I need help with prog
Answer:
Stata programming is not difficult since it mainly involves the use of Stata commands that you already use. The trick to Stata programming is to use the appropriate commands in the right sequence. Of course, this is the trick to any kind of programming.
There are two kinds of files that are used in Stata programming, do-files and ado-files. Do-files are run from the command line using the do command, for example,
do hsbcheck hsberr
Ado-files, on the other hand, work like ordinary Stata commands by just using the file name in the command line, for example,
ttest write, by(female)
In fact, many of the built-in Stata commands are just ado-files, like the ttest command shown above. You can look at the source code for the ado commands using the viewsource command, for example,
viewsource ttest.ado
You can also use viewsource with your do-files.
viewsource hsbcheck.do
Programs and ado-files are the main methods by which Stata code is condensed and generalized.
The program command sets up the code environment for writing a program into memory.
The syntax command parses inputs into a program as macros that can be used within the scope of that program execution.
The tempvar, tempfile, and tempname commands all create objects that can be used within the scope of program execution to avoid any conflict with arbitrary data structures.
The program command
The program command defines the scope of a Stata program inside a do-file or ado-file. When a program command block is executed, Stata stores (until the end of the session) the sequence of commands written inside the block and assigns them to the command name used in the program command. Using program drop before the block will ensure that the command space is available. For example, we might write the following program in an ordinary do-file:
cap prog drop autoreg
prog def autoreg
reg price mpg i.foreign
end
After executing this command block we could run:
sysuse auto.dta , clear
autoreg
If we did this, Stata would output:
. autoreg
Source | SS df MS Number of obs = 74
-------------+---------------------------------- F(2, 71) = 14.07
Model | 180261702 2 90130850.8 Prob > F = 0.0000
Residual | 454803695 71 6405685.84 R-squared = 0.2838
-------------+---------------------------------- Adj R-squared = 0.2637
Total | 635065396 73 8699525.97 Root MSE = 2530.9
------------------------------------------------------------------------------
price | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
mpg | -294.1955 55.69172 -5.28 0.000 -405.2417 -183.1494
|
foreign |
Foreign | 1767.292 700.158 2.52 0.014 371.2169 3163.368
_cons | 11905.42 1158.634 10.28 0.000 9595.164 14215.67
All this is to say is that Stata has taken the command reg price mpg i.foreign and will execute it whenever autoreg is run as if it were an ordinary command.
The syntax command
The syntax command takes a program block and allows its inputs to be customized based on the context it is being executed in. The syntax command enables all the main features of Stata that appear in ordinary commands, including input lists if and in restrictions, using targets, = applications, weights, and options
.For now, we will take a simple tour of how syntax creates an adaptive command.
First, let's add simple syntax allowing the user to select the variables and observations they want to include. We might write:
cap prog drop levelslist
prog def levelslist
syntax anything [if]
preserve
// Implement [if]
marksample touse
qui keep if `touse' == 1
// Main program loops
foreach var of varlist `anything'
{
qui levelsof `var' , local(levels)
di " "
di "Levels of `var': `: var label `var''"
foreach word in `levels'
{
di " `word'"
}
}
End
The temp commands
Stata has a set of temp commands that can be used to store information temporarily. This functionality
Categories:
Coding Practices
Stata Coding Practices
Step by step
Solved in 2 steps
