[R] A printing "macro"

[Prof Brian Ripley]

ddisp <- function(dvar) {
     yn <- substitute(dvar)
     csqt <- eval.parent(substitute(chisq.test(G,dvar), list(dvar=yn)))
     ....
}

There are other ways, such as forming the cross-classification table, 
setting its dimnames and passing that to chisq.test.

On Mon, 13 Nov 2006, Murray Jorgensen wrote:

> I am exploring the result of clustering a large multivariate data set
> into a number of groups, represented, say, by a factor G.
>
> I wrote a function to see how categorical variables vary between groups:
>
> >  ddisp <- function(dvar) {
> +  csqt <- chisq.test(G,dvar)
> +  print(csqt$statistic)
> +  print(csqt$observed)
> +  print(round(csqt$expected))
> +  round(csqt$residuals)
> +  }
> >
> >  x <- ceiling(4*runif(100))
> >  G <- gl(4,1,100)
> >  ddisp(x)
> X-squared
>  6.235645
>    dvar
> G    1  2  3  4
>   1 10  5  5  5
>   2  6  9  5  5
>   3  8  6  5  6
>   4  7  4  4 10
>    dvar
> G   1 2 3 4
>   1 8 6 5 6
>   2 8 6 5 6
>   3 8 6 5 6
>   4 8 6 5 6
>    dvar
> G    1  2  3  4
>   1  1  0  0 -1
>   2 -1  1  0 -1
>   3  0  0  0  0
>   4  0 -1  0  1
> Warning message:
> Chi-squared approximation may be incorrect in: chisq.test(G, dvar)
>
> As I need to apply this function to a large number of variables x it
> would be helpful if the function printed "x" rather than the formal
> argument "dvar". I have a vague idea that things like deparse() and
> substitute() will come into the solution but I have not yet come up with
> the right incantation. Any help appreciated!
>
> Murray Jorgensen
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595