Q:

Frequency histogram across multiple binary columns in ggplot2?

I have a data set like this: 
Var1 Var2 Var3
 1    NA    1
 1    NA    NA
 1    NA    NA
 NA   1    NA

The variables are binary, in different columns, and are not mutually exclusive.(It's from a "select all that apply" question).
I'm trying to get a histogram in ggplot2, but I can't figure out how to get the data in a good place to make this work. What am I missing? 
Thanks

A:

df = read.table(text="Var1 Var2 Var3
 1    NA    1
 1    NA    NA
 1    NA    NA
 NA   1    NA",
header=TRUE, stringsAsFactors=FALSE)

library(ggplot2)
Tab = data.frame(values=colSums(df, na.rm=TRUE), names = names(df))
ggplot(data=Tab, aes(x=names, y=values)) +
  geom_bar(stat="identity")

Or in base R
barplot(colSums(df, na.rm=TRUE))

