Re: [R] median of binned values

From: Martin Tomko <martin.tomko_at_geo.uzh.ch>
Date: Wed, 19 Dec 2007 11:17:48 +0100

Thank you, Chuck,
would you mind commenting a bit on the code, it is not all clear... HOw would you go to retrieve only the numeric value (not the category name)? I am just starting with R, and the functionality of replicate and levels is not quite clear. I tried the documentation, but am not any wiser. What if I had a vector v <- vector(c(1,10,100,1000,10000)) and wanted to perform it on that?

Thanks a lot
Martin

Chuck Cleland wrote:

> Martin Tomko wrote:

>> Dear list,
>> I have a vector (array, table row, whatever is best) of frequency values
>> for categories (or bins), and I need to find the median category.
>> Trivial to do by hand, but I was wondering if there is a means to do it
>> in R in an elegant way.
>>
>> The obvious medioan(vector) returns the median frequency for the binns,
>> and that is not what I want. i.e,:
>> freq
>> cat1 1
>> cat2 10
>> cat3 100
>> cat4 1000
>> cat5 10000
>>
>> I want it to return cat5, instead of cat3.
> 
> df <- data.frame(binname = as.factor(paste("cat", 1:5, sep="")),
>                  freq = c(1,10,100,1000,10000))
> 
> df
>   binname  freq
> 1    cat1     1
> 2    cat2    10
> 3    cat3   100
> 4    cat4  1000
> 5    cat5 10000
> 
> with(df, levels(binname)[median(rep(as.numeric(binname), freq))])
> [1] "cat5"
> 

>> Thanks a lot
>> Martin
>>
>> ______________________________________________
>> R-help_at_r-project.org mailing list
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>
-- 
Martin Tomko
Postdoctoral Research Assistant

Geographic Information Systems Division
Department of Geography
University of Zurich - Irchel
Winterthurerstr. 190
CH-8057 Zurich, Switzerland

email: 	martin.tomko_at_geo.uzh.ch
site:	http://www.geo.uzh.ch/~mtomko
mob: 	+41-788 629 558
tel: 	+41-44-6355256
fax: 	+41-44-6356848

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Received on Wed 19 Dec 2007 - 10:21:02 GMT

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