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MathGroup Archive 1998

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Re: Re: Better WorldPlot data?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg13103] Re: [mg13090] Re: Better WorldPlot data?
  • From: Wouter Meeussen <eu000949 at pophost.eunet.be>
  • Date: Tue, 7 Jul 1998 03:44:08 -0400
  • Sender: owner-wri-mathgroup at wolfram.com

hi all,

please take *speed* into consideration. Plotting charts is very slow
even now. I would be more charmed with a reduced data set in which the
common borders between countries would be somehow linked ; this would
enable me to generate deformed charts where the area of a country is
proportional to its *population* (or any other property I want to
visualise). I've seen maps like that, and they were marvellous. It
would enable us to treat the dataset as more than a set of lines, more
like a graph (with all goodies in the DiscreteMath package applicable)

to show my constructive attitude (:-), here are a few lines of code that
enable you to plot great arcs :
****************************************************************************
<<Miscellaneous`WorldPlot`
<<Miscellaneous`CityData`

m2r[z_]:=N[z/60/180*Pi]
r2m[z_]:=N[z/Pi*60*180]

greatcircle[tok_List,hon_List,n_Integer]:=
Module[{t=tok[[2]],h=hon[[2]]},
	If[Abs[t-h]<=180*60,
		{Table[{r2m at Li[m2r@\[Lambda]x,m2r at tok,m2r at hon],\[Lambda]x},{\[Lambda]x,h
,
              t,(t-h)/n}]//N},
          
{Table[{r2m at Li[m2r@\[Lambda]x,m2r at tok,m2r at hon],\[Lambda]x},{\[Lam
bda]x,
              Max[t,h],180*60,(180*60-Max[t,h])/n}]//N,
			Table[{r2m at Li[m2r@\[Lambda]x,m2r at tok,m2r at hon],\[Lambda]x},{
              \[Lambda]x,-180*60,Min[t,h],(Min[t,h]+180*60)/n }]//N
	}]]

hon=CityData["Honolulu", CityPosition]//ToMinutes
ist=CityData["Istanbul", CityPosition]//ToMinutes rom=CityData["Rome",
CityPosition]//ToMinutes

Show[{wpm,WorldGraphics[{
	Hue[0.0],  Thickness[0.005],Line/@greatcircle[hon,rom,40],	
        Hue[0.5],                   Line/@greatcircle[hon,ist,40]      
			}]
    }]
****************************************************************************
***************

wouter.

At 03:37 5-07-98 -0400, David Reiss wrote:
>In article <6nc6qv$fb1 at smc.vnet.net>, Sigurd Tjelmeland <sigurd at imr.no>
>wrote:
>
>> >
>> 
>> Does anyone know of any better WorldData databases than the one that
>> comes with Mathematica? There are two few points, and the countries get
>> a rather ugly shape. For the geographical area in which I work
>> (North-east Atlantic) I took data from the GEBCO base and transformed
>> to Mathematica lists. I am interested in Mathematica lists around the
>> globe for areas north of 50 N. My lists are of course available for
>> those interested.
>> 
>> Sigurd Tjelmeland
>> 
>> Institute of Marine Research
>> Bergen, Norway
>> 
>> sigurd at imr.no
>
>I would be very heplful to Mathematica users if you would  post your
>datasets to MathSource (www.mathsource.com). I think that WorldPlot
>could be made more usesful if the  database for it were more up to
>date, of higher resolution, and generally more detailed.  If anyone
>else has other data sets for use in WorldPlot, MathSource would welcome
>them with open arms (files?).
>
>Also, could you describe the  GEBCO base further? 
>
>Thanks, 
>
>David Reiss 
>
>("editor-at-large" for MathSource)
>
>-- 
>David Reiss
>dreissNOSPAM at nospam.earthlink.net
>http://home.earthlink.net/~dreiss
>To send personal email, remove the words  "nospam" and "NOSPAM" from the
>email address
>
>
Dr. Wouter L. J. MEEUSSEN
w.meeussen.vdmcc at vandemoortele.be
eu000949 at pophost.eunet.be



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