[R] sorting a data.frame (df) by a vector (which is not contained in the df) - unexpected behaviour of match and factor

[Berend Hasselman]

drflxms wrote
> 
> Jeff,
> 
> thanks a lot for your quick reply and the hint!
> 
> Meanwhile I found a solution that works - at least for my case ;)
> The code to get the job done is
> 
> df[order(match(df$level,desiredOrder)),]
> 
> So we seem in need of one order statement more. I found this solution
> doing it stepwise:
> 
> ## sorting the levels of the level column in the data.frame
> df$level <- factor(df$level,levels=desiredOrder)
> ## sorting the data frame by the newly sorted level column
> df[order(df$level),]
> 
> Maybe this solution is of a help for someone else as well?
> 
> But honestly I still do not exactly understand why
> df[match(df$level,desiredOrder),] doesn't work...
> 

Read carefully

?match

and  then do

match(df$level,desiredOrder)
match(desiredOrder,df$level)

and look carefully at the results. Then it should be clear.

Berend



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