Error when I try to predict class probabilities in R - caret

Question

I\'ve build a model using caret. When the training was completed I got the following warning:

Warning message: In train.default(x, y, weights = w, ...) : A

Answer 1

The answer is in bold at the top of your post =]

What are you modeling? Is it alchemy_category? The code only says formula and we can't see it.

When you ask for class probabilities, model predictions are a data frame with separate columns for each class/level. If alchemy_category doesn't have levels that are valid column names, data.frame converts then to valid names. That creates a problem because the code is looking for a specific name but the data frame as a different (but valid) name.

For example, if I had

> test <- factor(c("level1", "level 2")) 
> levels(test)
[1] "level 2" "level1" 
> make.names(levels(test))
[1] "level.2" "level1"

the code would be looking for "level 2" but there is only "level.2".