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Re: st: SPHDIST, creating pairs
From
Austin Nichols <austinnichols@gmail.com>
To
statalist@hsphsun2.harvard.edu
Subject
Re: st: SPHDIST, creating pairs
Date
Thu, 25 Feb 2010 17:07:57 -0500
This was sent in plain text but seems in the archive to have gotten
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On Thu, Feb 25, 2010 at 4:39 PM, Austin Nichols <austinnichols@gmail.com> wrote:
> Tomeka Davis <soctmd@langate.gsu.edu> :
> This works fine for me:
> ssc inst vincenty
>
> From what Statalist post do you infer problems?
>
> Do you actually want to match all those pairs, or do you want to
> compute some statistic based on the distances? The latter does not
> require making a crossed file; see e.g.
> http://www.stata.com/statalist/archive/2009-09/msg00493.html
>
> On Thu, Feb 25, 2010 at 4:26 PM, Tomeka Davis <soctmd@langate.gsu.edu> wrote:
>> Hello -
>>
>> I am trying to calculate distance between two points using longitude and latitude data. I have come across 2 different Stata commands to do this - SPHDIST and VICENTY. I have not been able to install the VICENTY command. It appears from previous StataList posts that there might be problems associated with it and therefore it is temporarily unavailable (right?).
>>
>> Although I have longitude and latitude data, I am not sure how to create the pairs necessary to calculate distance with SPHDIST. I would like to calculate distance from a each public school in a district to all the other private schools in the same district. My data SHOULD look like this:
>>
>> District ID Public School ID Private School ID Public Longitude Public Latitude Private Latitude Private Longitude
>> 1 A 1
>> 1 A 2
>> 1 B 1
>> 1 B 2
>> 1 B 3
>> 1 B 4
>> 2 C 1
>> 2 C 2
>> 2 C 3
>> 2 D 1
>> 2 D 2
>>
>> I initially had two separate files; one with public school data and one with private school data. I appended the public school file and tacked on the private school data.
>>
>>
>> NOW the data looks something like this
>>
>> Distric ID School ID Public School Private School Latitude Longitude
>> 1 A Y N
>> 1 A Y N
>> 1 B Y N
>> 1 B Y N
>> 1 B Y N
>> 1 B Y N
>> 2 C N Y
>> 2 C N Y
>> 2 C N Y
>> 2 D N Y
>> 2 D N Y
>>
>>
>>
>> But I want to pair each public school with each private school.
>>
>> So far, I have figured out how to produce a data set pairing ALL schools within each district; this would pair public schools within a district with other public schools in the same district (using a an FAQ page from 2005 written by Nick Cox titled "Expanding datasets to all possible pairs"). However, I don't want this. I only want to pair each public school with each private school in the same district.
>>
>>
>> How do I accomplish this?
>>
>> I would appreciate any help anyone could offer. Also, any suggestions about the best distance command would be appreciated.
>>
>>
>
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