mirror of
https://github.com/wassname/PyCRS.git
synced 2026-06-27 16:10:29 +08:00
Karim Bahgat
86 lines
2.2 KiB
Python
86 lines
2.2 KiB
Python
"""
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Convenience functions for loading from different sources.
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"""
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import json
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import urllib2
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from . import parser
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#################
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# USER FUNCTIONS
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#################
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def from_url(url, format=None):
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"""
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Returns the crs object from a string interpreted as a specified format, located at a given url site.
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Arguments:
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- *url*: The url where the crs string is to be read from.
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- *format* (optional): Which format to parse the crs string as. One of "ogc wkt", "esri wkt", or "proj4".
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If None, tries to autodetect the format for you (default).
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Returns:
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- CRS object.
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"""
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# first get string from url
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string = urllib2.urlopen(url).read()
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# then determine parser
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if format:
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# user specified format
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format = format.lower().replace(" ", "_")
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func = parser.__getattr__("from_%s" % format)
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else:
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# unknown format
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func = parser.from_unknown_text
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# then load
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crs = func(string)
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return crs
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def from_file(filepath):
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"""
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Returns the crs object from a file, with the format determined from the filename extension.
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Arguments:
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- *filepath*: filepath to be loaded, including extension.
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"""
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if filepath.endswith(".prj"):
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string = open(filepath, "r").read()
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return parser.from_esri_wkt(string)
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elif filepath.endswith((".geojson",".json")):
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raw = open(filepath).read()
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geoj = json.loads(raw)
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if "crs" in geoj:
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crsinfo = geoj["crs"]
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if crsinfo["type"] == "name":
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string = crsinfo["properties"]["name"]
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return parser.from_unknown_text(string)
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elif crsinfo["type"] == "link":
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url = crsinfo["properties"]["name"]
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type = crsinfo["properties"].get("type")
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return loader.from_url(url, format=type)
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else: raise Exception("invalid geojson crs type: must be either name or link")
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else:
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# assume default wgs84 as per the spec
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return parser.from_epsg_code("4326")
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## elif filepath.endswith((".tif",".tiff",".geotiff")):
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## pass
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## # ...
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