[R] ipf function in R

[Charles C. Berry]

On Wed, 5 Mar 2008, Chandra Shah wrote:

> Hi
> I have a 3 x 2 contingency table:
> 10 20
> 30 40
> 50 60
> I want to update the frequencies to new marginal totals:
> 100 130
> 40 80 110
> I want to use  the ipf (iterative proportional fitting) function which
> is apparently in the cat package.
> Can somebody please advice me how to input this data and invoke ipf in R
> to obtain an updated contingency table?

I'd use loglin()

 	newtab <-
 		loglin(	rowmarg%o%colmarg/sum(colmarg),
 		margin=list(1,2),
 		start=tab, fit=TRUE )$fit


with rowmarg and colmarg set to your updated marginals.

As for inputting the data, if this is all you have, type it in at the 
command line. See

 	?matrix
 	?c

and note this:

> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

HTH,

Chuck


> Thanks.
> By the way I am quite new to R.
>
> -- 
>
>
> Dr Chandra Shah
> Senior Research Fellow
> Monash University-ACER Centre for the Economics of Education and Training
> Faculty of Education, Building 6,
> Monash University
> Victoria
> Australia 3800
> Tel. +61 3 9905 2787
> Fax +61 3 9905 9184
>
> www.education.monash.edu.au/centres/ceet
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901