Re: st: Stacked bar graph with twoway__histogram_gen

[Nick Cox <njcoxstata@gmail.com>]

I wouldn't do this. You want to subdivide a histogram according to two
categories.

My recipe for such cases is

1. Lay down a histogram for everything.

2. Lay down a histogram for one category on top.

Then the difference is just the histogram for the other category, stacked.

Here is some example code:

 sysuse auto

twoway histogram mpg , width(2) start(10) barw(1.98) freq
bfcolor(red*0.6) blcolor(gs12)
|| histogram mpg if foreign , width(2) barw(1.98) start(10) freq
blcolor(gs12) bfcolor(blue*0.6)
legend(order(1 "Domestic" 2 "Foreign") col(1) ring(0) pos(1))

See also

Cox, N.J. 2009.
Stata tip 78: Going gray gracefully: Highlighting subsets and
downplaying substrates
The Stata Journal 9(3): 499-503

On Wed, Mar 7, 2012 at 6:28 PM, Stefano Lombardi
<lombardi_stefano@fastwebnet.it> wrote:

> I have a problem in plotting a stacked bar graph. I have read some
> documentation on the Internet and I am really close to obtain what I need,
> but still I cannot manage to solve one issue (I haven't found any similar
> problem on the Statalist archive..)
>
> In practice, I have one duration variable in months (overall survival, "os")
> which as usual can be either censored or uncensored (the failure dummy is
> "status_os"; 1 = os is uncensored). I need to create a stacked bar graph
> with different colors for censored and uncensored data (blue and red,
> respectively). My code is the following:
>
>    use "epd0", clear
>    twoway__histogram_gen os if status_os==0, gen(freq_1 x, replace) ///
>    freq start(0) width(5)
>    drop if missing(x)
>    keep freq_1 x
>    save f1, replace
>
>    use "epd0", clear
>    twoway__histogram_gen os if status_os==1, gen(freq_2 x, replace) ///
>    freq start(0) width(5)
>    drop if missing(x)
>    keep freq_2 x os
>
>    merge 1:1     x using f1
>    mvencode freq_1 freq_2, mv(. = 0)
>
>    egen freq = rowtotal(freq_1 freq_2)
>
>    twoway ///
>    (bar freq_1 x, barw(5) bcolor(red)) ///
>    rbar freq_2 freq x, barw(5) bcolor(blue) ///
>    legend(order(1 "Uncensored" 2 "Censored")) ///
>    xtitle("`: var label os'") ytitle(Frequency)
>
> Everything looks perfect but for one thing. In one bin there is a blank gap
> between the lower red bar (which counts for two observations) and the upper
> blue bar (other two observations).
> Actually -- also by checking the previously generated frequencies --  the
> lower bar should correspond to three observations, hence the blank gap
> should be red.
>
> Can you suggest any solution? It may be a coincidence, but that bin is the
> only one where there should be plotted more uncensored (red) data than
> censored (blue) ones.

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/