[R] overlaying frequency histograms or density plots in R

[Bogdan Tanasa]

Dear Rui, and Petr,

many many thanks for your time and advice ! 'm still exploring the R code
that you have suggested !

On Thu, Feb 25, 2021 at 2:59 AM Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Hello,
>
> First of all, I believe you want argument fill, not colour. In ggplot2
> colour is about the border and fill about the interior.
>
> As for the question,
>
> 1. Create a basic plot with the common aesthetics.
>
>
> library(ggplot2)
>
> pp_ALL <- iris[c(1, 5)]
> names(pp_ALL) <- c("VALUE", "EXP")
>
> p <- ggplot(data = pp_ALL, mapping = aes(x = VALUE, fill = EXP))
>
>
>
> 2. geom_density should use alpha transparency, since the densities
> overlap. colour = NA removes the densities black border.
>
>
> p + geom_density(alpha = 0.5, colour = NA)
>
>
> 3. y = ..density.. plots relative frequencies histograms, for the
> default absolute frequencies or counts, comment the mapping out.
>
> position = position_dodge() allows for extra goodies, such as to change
> the space between bars, their width or to keep empty spaces when some
> factor levels are missing (preserve = "single").
>
> For the test data, with 50 elements per factor level, use a much smaller
> number of bins.
>
> Package scales has functions to display labels in percent format, there
> is no need to multiply by 100.
>
>
> p + geom_histogram(
>    mapping = aes(y = ..density..),
>    position = position_dodge(),
>    bins = 10)
>
> p + geom_histogram(
>    mapping = aes(y = ..density..),
>    position = position_dodge(),
>    bins = 10) +
>    scale_y_continuous(labels = scales::label_percent())
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> Às 07:43 de 25/02/21, Bogdan Tanasa escreveu:
> > Thanks a lot Petr !
> >
> > shall i uses "dodge" also for the RELATIVE FREQUENCY HISTOGRAMS :
> >
> > p <- ggplot(iris, aes(x=Sepal.Length, y=..count../sum(..count..)*100,
> > colour=Species))
> > p+geom_histogram(position="dodge")
> >
> > or is there any other way to display the RELATIVE FREQUENCY HISTOGRAMS ?
> >
> > thanks again !
> >
> > On Wed, Feb 24, 2021 at 11:00 PM PIKAL Petr <petr.pikal using precheza.cz>
> wrote:
> >
> >> Hi
> >>
> >> You should use position dodge.
> >>
> >> p <- ggplot(iris, aes(x=Sepal.Length, colour=Species))
> >> p+geom_density()
> >> p <- ggplot(iris, aes(x=Sepal.Length, y=..density.., colour=Species))
> >> p+geom_histogram(position="dodge")
> >>
> >> Cheers
> >> Petr
> >>> -----Original Message-----
> >>> From: R-help <r-help-bounces using r-project.org> On Behalf Of Bogdan Tanasa
> >>> Sent: Wednesday, February 24, 2021 11:07 PM
> >>> To: r-help <r-help using r-project.org>
> >>> Subject: [R] overlaying frequency histograms or density plots in R
> >>>
> >>> Dear all, we do have a dataframe with a FACTOR called EXP that has 3
> >> LEVELS ;
> >>>
> >>>   head(pp_ALL)
> >>>      VALUE  EXP
> >>> 1 1639742 DMSO
> >>> 2 1636822 DMSO
> >>> 3 1634202 DMSO
> >>>
> >>> shall i aim to overlay the relative frequency histograms, or the
> density
> >>> histograms for the FACTOR LEVELS,
> >>>
> >>> please would you let me know why the following 2 pieces of R code show
> >>> very different results :
> >>>
> >>> ggplot(pp_ALL, aes(x=VALUE, colour=EXP)) + geom_density()
> >>>
> >>> versus
> >>>
> >>> ggplot(data=pp_ALL) +
> >>>         geom_histogram(mapping=aes(x=VALUE, y=..density.., colour=EXP),
> >>>   bins=1000)
> >>>
> >>> thanks,
> >>>
> >>> bogdan
> >>>
> >>> ps : perhaps i shall email to the folks on ggplot2 mailing list too ...
> >>>
> >>>        [[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.
> >>
> >
> >       [[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.
> >
>

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