the second line is now identical to your code. What changed is that the variable you as a negative index is now a logical vector, containing the values TRUE or FALSE for each row, depending on the value of that row’s PROV column.