[R] #Keeping row names when using as.data.frame.matrix

David Winsemius dwinsemius at comcast.net
Fri May 17 21:05:33 CEST 2013


On May 17, 2013, at 9:46 AM, Tim wrote:

> #question I have the following data set:
> 
> Date<-c("9/7/2010","9/7/2010","9/7/2010","9/7/2010","9/7/2010","9/7/2010","9/8/2010")
> 
> EstimatedQuantity<-c(3535,2772,3279,3411,3484,3274,3305)
> 
> ScowNo<-c("4001","3002","4002","BR 8","4002","BR 8","4001")
> 
> dataset<- data.frame(EstimatedQuantity,Date,ScowNo)
> 
> #I'm trying to convert the data set into a contingency table and then back
> into a regular data frame:
> 
> 
> xtabdata<-as.data.frame.matrix(xtabs(EstimatedQuantity~Date+ScowNo,data=dataset),
>         row.names=(dataset$Date),optional=F)
> 
> #I'm trying to keep the row names (in xtabsdata) as the dates.
> #But the row names keep coming up as integers.
> #How can I preserve the row names as dates when
> #the table is converted back to a data frame?

It's a factor-problem (see the FAQ …. read all of section 7, i'm too lazy to look it up again.):

xtabdata<-as.data.frame.matrix(xtabs(EstimatedQuantity~Date+ScowNo,data=dataset),
          row.names=sort( unique( as.character(dataset$Date))), optional=F)

> 
> 
> 
> 
> --
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> 
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David Winsemius
Alameda, CA, USA



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