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From |
"P. Wilner Jeanty" <pwjeanty@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: Nearstat version |

Date |
Mon, 6 Feb 2012 13:23:14 -0600 |

Nick and Brendan, Thanks for the comments and suggestions upon which I will cogitate for further improvements of -nearstat-. Wilner On Mon, Feb 6, 2012 at 11:41 AM, Nick Cox <njcoxstata@gmail.com> wrote: > In general I support programmers' rights (my program, my decision) but I > have to say that this sounds distinctly eccentric. So in a database of Stata > users if several people at StataCorp have the same coordinates the distance > between them is the distance to the nearest Stata user, say several miles > (km) away? To me it's zero. (Whether some purposes compel me to change zero > to some positive tolerance is a different issue.) > > I'd recommend to Wilner > > 1. Documenting this quirk in the help if that's not done already. I guess > most users of geographical data would regard it as a misfeature, to be > frank. > > 2. Even if this default is what you want consider adding an option to > override it. > > 3. In fact two options: zero means that; zero means a user-specfied > tolerance. > > Nick > > > On 6 Feb 2012, at 16:33, "P. Wilner Jeanty" <pwjeanty@gmail.com> wrote: > >> 2012/2/5 Rüdiger Vollmeier <ruediger.vollmeier@googlemail.com>: >>> >>> Thanks a lot for the good advice how to run the program. >>> >>> I ve got one question regarding the programming: It seems that in case >>> of non-identical observations with identical longitude and latitude, >>> the programs does not return the distance 0 but calculates the >>> shortest distance to non-identical latitude and longitudes. Am I >>> right? This is surprising and, I guess, for many users not desired. Is >>> it possible to change that (such that the distance 0 will be returned >>> in these cases)? >> >> >> >> This is a legitimate behavior by the program. Because it does not >> stand to reason that two different locations have identical latitudes >> and longitudes, -nearstat- thinks that it is computing the distance >> between an observation and itself. In order to identify the nearest >> neighbors (1st, 2nd, 3rd, and so forth), distance computed from an >> observation to itself is intentionally set to missing as part of the >> programming process. Ruediger's case where non-identical observations >> have identical latitudes and longitudes is an unusual one. As a >> result, I don't intend to modify -nearstat- to allow for it, at least >> not now, unless many users want this change to be made. Without more >> information, I find it odd that non-identical observations or areal >> units have identical latitudes and longitudes. >> >> FYI, a new version of -nearstat- with Mata code compiled in Stata 10.1 >> has been submitted to SSC. >> >> > > * > * 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/ * * 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/

**References**:**st: Re: Nearstat version***From:*"P. Wilner Jeanty" <pwjeanty@gmail.com>

**Re: st: Re: Nearstat version***From:*Nick Cox <njcoxstata@gmail.com>

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