Re: [R] replace matrix values with names from a dataframe

From: Dimitris Rizopoulos <dimitris.rizopoulos_at_med.kuleuven.be>
Date: Fri 29 Jul 2005 - 00:06:42 EST

maybe something like this could be helpful

city.name <- c("munich", "paris", "tokio", "london", "boston") X <- cbind(c(2, 5, 5), c(4, 1, 3))
####
matrix(city.name[X], ncol = 2)

I hope it helps.

Best,
Dimitris



Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium

Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm



> Hi,
>
> I am looking for a way to replace matrix values with names from a
> dataframe.
>
> Let me do this by example: I have a dataframe:
>
>>data
> city.name
> 1 munich
> 2 paris
> 3 tokio
> 4 london
> 5 boston
>
> each city name corresponds to only one index number (there is only
> one
> observation for each city). After doing some matching I end up with
> a matrix
> that looks something like this:
>
>> X
> [,1] [,2]
> [1,] 2 4
> [2,] 5 1
> [3,] 5 3
> [4,] 12 217
> [5,] 16 13
>
> Here the numbers in the matrix are the index numbers from my
> original dataset,
> each row is a matched pair (so e.g. the first row tells me that obs.
> number 2
> (i.e. Paris) was matched to obs number 4 (i.e. London)).
>
> Now I am looking for a quick way to transform the index numbers back
> to city
> names, so that at the end I have a matrix that looks something like
> this:
>
>> X.transformed
> [,1] [,2]
> [1,] paris london
> [2,] boston munich
> [3,] boston tokio
> [4,] 12 217
> [5,] 16 13
>
> etc. So instead of the index number, the matrix should contain the
> names that
> corresponds to it. In my real data, I have many many names and
> replacing each
> value by hand would take too long. Any help is highly appreciated.
>
> Thank you.
>
> Regards,
> Jens
>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jul 29 00:16:42 2005

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