overlaying frequency histograms or density plots in R

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 at r-project.org> On Behalf Of Bogdan Tanasa
Sent: Wednesday, February 24, 2021 11:07 PM
To: r-help <r-help at 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]]