[R] plot factors with dots in R

[Luigi Marongiu]

Thank you, better than before...

On Thu, Aug 27, 2020 at 2:37 PM PIKAL Petr <petr.pikal using precheza.cz> wrote:
>
> Hi.
> It is probably somewhere in docs, but factors are actually numerics vith
> labels.
>
> So with your original data frame
>
> df$x <- factor(df$x)
> plot(as.numeric(df$x), df$y)
>
> gives you points. You need to set labels to x axis though.
>
> Cheers
> Petr
>
> > -----Original Message-----
> > From: R-help <r-help-bounces using r-project.org> On Behalf Of Luigi Marongiu
> > Sent: Thursday, August 27, 2020 2:16 PM
> > To: r-help <r-help using r-project.org>
> > Subject: [R] plot factors with dots in R
> >
> > Hello,
> > I have a dataframe as follows:
> > ```
> > x = c("0 pmol", "10 pmol", "100 pmol", "1000 pmol")
> > y = c(0.9306, 1.8906, 2.2396, 2.7917)
> > df = data.frame(x, y)
> >
> > > str(df)
> > 'data.frame': 4 obs. of  2 variables:
> >  $ x: chr  "0 pmol" "10 pmol" "100 pmol" "1000 pmol"
> >  $ y: num  0.931 1.891 2.24 2.792
> > ```
> > I would like to visualize the data with the classic dots (pch=16) but:
> > ```
> > > plot(df$y ~ df$x)
> > Error in plot.window(...) : need finite 'xlim' values
> > In addition: Warning messages:
> > 1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
> > 2: In min(x) : no non-missing arguments to min; returning Inf
> > 3: In max(x) : no non-missing arguments to max; returning -Inf
> > ```
> > which is right because x is not numeric, so I took the factor:
> > ```
> > plot(df$y ~ factor(df$x)) # gives bars instead of dots
> > plot(df$y ~ factor(df$x), pch = 16) # this also
> > ```
> > I tried to convert directly the dataframe:
> > ```
> > df$x = lapply(df$x, factor)
> > > str(df)
> > 'data.frame': 4 obs. of  2 variables:
> >  $ x:List of 4
> >   ..$ : Factor w/ 1 level "0 pmol": 1
> >   ..$ : Factor w/ 1 level "10 pmol": 1
> >   ..$ : Factor w/ 1 level "100 pmol": 1
> >   ..$ : Factor w/ 1 level "1000 pmol": 1
> >  $ y: num  0.931 1.891 2.24 2.792
> >
> > > plot(r$y ~ r$x, pch = 16)
> > Error in plot.window(...) : need finite 'xlim' values
> > In addition: Warning messages:
> > 1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
> > 2: In min(x) : no non-missing arguments to min; returning Inf
> > 3: In max(x) : no non-missing arguments to max; returning -Inf
> > ```
> > If I try to pass the number of levels:
> > ```
> > plot(df$y ~ factor(df$x, 1:4), pch = 16) # this draw a boxplot with
> > all data on level 1
> >
> > > df$x = lapply(df$x, factor(1:4))
> > Error in match.fun(FUN) :
> >   'factor(1:4)' is not a function, character or symbol
> > ```
> >
> > Since the transformation has given only one level (1), my questions are:
> > How do I tell R to use a dot instead of a line?
> > What is the correct way of setting factors?
> >
> >
> > --
> > Best regards,
> > Luigi
> >
> > ______________________________________________
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> > and provide commented, minimal, self-contained, reproducible code.



-- 
Best regards,
Luigi