Bookmark and Share

Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: st: A bug in egen and gen?


From   David Kantor <kantor.d@att.net>
To   statalist@hsphsun2.harvard.edu
Subject   RE: st: A bug in egen and gen?
Date   Fri, 18 Feb 2011 10:56:13 -0500

At 09:43 PM 2/17/2011, Junlin wrote:
Unless someone changed the command, my version of Stata 11 does not compress double to float when it can do so. This is also indicated in the documentation. However, I can recast a variable to float if there is no loss of precision, otherwise I have to put in the /force option to force convert with loss of precision.

You may want to check
-ssc desc doubletofloat-

While -compress- does recast double to long, int or byte, it does not go double to float. Typing -recast float ...- is easy, but -doubletofloat- provides some additional convenience.

You may also be interested in
-ssc desc floattolong-
That does not save space, but recasts to a possibly more appropriate type.
I use long, int, or byte, (depending on the range) whenever the value are sure to be integer. What I'd like to see is an 8-byte integer type. Could be useful in some circumstances, for several reasons.

Finally, in response to Nick's comment,...

> You always have to tell -generate-, etc. what variable type you
> want created. On the whole, I don't think that would be a popular
> change.

This is my choice. Maybe it's a result of my programming background, but when I create a variable, the first thing I want to know is what data type it should be. What kinds of values -- integer or fractional? What range? Based on that, I choose the appropriate type. A command such as,
gen a = ...
looks risky to me, and I rarely do it. (I would do it only in manually-typed experiments. I would never do that in "live" work.) It could possibly have different results in different circumstances (depending on the default type). This habit is so ingrained, that I sometimes write,
gen float a = ...

In summary, I almost never depend on the default; I work as if the data type were a required feature of -gen- and -egen-.
HTH
--David

*
*   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/


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   Site index