[R] histogram with NAs

[darteta001 at ikasle.ehu.es]

Dear list,

I have a categorical variable in a data.frame that I would like to 
plot using a histogram to show number of events. Values are 0, 1 and 
some NAs. I can´t make the hist() function to 
1) include a column with the number of NAs
2) have the x axis to be categorical, I always get 0, 0.2, 0.4,... 1 
divisions

Can anyone help me?

This is my code. "database" is my data.frame and "Event" is my 
variable.
attach(database)
hist(Event, col = 2, main = "Number of Events"))

Thanks in advance,

David