earlier post "Calculate distances in a file with latitude and longitude"

[Art Kendall]

*Jon Peck posted a reply to this but in the archives the message is scrambled.
Did anyone happen to save that post? If so would you email it to me?

Date:*          Mon, 20 Feb 2012 15:27:07 -0700
*Reply-To:*      Jon K Peck<[hidden email]>
*Sender:*        "SPSSX(r) Discussion"<[hidden email]>
*From:*          Jon K Peck<[hidden email]>  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=36443>
*Subject:*       Re: Calculate distances in a file with latitude and longitude  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=38463>

--
Art Kendall
Social Research Consultants

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[Bruce Weaver]

Hi Art.  It looks okay in the Nabble archive--see the second post here:

http://spssx-discussion.1045642.n5.nabble.com/Calculate-distances-in-a-file-with-latitude-and-longitude-td5500259.html#a5503755

Art Kendall wrote

*Jon Peck posted a reply to this but in the archives the message is scrambled.
Did anyone happen to save that post? If so would you email it to me?

Date:*          Mon, 20 Feb 2012 15:27:07 -0700
*Reply-To:*      Jon K Peck<[hidden email]>
*Sender:*        "SPSSX(r) Discussion"<[hidden email]>
*From:*          Jon K Peck<[hidden email]>  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=36443>
*Subject:*       Re: Calculate distances in a file with latitude and longitude  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=38463>

--
Art Kendall
Social Research Consultants

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[Jon K Peck]

If you just want to calculate distances and have installed the SPSSINC TRANS extension command and the extendedTransforms.py module, you can run something like this.

spssinc trans result=distance
/formula "extendedTransforms.ellipseDist(latitude1, longitude1, latitude2, longitude2, inradians=False)".

for positions in degrees.  If in radians, change inradians to True.

Jon Peck (no "h") aka Kim
Senior Software Engineer, IBM
[hidden email]
new phone: [phone]




From:        Art Kendall <[hidden email]>
To:        [hidden email]
Date:        06/02/2012 07:16 AM
Subject:        [SPSSX-L] earlier post "Calculate distances in a file with              latitude and              longitude"
Sent by:        "SPSSX(r) Discussion" <[hidden email]>

---

*Jon Peck posted a reply to this but in the archives the message is scrambled.
Did anyone happen to save that post? If so would you email it to me?

Date:*          Mon, 20 Feb 2012 15:27:07 -0700
*Reply-To:*      Jon K Peck<[hidden email]>
*Sender:*        "SPSSX(r) Discussion"<[hidden email]>
*From:*          Jon K Peck<[hidden email]>  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=36443>
*Subject:*       Re: Calculate distances in a file with latitude and longitude  <http://listserv.uga.edu/cgi-bin/wa?A2=ind1202&L=spssx-l&D=0&P=38463>

--
Art Kendall
Social Research Consultants

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[Richard Ristow]

At 09:12 AM 6/2/2012, Art Kendall wrote:

>*Jon Peck posted a reply to this but in the archives the message is scrambled.
>Did anyone happen to save that post? If so would you email it to me?

Perhaps the following will help. It's from a (probably
over-elaborate) post I wrote on the subject, back in 2009(*):

FAQ: Computing distance from latitude and longitude (DRAFT)

Sections below are
===== (1) Solution in native SPSS transformation code
===== (2) Using Python code from Developer Central
===== (3) Test data and test run of native SPSS code


===== (1) Native SPSS code =====================================
Earth-radius values are from
http://en.wikipedia.org/wiki/Earth_radius; see also
http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html.

*  ...............   Initialize constants      ................. .


*  The following code >REQUIRES< that angles in the base system  .
*  (SPSS) be in radians, so that the trigonometric distance is   .
*  in radians, and can be multiplied directly by the Earth's     .
*  radius.                                                       .

DO IF $CASENUM EQ 1.
*  These initializations >MUST< be performed:                    .
*  #EarthRad is the Earth's radius in whatever units you please; .
*  the calculated distance will be in those units:               .
*              6,372.7976    km,                                 .
*              3,959.873     statute miles,                      .
*              3,441.035     nautical miles.                     .
.  COMPUTE
    #EarthRad =  3959.873  /* statute miles */.

*  #AngleCvt is the number of your angle units (degrees, here)   .
*  in one of SPSS's angle units (radians). It uses that          .
*  ARCTAN(1)is PI/4 radians or (in any angle measure) 1/8 circle .
.
.  COMPUTE
    #AngleCvt =  360  /* Number of input units in a full circle */
               /(8*ARTAN(1)).

END IF.

*  ...............   Compute distance          ................  .
*  Compute distance between points with coordinates              .
*  (lat1,lon1) and (lat2,lon2)                                   .

compute distance = #EarthRad*
     (2*artan(1)-arsin(      sin(lat1/#AngleCvt)   /* (sin(lat1)  */
                            *sin(lat2/#AngleCvt)   /* .sin(lat2)  */
                          +  cos(lat1/#AngleCvt)   /* +cos(lat1)  */
                            *cos(lat2/#AngleCvt)   /* .cos(lat2)  */
                            *cos(lon2/#AngleCvt    /* .cos(long2  */
                                -lon1/#AngleCvt)   /*     -long1))*/
                       )).

FORMAT    Distance (F7.2).


===== (2) Using Python code ====================================
 From Peck, Jon, "Re: Function for arc cosine", to SPSSX-L Thu, 7 Jun
2007 09:53:06 -0500""

"In the extendedTransforms module on SPSS Developer Central (
www.spss.com/devcentral), there are two functions that implement
distance calculations on Earth latitude and longitude coordinates.

sphDist:     calculate distance between two points on earth using
spherical approximation
ellipseDist: calculate distance between two points on earth using
ellipsoidal approximation

"Here is a simple usage example for just a single distance pair.
.............

begin program.
import spss
import extendedTransforms

fromloc = (41.90, 87.65)
toloc = (41.73, 71.43)
dist1 = extendedTransforms.ellipseDist(fromloc[0], fromloc[1],
toloc[0], toloc[1], inradians=False)
dist2 = extendedTransforms.sphDist(fromloc[0], fromloc[1], toloc[0],
toloc[1], inradians=False)
print dist1, dist2

end program.

(3) =====  Test data, and test run  =================================
The 'given' values which are compared with the calculation are,

. Providence to Chicago distance, from Jon Peck's posting "Re:
Function for arc cosine", Thu, 7 Jun 2007 09:53:06 -0500

. Others, arbitrary test points with distance calculated at site
http://www.movable-type.co.uk/scripts/latlong.html. It's not clear
why tiny discrepancies remain.


DATA LIST LIST /
    City1    lat1    lon1 City2    lat2    lon2   GivenDist
    (A4,     F6.2,   F6.2,A4,      F6.2,   F6.2,  F7.2).
BEGIN DATA
    Pvd     41.90   87.65 Chi     41.73   71.43   836.27
    A1      42.00   80.00 A2      39.00   70.00   564.33
    B1      44.00   70.00 B2      49.00   85.00   791.00
END DATA.

.  /*--  LIST /*-*/.


*  ...............   Initialize constants      ................. .

*  The following code >REQUIRES< that angles in the base system  .
*  (SPSS) be in radians, so that the trigonometric distance is   .
*  in radians, and can be multiplied directly by the Earth's     .
*  radius.                                                       .

DO IF $CASENUM EQ 1.
*  These initializations >MUST< be performed:                    .
*  #EarthRad is the Earth's radius in whatever units you please; .
*  the calculated distance will be in those units:               .
*              6,372.7976    km,                                 .
*              3,959.873     statute miles,                      .
*              3,441.035     nautical miles.                     .
.  COMPUTE
    #EarthRad =  3959.873  /* statute miles */.

*  #AngleCvt is the number of your angle units (degrees, here)   .
*  in one of SPSS's angle units (radians). It uses that          .
*  ARCTAN(1)is PI/4 radians or (in any angle measure) 1/8 circle .
.
.  COMPUTE
    #AngleCvt =  360  /* Number of input units in a full circle */
               /(8*ARTAN(1)).

END IF.

*  ...............   Compute distance          ................  .
*  Compute distance between points with coordinates              .
*  (lat1,lon1) and (lat2,lon2)                                   .

compute distance = #EarthRad*
     (2*artan(1)-arsin(      sin(lat1/#AngleCvt)   /* (sin(lat1)  */
                            *sin(lat2/#AngleCvt)   /* .sin(lat2)  */
                          +  cos(lat1/#AngleCvt)   /* +cos(lat1)  */
                            *cos(lat2/#AngleCvt)   /* .cos(lat2)  */
                            *cos(lon2/#AngleCvt    /* .cos(long2  */
                                -lon1/#AngleCvt)   /*     -long1))*/
                       )).

FORMAT    GivenDist(F7.2).

COMPUTE   DeltaPct = 100*(Distance/GivenDist-1).
FORMATS   DeltaPct (PCT7.2).

LIST.

List
|-----------------------------|---------------------------|
|Output Created               |29-MAR-2009 00:55:20       |
|-----------------------------|---------------------------|
City1    lat1    lon1 City2    lat2    lon2 GivenDist distance DeltaPct

Pvd     41.90   87.65 Chi     41.73   71.43   836.27    834.33    -.23%
A1      42.00   80.00 A2      39.00   70.00   564.33    564.52     .03%
B1      44.00   70.00 B2      49.00   85.00   791.00    791.03     .00%

Number of cases read:  3    Number of cases listed:  3
=========================================================
(*) From posting,
Date:    Sun, 29 Mar 2009 00:57:59 -0400
From:    Richard Ristow <[hidden email]>
Subject: Re: Calculating distance between latitude and longitude
To:      [hidden email]

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