[R] converting lat-long coordinates to Albers Conical Equal Area coordinates

[jatwood]

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We have used maptools to construct state, county, township, census-tract, 
and zipcode
level R maps with an Albers Conical Equal Area projection.  We would like 
to be able to
plot the location of weather stations or other point locations on the 
maps.  The data
the point locations are in latitude-longitude units and we must convert the 
coordinates
to the Albers Conical Equal Area coordinates.

However, as of yet, we have not been able to obtain satisfactory results 
using mapproj.
Given the specs below can someone please tell us how to use mapproj (or 
some other R
library) to convert lat-long coordinates into the appropriate Albers 
Conical Equal Area
coordinates?

Thanks in advance
Joe Atwood
Montana State University
jatwood at montana.edu

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The material at the bottom of this message is the metadata from
the shapefile we are using (as created in Arc-GIS).
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-----------------------------------
Horizontal coordinate system
Projected coordinate system name: NAD_1927_Albers
Geographic coordinate system name: GCS_North_American_1927
Details
Map Projection Name: Albers Conical Equal Area
Standard Parallel: 29.500000
Standard Parallel: 45.500000
Longitude of Central Meridian: -96.000000
Latitude of Projection Origin: 23.000000
False Easting: 0.000000
False Northing: 0.000000


Planar Coordinate Information
Planar Distance Units: meters
Coordinate Encoding Method: coordinate pair
Coordinate Representation
Abscissa Resolution: 0.008192
Ordinate Resolution: 0.008192


Geodetic Model
Horizontal Datum Name: North American Datum of 1927
Ellipsoid Name: Clarke 1866
Semi-major Axis: 6378206.400000
Denominator of Flattening Ratio: 294.978698
_________________

Bounding coordinates
Horizontal
In decimal degrees
West: -127.889829
East: -65.349890
North: 51.606167
South: 22.862978
In projected or local coordinates
Left: -2356341.706499
Right: 2257925.009693
Top: 3172647.320063
Bottom: 268329.067476

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