mirror of
https://github.com/wassname/PyCRS.git
synced 2026-06-27 16:10:29 +08:00
Karim Bahgat
99 lines
3.3 KiB
Python
99 lines
3.3 KiB
Python
import urllib2
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import re
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def build_crs_table(savepath):
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"""
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Build crs table of all equivalent format variations by scraping spatialreference.org.
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Saves table as tab-delimited text file.
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NOTE: Might take a while.
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Arguments:
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- *savepath*: The absolute or relative filepath to which to save the crs table, including the ".txt" extension.
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"""
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# create table
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outfile = open(savepath, "wb")
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# create fields
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fields = ["codetype", "code", "proj4", "ogcwkt", "esriwkt"]
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outfile.write("\t".join(fields) + "\n")
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# make table from url requests
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for codetype in ("epsg", "esri", "sr-org"):
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print(codetype)
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# collect existing proj list
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print("fetching list of available codes")
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codelist = []
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page = 1
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while True:
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try:
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link = 'http://spatialreference.org/ref/%s/?page=%s' %(codetype,page)
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html = urllib2.urlopen(link).read()
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codes = [match.groups()[0] for match in re.finditer(r'/ref/'+codetype+'/(\d+)', html) ]
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if not codes: break
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print("page",page)
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codelist.extend(codes)
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page += 1
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except:
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break
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print("fetching string formats for each projection")
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for i,code in enumerate(codelist):
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# check if code exists
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link = 'http://spatialreference.org/ref/%s/%s/' %(codetype,code)
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urllib2.urlopen(link)
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# collect each projection format in a table row
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row = [codetype, code]
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for resulttype in ("proj4", "ogcwkt", "esriwkt"):
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try:
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link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,resulttype)
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result = urllib2.urlopen(link).read()
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row.append(result)
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except:
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pass
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print("projection %i of %i added" %(i,len(codelist)) )
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outfile.write("\t".join(row) + "\n")
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# close the file
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outfile.close()
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def crscode_to_string(codetype, code, format):
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"""
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Lookup crscode on spatialreference.org and return in specified format.
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Arguments:
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- *codetype*: "epsg", "esri", or "sr-org".
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- *code*: The code.
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- *format*: The crs format of the returned string. One of "ogcwkt", "esriwkt", or "proj4", but also several others...
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Returns:
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- Crs string in the specified format.
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"""
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link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,format)
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result = urllib2.urlopen(link).read()
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return result
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##def crsstring_to_string(string, newformat):
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## """
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## Search unknown crs string for a match on spatialreference.org.
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## Not very reliable, the search engine does not properly lookup all text.
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## If string is correct there should only be one correct match.
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## Warning: Not finished yet.
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## """
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## link = 'http://spatialreference.org/ref/?search=%s' %string
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## searchresults = urllib2.urlopen(link).read()
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## # pick the first result
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## # ...regex...
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## # go to its url, with extension for the newformat
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## link = 'http://spatialreference.org/ref/%s/%s/%s/' %(codetype,code,newformat)
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## result = urllib2.urlopen(link).read()
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## return result
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