[R] concatenating factor from list

[Gabor Grothendieck]

Is this ok or is it what you are trying to avoid:

  factor(unlist(lapply(cutYield, as.character)))


On 3/15/06, Sebastian Luque <spluque at gmail.com> wrote:
> Hi,
>
> I've run into a ridiculous problem I can't find any solutions for in the
> archives or help pages:
>
> data(barley)
> cutYield <- with(barley, by(yield, variety, cut, breaks = c(0, 30, 60, 90)))
>
> As in this example, I'm using 'by' to return a factor for each level of
> another factor.  The problem is that 'by' returns a list of the factors,
> and I need all these factors concatenated.  No problem, I said:
>
> unlist(cutYield)
>
> which returns an 'integer' class object, so it's no longer a factor.  The
> same happens with:
>
> do.call(c, cutYield)
>
> I could recreate the factor from the integer level codes returned above,
> but this is not good because this means redoing the job already done by
> the function called in 'by', making the code more prone to errors.
>
> Thanks in advance for any pointers,
>
> --
> Sebastian
>
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