Friedrich Huebler suggested a problem
> How can I add the contents of a variable to a graph title? I work
> with data like this:
>
> country year total male female
> Albania 1999 20 15 25
> Algeria 2000 10 15 5
> Angola 2000 30 35 25
>
> The following commands produce bar graphs for individual countries.
>
> levels country, local(countries)
> foreach c of local countries {
> graph bar total male female if country=="`c'", title("`c'")
> }
>
> The title contains the country name and I would like to add
> the year,
> as in "Albania 1999." This looks like a trivial problem but I cannot
> find a solution.
For those following, let me stress that this is all (up-to-date)
Stata 8.
The following solutions have been suggested:
(1) Lee Sieswerda
=================
I don't know if this is the most efficient way to accomplish your
task, but
it works:
levels country, local(countries)
levels year, local(year)
foreach c of local countries {
foreach y of local year {
capture graph bar total male female if country=="`c'" &
year==`y', title("`c' `y'")
}
}
You need the -capture- before -graph bar-, otherwise your do-file will
end
as soon as the -foreach- loops generate a country/year combination
that
doesn't exist.
(2) Kit Baum
============
Assuming you only have one year per country, this is a bit less work
than checking every possible year/country combination:
levels country, local(countries)
g n = _n
foreach c of local countries {
summ n if country=="`c'",meanonly
local y = year[r(min)]
graph bar total male female if country=="`c'", title("`c' `y'")
}
(3) Michael Blasnik
===================
Even less work is:
gen countryyear=country+" "+string(year)
levels countryyear, local(countries)
foreach c of local countries {
graph bar total male female if countryyear=="`c'", title("`c'")
}
All these solutions show key Stata tricks, as follows:
(1) A double loop and -capture- (Lee). This is crude,
but often practical: you make Stata do the work of catching
the pairs which don't apply.
(2) Look-up technique (Kit). I know the value of one
variable in an observations, but not another. How
do I find it? The
technique illustrated by Kit has many applications.
(3) A new composite variable (Michael). Sometimes
a slightly different data representation does
the trick.
Here is yet another solution.
(4)
Friedrich wants here the often-maligned loop over observations,
so we are not obliged to use -levels-:
forval i = 1 / `=_N' {
graph bar country in `i', ti(`=country[`i']' `=year[`i']')
}
The trick is the construct
`=whatever'
which evaluates whatever and inserts its value in the same
place.
Having said that, for whatever is Friedrich's real problem
there could also be value in a plot of several countries'
values. For that, in addition to -graph dot-, -pairplot-
on SSC offers various possibilities.
Nick
[email protected]
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
