R help - Sep 2021 - how to remove factors from whole dataframe?

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 at
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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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 at 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 at
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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > 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