Johnny Johansson - 4 months ago 23

R Question

Lets say I have 3 factors, each has 2 levels: 'a' and 'b':

`> b <- factor(c('b', 'b', 'a'))`

> a <- factor(c('a', 'b', 'a'))

> c <- factor(c('a', 'a', 'a'))

I want to create fourth factor that on every position contains the most common element from this 3 factors, so, in this example, it would look like this:

`> d`

[1] a b a

Levels: a b

Is there a way of performing this kind of operation with some "smooth" function, or do I have to use "if" conditions?

Answer

We can try

```
factor(apply(data.frame(b, a, c), 1, Mode), levels = levels(a))
#[1] a b a
#Levels: a b
```

where `Mode`

is

```
Mode <- function(x) {
ux <- unique(x)
ux[which.max(tabulate(match(x, ux)))]
}
```