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MathGroup Archive 2005

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Mercator projection from with missing earth.pts

  • To: mathgroup at
  • Subject: [mg53250] Mercator projection from with missing earth.pts
  • From: Klamser at (klamser)
  • Date: Mon, 3 Jan 2005 04:29:27 -0500 (EST)
  • References: <cqtc4e$7ic$> <> <cr33o5$jcn$> <>
  • Sender: owner-wri-mathgroup at



everyone can get a notebook about the Mercator projection.

In this NB you can find the statement:

For a list of Eric's math packages that may be needed to evaluate this 
notebook, see  An archive of 
these packages may be downloaded from, as well as 
from the Mathematica Information Center's MathSource item 4775.  A list 
of Eric's utility packages that may be needed to evaluate this notebook 
may be downloaded from MathSource item 5087.

No problem downloading and installing

But it needs the file: earth.pts

But I don't know where I can find it. Internet search with google does 
not help.

No problem, I thought, because Mathematica obtains the 
<<Miscellaneous`WorldData` package.


wd = {#1, WorldData[#1]/60 // N} & /@ Map[ToString, World];
wd >> "c:\\z\\bin\\w.pts";

I can extract the Data an put it into a file, where 
MercatorProjection.nb can read it.

But it does not work.

The package << MathWorld`MapProjections` contains the code for reading 
the data:

MapCoordinates[opts___] := Module[
 {data, pos, dir = StringJoin[{MapDirectory,Directory} /. {opts} /.  
Options[MapCoordinates]], file = MapFile /. {opts} 
(*=>*) data = ReadList[dir <> file, Word, RecordLists -> 
True,WordSeparators -> {"\t", " "}, RecordSeparators -> {"\n"}];
(*=>*) pos = Flatten[Position[First /@ data, _?(StringTake[#, 1] == "#" 
(*=>*) ToExpression /@ Take[data, #] & /@ Transpose[{Most[pos + 1], 
Rest[pos - 1]}]Degree];

Can someone tell me,
a) where can I find a file earth.pts or
b) which format the earth.pts file must have, that the << 
MathWorld`MapProjections` package works fine.

Kind regards,

Peter Klamser

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