R help - Feb 2021 - 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]]

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]]
> 
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