[R] Apply as.factor (or as.numeric etc) to multiple columns

[baptiste auguie]

Wacek helped me out on a similar topic a while back,

ize =
function (d, columns = names(d), izer = as.factor)
{
    d[columns] = lapply(d[columns], izer)
    d
}
d = data.frame(x=1:10, y=1:10, z =1:10)

str( ize(d, 'y') ) # y is now a factor
str( ize(d, 1:2, `cumsum`) ) # x and y are affected

etc.

HTH,

baptiste



Mark Na wrote:
> Hi R-helpers,
>
> I have a dataframe with 60columns and I would like to convert several
> columns to factor, others to numeric, and yet others to dates. Rather
> than having 60 lines like this:
>
> data$Var1<-as.factor(data$Var1)
>
> I wonder if it's possible to write one line of code (per data type,
> e.g. factor) that would apply a function (e.g., as.factor) to several
> (non-contiguous) columns. So, I could then use 3 or 4 lines of code
> (for 3 or 4 data types) instead of 60.
>
> I have tried writing an apply function, but it failed.
>
> Thanks for any help you might be able to provide.
>
> Mark Na
>
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>
>   


-- 
_____________________________

Baptiste Auguié

School of Physics
University of Exeter
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http://newton.ex.ac.uk/research/emag