/usr/lib/python3/dist-packages/pyepsg.py is in python3-pyepsg 0.3.2-1.
This file is owned by root:root, with mode 0o644.
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#
# This file is part of pyepsg.
#
# pyepsg is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# pyepsg is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with pyepsg. If not, see <http://www.gnu.org/licenses/>.
"""
Provides simple access to http://epsg.io/.
The entry point for this package is the :func:`get()` function.
"""
from __future__ import print_function
import sys
import weakref
import xml.etree.ElementTree as ET
import requests
EPSG_IO_URL = 'http://epsg.io/'
GML_NS = '{http://www.opengis.net/gml/3.2}'
XLINK_NS = '{http://www.w3.org/1999/xlink}'
_cache = weakref.WeakValueDictionary()
class EPSG(object):
"""Parent class of all objects returned by pyepsg."""
def __init__(self, element):
self.element = element
@property
def identifier(self):
"""The official URN for this object."""
return self.element.find(GML_NS + 'identifier').text
class UOM(EPSG):
"""A unit of measure."""
@property
def name(self):
"""The human-readable name."""
return self.element.find(GML_NS + 'name').text
class Axis(EPSG):
"""A single coordinate axis."""
@property
def direction(self):
"""A description of the orientation of this axis."""
return self.element.find(GML_NS + 'axisDirection').text
@property
def uom(self):
"""The name of the unit of measure used on this axis."""
uom = self.element.attrib['uom']
return get(uom).name
def __repr__(self):
return '<Axis: {self.direction} / {self.uom}>'.format(self=self)
class CartesianCS(EPSG):
"""A 1-, 2-, or 3-dimensional cartesian coordinate system."""
@property
def axes(self):
"""An ordered list of :class:`Axis` objects describing X and Y."""
axes = self.element.findall(GML_NS + 'axis')
return [Axis(axis.find(GML_NS + 'CoordinateSystemAxis')) for
axis in axes]
@property
def name(self):
"""The human-readable name."""
return self.element.find(GML_NS + 'name').text
@property
def remarks(self):
"""Human-readable comments."""
return self.element.find(GML_NS + 'remarks').text
def __repr__(self):
name = self.name
if len(name) > 38:
name = name[:38] + '..'
return '<CartesianCS: {name}>'.format(name=name)
class CRS(EPSG):
"""
Abstract parent class for :class:`GeodeticCRS` and :class:`ProjectedCRS`.
"""
@property
def id(self):
"""The EPSG code for this CRS."""
id = self.element.attrib[GML_NS + 'id']
code = id.split('-')[-1]
return code
@property
def name(self):
"""The human-readable name."""
return self.element.find(GML_NS + 'name').text
@property
def scope(self):
"""A human-readable description of the intended usage for this CRS."""
return self.element.find(GML_NS + 'scope').text
def as_esri_wkt(self):
"""
Return the ESRI WKT string which corresponds to the CRS.
For example::
>>> print(get(27700).as_esri_wkt()) # doctest: +ELLIPSIS
PROJCS["OSGB_1936_British_National_Grid",GEOGCS["GCS_OSGB 19...
"""
url = '{prefix}{code}.esriwkt?download'.format(prefix=EPSG_IO_URL,
code=self.id)
return requests.get(url).text
def as_html(self):
"""
Return the OGC WKT which corresponds to the CRS as HTML.
For example::
>>> print(get(27700).as_html()) # doctest: +ELLIPSIS
<div class="syntax"><pre><span class="gh">PROJCS</span><span...
"""
url = '{prefix}{code}.html?download'.format(prefix=EPSG_IO_URL,
code=self.id)
return requests.get(url).text
def as_proj4(self):
"""
Return the PROJ.4 string which corresponds to the CRS.
For example::
>>> print(get(21781).as_proj4())
+proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 \
+k_0=1 +x_0=600000 +y_0=200000 +ellps=bessel \
+towgs84=674.4,15.1,405.3,0,0,0,0 +units=m +no_defs
"""
url = '{prefix}{code}.proj4?download'.format(prefix=EPSG_IO_URL,
code=self.id)
return requests.get(url).text.strip()
def as_wkt(self):
"""
Return the OGC WKT string which corresponds to the CRS.
For example::
>>> print(get(27700).as_wkt()) # doctest: +ELLIPSIS
PROJCS["OSGB 1936 / British National Grid",GEOGCS["OSGB 1936...
"""
url = '{prefix}{code}.wkt?download'.format(prefix=EPSG_IO_URL,
code=self.id)
return requests.get(url).text
def domain_of_validity(self):
"""
Return the domain of validity for this CRS as:
(west, east, south, north).
For example::
>>> print(get(21781).domain_of_validity())
[5.96, 10.49, 45.82, 47.81]
"""
# TODO: Generalise interface to return a polygon? (Can we find
# something that uses a polygon instead?)
domain = self.element.find(GML_NS + 'domainOfValidity')
domain_href = domain.attrib[XLINK_NS + 'href']
url = '{prefix}{code}.gml?download'.format(prefix=EPSG_IO_URL,
code=domain_href)
xml = requests.get(url).content
gml = ET.fromstring(xml)
def extract_bound(tag):
ns = '{http://www.isotc211.org/2005/gmd}'
xpath = './/{ns}EX_GeographicBoundingBox/{ns}{tag}/'.format(
ns=ns,
tag=tag)
bound = gml.find(xpath)
return float(bound.text)
tags = ('westBoundLongitude', 'eastBoundLongitude',
'southBoundLatitude', 'northBoundLatitude')
bounds = [extract_bound(tag) for tag in tags]
return bounds
class GeodeticCRS(CRS):
"""
Represents a single geodetic CRS.
"""
def __repr__(self):
return '<GeodeticCRS: {self.id}, {self.name}>'.format(self=self)
class ProjectedCRS(CRS):
"""
Represents a single projected CRS.
"""
@property
def base_geodetic_crs(self):
"""The :class:`GeodeticCRS` on which this projection is based."""
base = self.element.find(GML_NS + 'baseGeodeticCRS')
href = base.attrib[XLINK_NS + 'href']
return get(href)
@property
def cartesian_cs(self):
"""The :class:`CartesianCS` which describes the coordinate axes."""
cs = self.element.find(GML_NS + 'cartesianCS')
href = cs.attrib[XLINK_NS + 'href']
return get(href)
def __repr__(self):
return '<ProjectedCRS: {self.id}, {self.name}>'.format(self=self)
def get(code):
"""
Return an object that corresponds to the given EPSG code.
Currently supported object types are:
- :class:`GeodeticCRS`
- :class:`ProjectedCRS`
- :class:`CartesianCS`
- :class:`UOM`
For example::
>>> print(get(27700))
<ProjectedCRS: 27700, OSGB 1936 / British National Grid>
>>> print(get('4400-cs'))
<CartesianCS: Cartesian 2D CS. Axes: easting, northi..>
"""
instance = _cache.get(code)
if instance is None:
url = '{prefix}{code}.gml?download'.format(prefix=EPSG_IO_URL,
code=code)
xml = requests.get(url).content
root = ET.fromstring(xml)
class_for_tag = {
GML_NS + 'CartesianCS': CartesianCS,
GML_NS + 'GeodeticCRS': GeodeticCRS,
GML_NS + 'ProjectedCRS': ProjectedCRS,
GML_NS + 'BaseUnit': UOM,
}
if root.tag in class_for_tag:
instance = class_for_tag[root.tag](root)
else:
raise ValueError('Unsupported code type: {}'.format(root.tag))
_cache[code] = instance
return instance
if __name__ == '__main__':
import doctest
failure_count, test_count = doctest.testmod()
sys.exit(failure_count)
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