Mike Lacy writes in part:
> One feature of Stata with which I continue to experience difficulty
> concerns how to assign a value to a variable based on a run time
> contingency. As a simple illustration, consider the goal of assigning
> a uniform r.v. value to a variable, while rejecting values less than,
> say, 0.8. If -while- was sensitive to run time values of variables,
> I would do:
>
> gen x = uniform()
> while (x < 0.8) {
> replace x = uniform()
> }
>
> Obviously, this construct that would work in many languages does not
> work as desired in Stata, and just as obviously, there are other ways
> to accomplish the same end in Stata [ gen x = 0.8 + 0.2*uniform() ].
The general approach is to recognize that Stata is inherently vectorized.
Therefore,
. gen x = uniform()
. replace x = uniform() if x < 0.8
accomplishes what you want.
The above says replace x only if the currrent (run time) value of x is less than 0.8.
Tom
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