[R-sig-Geo] confused by coordinates

[Danlin Yu]

Zhijie:

Coordinates are probably very important in not only analysis in R, but in all environments that deal with spatial data analysis as well.

Difference between the geographical coordinates (Lat. and Long.) and the planar coordinates (the x and y) is basically the difference between spherical coordinates and Descartes' two-dimensional Cartesian coordinates. Distance measurement will be different. In addition, geographical coordinates are always associated with specific Datum (NAD27, NAD83, WGS84, etc.), with different Datum, the same location can have different Lat. and Long. Planar coordinates, on the other hand, in spatial data analysis, are usually not only associated with specific Datum, but specific projection as well (UTM, SPCS, etc.)

Coordinates are important in the field of Geology - I guess, but I would say coordinates are fundamental concepts from Cartography. Hence some good reference book in Cartography might provide further information on the question you ask.

Hope this helps.

Danlin Yu

___________________________________________
Danlin Yu, Ph.D.
Assistant Professor
Department of Earth & Environmental Studies
Montclair State University
Montclair, NJ, 07043
Tel: 973-655-4313
Fax: 973-655-4072
email: yud at mail.montclair.edu

----- Original Message -----
From: zhijie zhang <epistat at gmail.com>
Date: Wednesday, April 5, 2006 2:19 am
Subject: [R-sig-Geo] confused by coordinates

> Dear Friends,
>  Coordinate  is common in geology/spatial science. There are
> latitude/longitude coordinate, x/y coordinate,......... It maybe 
> easy for
> all of you, but difficult for persons without  the background 
> knowledge of
> geology, so they can't do the correct analysis with different 
> coordinate,.In my opinion, it's very important to make clear on it 
> and its application
> with R,  can anybody with excellent knowledge obout it  give some 
> guide on
> using it with R?
> For different coordinate,
> A:
> latitude    longitude   attribute
> 
> B:
> x   y   attribute
> 
> --
> Kind Regards,
> 
> 	[[alternative HTML version deleted]]
> 
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