[R] how to remove factors from whole dataframe?

[Avi Gross]

Glad we have solutions BUT I note that the more abstract question is how to convert any columns that are factors to their base type and that may well NOT be character. They can be integers or doubles or complex or Boolean and maybe even raw. 

So undoing factorization may require using something like typeof() to get the base type and then depending on what final type you have, you may have to do things like as.integer(as.character(the_factor)) to get it as an integer and for a logical, as.logical(factor(c(TRUE, TRUE, FALSE, TRUE, FALSE))) and so on.

This seems like a fairly basic need so I wonder if anyone has already done it. I can see a fairly straightforward way to build a string and use eval and I suspect others might use something else like do.call() and yet others use multiple if statements or a case_when or something




-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Luigi Marongiu
Sent: Sunday, September 19, 2021 4:43 PM
To: Rui Barradas <ruipbarradas using sapo.pt>
Cc: r-help <r-help using r-project.org>
Subject: Re: [R] how to remove factors from whole dataframe?

Awesome, thanks!

On Sun, Sep 19, 2021 at 4:22 PM Rui Barradas <ruipbarradas using sapo.pt> wrote:
>
> Hello,
>
> Using Jim's lapply(., is.factor) but simplified, you could do
>
>
> df1 <- df
> i <- sapply(df1, is.factor)
> df1[i] <- lapply(df1[i], as.character)
>
>
> a one-liner modifying df, not df1 is
>
>
> df[sapply(df, is.factor)] <- lapply(df[sapply(df, is.factor)], 
> as.character)
>
>
> Hope this helps,
>
> Rui Barradas
>
> Às 11:03 de 19/09/21, Luigi Marongiu escreveu:
> > Thank you Jim, but I obtain:
> > ```
> >> str(df)
> > 'data.frame': 5 obs. of  3 variables:
> >   $ region : Factor w/ 5 levels "A","B","C","D",..: 1 2 3 4 5
> >   $ sales  : num  13 16 22 27 34
> >   $ country: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5
> >> df1<-df[,!unlist(lapply(df,is.factor))]
> >> str(df1)
> >   num [1:5] 13 16 22 27 34
> >> df1
> > [1] 13 16 22 27 34
> > ```
> > I was expecting
> > ```
> > str(df)
> > 'data.frame': 5 obs. of  3 variables:
> >   $ region : char "A","B","C","D",..: 1 2 3 4 5
> >   $ sales  : num  13 16 22 27 34
> >   $ country: char "a","b","c","d",..: 1 2 3 4 5 ```
> >
> > On Sun, Sep 19, 2021 at 11:37 AM Jim Lemon <drjimlemon using gmail.com> wrote:
> >>
> >> Hi Luigi,
> >> It's easy:
> >>
> >> df1<-df[,!unlist(lapply(df,is.factor))]
> >>
> >> _except_ when there is only one column left, as in your example. In 
> >> that case, you will have to coerce the resulting vector back into a 
> >> one column data frame.
> >>
> >> Jim
> >>
> >> On Sun, Sep 19, 2021 at 6:18 PM Luigi Marongiu <marongiu.luigi using gmail.com> wrote:
> >>>
> >>> Hello,
> >>> I woul dlike to remove factors from all the columns of a dataframe.
> >>> I can do it n a column at the time with ```
> >>>
> >>> df <- data.frame(region=factor(c('A', 'B', 'C', 'D', 'E')),
> >>>                   sales = c(13, 16, 22, 27, 34), 
> >>> country=factor(c('a', 'b', 'c', 'd', 'e')))
> >>>
> >>> new_df$region <- droplevels(new_df$region) ```
> >>>
> >>> What is the syntax to remove all factors at once (from all columns)?
> >>> For this does not work:
> >>> ```
> >>>> str(df)
> >>> 'data.frame': 5 obs. of  3 variables:
> >>>   $ region : Factor w/ 5 levels "A","B","C","D",..: 1 2 3 4 5
> >>>   $ sales  : num  13 16 22 27 34
> >>>   $ country: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5
> >>>> df = droplevels(df)
> >>>> str(df)
> >>> 'data.frame': 5 obs. of  3 variables:
> >>>   $ region : Factor w/ 5 levels "A","B","C","D",..: 1 2 3 4 5
> >>>   $ sales  : num  13 16 22 27 34
> >>>   $ country: Factor w/ 5 levels "a","b","c","d",..: 1 2 3 4 5 ``` 
> >>> Thank you
> >>>
> >>> ______________________________________________
> >>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see 
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> >>> PLEASE do read the posting guide 
> >>> http://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >
> >
> >



--
Best regards,
Luigi

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and provide commented, minimal, self-contained, reproducible code.