[R] Remove all factor levels from an R dataframe

[Eric Berger]

Hi John,
I was thinking that you created df1 in a way that set the 'year'
column as a factor when this is not what you wanted to do.
The data.frame() function takes an argument stringsAsFactors which
controls this behavior.
For R versions 3.6.3 or earlier, the default setting is
stringsAsFactors=TRUE, which means that string columns automatically
become factors.
You have to specify stringsAsFactors=FALSE to avoid this. (In R 4.0.x
the default was changed to FALSE.)

Example:
df1 <- data.frame( a=letters[1:10], stringsAsFactors=FALSE )

HTH,
Eric

On Tue, Nov 10, 2020 at 11:16 AM Jim Lemon <drjimlemon using gmail.com> wrote:
>
> Sure John,
>
> df1<-df1[order(as.character(df1$year),decreasing=TRUE),]
>
> Jim
>
> On Tue, Nov 10, 2020 at 8:05 PM John <miaojpm using gmail.com> wrote:
>
> > Thanks Jim. Can we do descending order?
> >
> > Jim Lemon <drjimlemon using gmail.com> 於 2020年11月10日 週二 下午4:56寫道：
> >
> >> Hi John,
> >>
> >> df1<-sapply(df1,as.character)
> >>
> >> Should do what you ask. The error message probably means that you should
> >> do this:
> >>
> >> df1<-df1[order(as.character(df1$year)),]
> >>
> >> as "year" is the name of the first column in df1, not a separate object.
> >>
> >> Jim
> >>
> >> On Tue, Nov 10, 2020 at 6:57 PM John <miaojpm using gmail.com> wrote:
> >>
> >>> Hi,
> >>>
> >>>    I would like to sort the following simple dataframe by "year"
> >>> (characters), but the factor structure prevents me from doing so. How
> >>> can I
> >>> remove the factor structure? Thanks!
> >>>
> >>> > df1
> >>>   year                  country
> >>> 4 2007             Asia; survey
> >>> 5 2010 8 countries in E/SE Asia
> >>> 6 2015                    Ghana
> >>> 7
> >>> 8 2000                      US?
> >>> > str(df1)
> >>> 'data.frame': 5 obs. of  2 variables:
> >>>  $ year   : Factor w/ 9 levels "2017","2016",..: 4 5 3 6 7
> >>>  $ country: Factor w/ 9 levels "Euro Area\\newline Testing the MP
> >>> performance of the Euro Area",..: 4 5 6 7 8
> >>> > df1[order(-year), ]
> >>> Error in order(-year) : object 'year' not found
> >>>
> >>>         [[alternative HTML version deleted]]
> >>>
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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.
> >>>
> >>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using 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.