You need to make your variables into factors and specify the levels.

> x <- c(1,3,4,5)
> table(x)
x
1 3 4 5
1 1 1 1
> factor(x)
[1] 1 3 4 5
Levels: 1 3 4 5
> table(factor(x))
1 3 4 5
1 1 1 1
> table(factor(x, levels=1:5))
1 2 3 4 5
1 0 1 1 1
>

Rich
On Tue, Mar 8, 2011 at 3:22 PM, Shi, Tao <shidaxia@yahoo.com> wrote:

> Hi list,
>
> Is there already a function somewhere to output the confusion matrix from
> two
> input vectors?  "table" always automatically delete rows or columns with
> all
> 0's.  For example, I would like the columns for "10" and "30" added back.
>
> Thanks!
>
> ...Tao
>
>
>
>      20 40 50 60 70 80 90 100
>  10   0  0  1  0  0  0  1   0
>  20   1  2  0  4  0  0  0   1
>  30   0  0  0  0  0  0  1   1
>  40   0  0  1  1  2  0  0   0
>  50   0  1  0  0  0  1  0   0
>  60   0  0  0  0  0  0  1   1
>  70   0  0  1  1  1  1  1   1
>  80   0  1  0  0  0  0  0   1
>  90   0  0  0  0  0  0  0   3
>  100  0  0  0  0  1  0  0   3
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>

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