Re: [R] Elegant way to transform dataframe?

From: ONKELINX, Thierry <Thierry.ONKELINX_at_inbo.be>
Date: Thu, 20 Nov 2008 10:00:21 +0100

Dear Barry,

Have a look at the function cast() in the reshape package. That should be able to do what you need.

HTH, Thierry




ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics, methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx_at_inbo.be
www.inbo.be

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~ Sir Ronald Aylmer Fisher

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~ Roger Brinner

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~ John Tukey

-----Oorspronkelijk bericht-----
Van: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org] Namens Barry Rountree
Verzonden: donderdag 20 november 2008 8:39 Aan: r-help_at_r-project.org
Onderwerp: [R] Elegant way to transform dataframe?

Hello,

I have a dataframe with columns like:

  parameter1 parameter2 metricname value

and I'd like to transform it into a dataframe with columns:

  parameter1 parameter2 metric1 metric2 metric3

where the values for each metric would be in the appropriate column. There are often multiple values for a given (parameter1, parameter2, metricname) triple. In this case, I want to use the minimum value.

A constant number of metrics is associated with each possible combination of parameters.

I've cobbled together code that performs this using nested loops and far too many variables. The number of metrics has now gone up by an order of magnitude and I'm looking for a more elegant way of doing this.

If anyone has a short bit of code that can deal with this, I'd really appreciate having a look.

Thanks much,

Barry



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