Programs problem set question

[matthew-white]

Here's a potential problem set question for a module on writing programs. I often use it when training others.

label list lists the contents of a value label:

sysuse auto, clear
label list origin

However, label list does not accept variable names as arguments: it requires value label names. This means that listing the contents of a variable's value label takes two steps: one to determine the label name and another to list that label. For instance, label list results in an error if specified the name of the value-labeled foreign variable in the auto dataset:

sysuse auto, clear

* Results in an error.
label list foreign

* We need to first determine the value label of foreign:
describe foreign
label list origin

Write a program that avoids this intermediary step. Named varval, the program should take a varlist, then list the value label of each variable in the list.

There are a variety of solutions. Here's one:

program varval
    version 11
    syntax varlist(num)

    foreach var of local varlist {
        local lab : val lab `var'
        if "`lab'" != "" {
            disp _newline "{txt}Value label for {res:`var'}:"
            lab list `lab'
        }
    }
end

[hdiamondpollock]

Stata Training Course 151 could provide the basis for a future module on writing programs.

[hdiamondpollock]

See thread 'Random Help - Options for Options for an .ado" for an issue in writing programs

[matthew-white]

I just added this to the new Stata 151 milestone. Milestones are a good way to group together related issues. For example, I think your last comment is a distinct idea, so should be its own issue.