Re: sorting and ordering bars in a ggplot2 bar chart.

[Ben Bond-Lamberty]

I agree with the stackoverflow responders that the question isn't
completely clear. Nonetheless something like this may help...it
produces an order bar graph by your domain and category variables:

# 1. Summarize the data
library(plyr)
d2 <- ddply(ex1.dta,.(category,domain),summarise,grouping=sum(grouping))

# 2. Reorder and create a new x axis label
d3 <- d2[order(d2$category,d2$grouping),] # reorder
d3$catdom <- paste(d3$category,d3$domain) # make a new plotting var
d3$catdom <- factor(d3$catdom,levels=d3$catdom)

# 3. Plot
qplot(catdom,grouping,fill=category,data=d3,geom="bar",stat="identity")+theme(axis.text.x
= element_text(angle = 90))

Ben


On Mon, Dec 10, 2012 at 7:58 AM, eastafri <geor...@gmail.com> wrote:
> I had posted this question on stackoverflow though i did not get a
> satisfactory answer on how to order the bars using code. Maybe someone has
> an idea?
> http://stackoverflow.com/questions/12449924/grouping-bars-in-a-ggplot2
>
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[eastafri]

Thanks Ben. what I wanted are the stacked bars like the ones from the question. Sorry if the initial question was not as clear. But to clarify, I wanted a stacked bar chart with the bars along the X-axis ordered  via some other variable and in an descending manner. I thought it should be straighforward to do this with ggplot2, but it seems to be difficult. 

[Dennis Murphy]

Hi:

On Wed, Dec 12, 2012 at 12:00 AM, eastafri <geor...@gmail.com> wrote:
> Thanks Ben. what I wanted are the stacked bars like the ones from the
> question. Sorry if the initial question was not as clear. But to clarify, I
> wanted a stacked bar chart with the bars along the X-axis ordered via some
> other variable and in an descending manner. I thought it should be
> straighforward to do this with ggplot2, but it seems to be difficult.

See the reorder() function to arrange the levels of a factor according
to some function of the values of another variable. Here's a simple
reproducible example to illustrate the point:

DF <- data.frame(expand.grid(a = c("I", "II", "III"), b = LETTERS[1:3]),
n = rpois(9, 60))
require(ggplot2)

# ascending order of cumulative bar height:
ggplot(DF, aes(x = reorder(a, n, sum), y = n, fill = b)) +
geom_bar(stat = "identity", position = "stack")

# descending order:
ggplot(DF, aes(x = reorder(a, -n, sum), y = n, fill = b)) +
geom_bar(stat = "identity", position = "stack")

Dennis

[George Githinji]

Thanks Dennis,
I am a little confused here. :)
Can you do that with the example I have given and express the y axis
as a proportion of the total.
In my example(http://stackoverflow.com/questions/12449924/grouping-bars-in-a-ggplot2)
all the variables are categorical variables.

Furthermore I get this with your example, when I attempt to use
proportions on the y- axis

ggplot(DF, aes(x = reorder(a, -n, sum), y = n, fill = b)) +

+ geom_bar(position="fill")

Mapping a variable to y and also using stat="bin".
With stat="bin", it will attempt to set the y value to the count of
cases in each group.
This can result in unexpected behavior and will not be allowed in a
future version of ggplot2.
If you want y to represent counts of cases, use stat="bin" and don't
map a variable to y.
If you want y to represent values in the data, use stat="identity".
See ?geom_bar for examples. (Deprecated; last used in version 0.9.2)

On Wed, Dec 12, 2012 at 11:28 AM, Dennis Murphy <djm...@gmail.com> wrote:
> ggplot(DF, aes(x = reorder(a, -n, sum), y = n, fill = b)) +
> geom_bar(stat = "identity", position = "stack")

--
---------------
Sincerely
George
Skype: george_g2
Blog: http://www.biorelated.com/
Twitter: http://twitter.com/#!/george_l

[Ben Bond-Lamberty]

Well, did you try the example code I sent? It orders X axis bars and
should be straightforward to modify for your needs.

Kind regards
Ben

[eastafri]

Yes i tried it with 

ggplot(d3,aes(domain,fill=category)) + geom_bar(position="fill") +opts(

+     axis.text.x=theme_text(angle=-90,hjust=0),

+     axis.line = theme_segment(colour = "black"),

+     panel.grid.major = theme_blank(),

+     panel.grid.minor = theme_blank(),

+     panel.border = theme_blank()) +

+     geom_vline(xintercept = 0)

That is more close to what i needed but it does not work and order the bars in the desired order.

[Ben Bond-Lamberty]

I would suggest posting a simplified, reproducible example: a toy data
set, and a clear description of exactly what you want to do. Both
Dennis and I are confused, I think.

Ben

[Joran]

I explained to you in my comments at StackOverflow how to order the bars along the x axis.