wiki:Geo_reference

Version 29 (modified by rwilson, 15 years ago) (diff)

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Internal Documentation/Classes


Class Geo_reference

Defined in file coordinate_transforms/geo_reference.py.

Discussion

Geo_reference Attributes

zone The UTM zone the Geo_reference is based in.
false_easting ??
false_northing ??
datum The datum used (default is 'wsg84').
projection The projection used (default is 'UTM').
units The units of measure used (default is metres, 'm').
xllcorner The X coordinate of origin (default is 0.0 with respect to the UTM grid origin).
yllcorner The Y coordinate of origin (default is 0.0 with respect to the UTM grid origin).

Geo_reference Methods

get_xllcorner(self) Returns the .xllcorner attribute.
get_yllcorner(self) Returns the .yllcorner attribute.
get_zone(self) Returns the .zone attribute.
write_NetCDF(self, outfile) Write Geo_reference attributes to an open NetCDF file at outfile. The attributes written are .xllcorner, .yllcorner, .zone, .false_easting, false_northing, .datum, .projection and .units.
read_NetCDF(self, infile) Read Geo_reference attributes from an open NetCDF file at infile. The attributes read are .xllcorner, .yllcorner, .zone, .false_easting, false_northing, .datum, .projection and .units.
write_ASCII(self, fd) Write Geo_reference attributes to an open ASCII file at fd. The attributes written are .zone, .xllcorner and .yllcorner.
read_ASCII(self, fd, read_title=None) Read Geo_reference attributes from an open ASCII file at fd. The attributes read are .zone, .xllcorner and .yllcorner. If read_title is None then we expect the title line in the data file to match the standard title in the first two characters. Otherwise read_title is the assumed title in the file which must match the standard title in the first two characters, and the title line is not read from the file.
change_points_geo_ref(self, points, points_geo_ref=None) Change the coordinates of a list or array of Points to be relative to a new Geo_reference. The new Point data is returned. Note that the input Point is also changed. If points_geo_ref is None then the coordinates are changed to be absolute with respect to the current Geo_reference.
is_absolute(self) Returns True if the Geo_reference origin is close to the UTM origin.
get_absolute(self, points) Given a list (or array) of Points geo-referenced to this Geo_reference, return a list (or array) of Points with absolute coordinates (ie, relative to the UTM origin). Note: also changes the input Point list! The inverse of get_relative().
get_relative(self, points) Given a list (or array) of Points geo-referenced to this Geo_reference, return a list (or array) of Points with relative coordinates (ie, relative to the Geo_reference origin). Note: also changes the input Point list! The inverse of get_absolute().
reconcile_zones(self, other) Compare two Geo_reference instances and reconcile the .zone attributes. If either instance (but not both) have a .zone of DEFAULT_ZONE then copy the .zone attribute from the instance with a real zone. Note: if other is None then assume a default Geo_reference instance.
get_origin(self) Returns a tuple of (.zone, .xllcorner, .yllcorner) for the instance. Note: should use this method and delete methods get_xllcorner(), get_yllcorner() and get_zone().
_ _cmp_ _(self, other) Allows python code to directly compare two Geo_reference instances. Two instances are equal if their .zone, .xllcorner and yllcorner attributes are the same.

Notes

There is a lot of room for error in handling Point and Geo_reference instances. The Geo_spatial class includes instances of these two classes.

This class is defined in the 'old' way. Needs to be changed to the new method before moving to python 2.6.


Internal Documentation/Classes