I need some help here.
I have some data in which every entry can take one or more levels of a categorical variable. for example, I have a category with 3 levels:
entry category 1 A, B, C 2 B 3 C, A, B
How should I organized it into a file in order to easily let R discriminate among levels in order to do my analysis. Something like this:
Categories entries other_results A 2 ~ B 3 ~ C 2 ~
I thought about doing a comma separated list, as shown in the example 1. But then what should I do in R in order to transform those string into categories?
CLARIFICATION: I'd like to avoid creating a column for every level. This variable has many levels and many other variables are already present. This would make the file uselessly big and not readable easily by humans.