[R] Count missing variables in dataset

Achim Zeileis
Mon, 21 Mar 2005 11:37:18 -0000

On Mon, 21 Mar 2005 12:07:16 +0100 Jan Sabee wrote:

> I have a problem about how to count missing variables in dataset.
> I have a question for my customer. They are must choice one of answer
> for example: A, B, C, D and E.
> Now, I have dataset which is the result from my question, for
> instance:
>
> x1 x2 x3 x4 x5
> A  A  A   B  A
> C  A  A   A  A
> B  B  A   B  A
> B  B  B   C  A
> A  B  B   B  B
> C  B  B   B  A
>
> I know that my customer only choice A, B and C.
> Are there any way to count variables that are not include in dataset.
> I mean D and E is missing in dataset.

You just need to set up the variables properly. If you just say:

R> x <- factor(sample(LETTERS[1:3], 5, replace = TRUE))
R> summary(x)
A B C
1 2 2

R will assume that the only levels available are A-C. But if you tell R

R> x <- factor(x, levels = LETTERS[1:5])
R> summary(x)
A B C D E
1 2 2 0 0

it will do what you want. Just provide the full choice set as levels to
the corresponding variables.
Z

> Thanks for your help.
> Jan Sabee
>
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