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PyCRS/pycrs/parser.py
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# parse from text strings
# possible use module: https://github.com/rockdoc/grabbag/wiki/CRS-WKT-Parser
# also note some paramter descriptions: http://www.geoapi.org/3.0/javadoc/org/opengis/referencing/doc-files/WKT.html
# and see gdal source code: http://gis.stackexchange.com/questions/129764/how-are-esri-wkt-projections-different-from-ogc-wkt-projections
# especially: http://fossies.org/windows/misc/saga_2.1.4_x64.zip/saga_2.1.4_x64/saga_prj.dic
from . import datums
from . import ellipsoids
from . import parameters
from . import units
from . import projections
from . import webscrape
def from_epsg_code(code):
# must go online (or look up local table) to get crs details
code = str(code)
proj4 = webscrape.crscode_to_string("epsg", code, "proj4")
crs = from_proj4(proj4)
return crs
def from_esri_code(code):
# must go online (or look up local table) to get crs details
code = str(code)
proj4 = webscrape.crscode_to_string("esri", code, "proj4")
crs = from_proj4(proj4)
return crs
def from_sr_code(code):
# must go online (or look up local table) to get crs details
code = str(code)
proj4 = webscrape.crscode_to_string("sr-org", code, "proj4")
crs = from_proj4(proj4)
return crs
##def from_esri_wkt(string):
## # parse arguments into components
## # use args to create crs
## pass
def from_ogc_wkt(string):
# remove newlines and multi spaces
string = " ".join(string.split())
# parse arguments into components
def _consume_bracket(chars, char):
"char must be the opening bracket"
consumed = ""
depth = 1
while char and depth > 0:
consumed += char
char = next(chars, None)
# update depth level
if char == "[":
depth += 1
elif char == "]":
depth -= 1
consumed += char # consume the last closing char too
return consumed
def _consume_quote(chars, char, quotechar):
"char and quotechar must be the opening quote char"
consumed = ""
# consume the first opening char
consumed += char
char = next(chars, None)
# consume inside
while char and char != quotechar:
consumed += char
char = next(chars, None)
# consume the last closing char too
consumed += char
return consumed
def _next_elem(chars, char):
"char can be any char"
header = ""
# skip until next header
while not char.isalpha():
char = next(chars, None)
# first consume the element text header
while char.isalpha():
header += char
char = next(chars, None)
# skip until next brackets (in case of spaces)
while char != "[":
char = next(chars, None)
# then consume the element bracket contents
if char == "[":
content = _consume_bracket(chars, char)
char = next(chars, None)
# split content into args list
content = content[1:-1] # remove enclosing brackets
content = _split_except(content)
# recursively load all subelems
for i,item in enumerate(content):
if isinstance(item, str) and "[" in item:
chars = (char for char in item)
char = next(chars)
item = _next_elem(chars, char)
content[i] = item
return header, content
def _clean_value(string):
string = string.strip()
try: string = float(string)
except: pass
return string
def _split_except(string):
chars = (char for char in string)
char = next(chars)
items = []
consumed = ""
while char:
# dont split on quotes, just consume it
if char in ("'", '"'):
consumed += _consume_quote(chars, char, char)
# dont split inside brackets, just consume it
elif char == "[":
consumed += _consume_bracket(chars, char)
# make new splititem
elif char == ",":
consumed = _clean_value(consumed)
items.append(consumed)
consumed = ""
# consume normal char
elif char:
consumed += char
# next
char = next(chars, None)
# append last item too
consumed = _clean_value(consumed)
items.append(consumed)
return items
# load into nested tuples and arglists
crstuples = []
chars = (char for char in string)
char = next(chars)
while char:
header,content = _next_elem(chars, char)
crstuples.append((header, content))
char = next(chars, None)
# parse into actual crs objects
for header, content in crstuples:
# toplevel collection
if header.upper() == "PROJCS":
# find name
# find geogcs elem
# find projection elem
# find params
# find unit
pass
#projcs = parameters.ProjCS("Unknown", geogcs, proj, params, unit)
elif header.upper() == "GEOGCS":
pass
# use args to create crs
return crstuples
##def from_unknown_wkt(string):
## # detect if ogc wkt or esri wkt
## # TIPS: esri wkt datums all use "D_" before the datum name
## # then load with appropriate function
## pass
def from_proj4(string):
# parse arguments into components
# use args to create crs
# SLIGTHLY MESSY STILL, CLEANUP..
params = []
partdict = dict([part.split("=") for part in string.split()
if not part.startswith("+no_defs")])
# INIT CODES...?
# eg, +init=epsg code...?
if "+init" in partdict:
codetype, code = partdict["+init"].split(":")
if codetype == "EPSG":
crs = from_epsg_code(code)
# need to get individual elements from crs
# maybe from web...
# DATUM
# datum param is required
if "+datum" in partdict:
# get predefined datum def
for itemname in dir(datums):
item = getattr(datums, itemname)
try:
item = item()
if hasattr(item, "proj4") and partdict["+datum"] == item.proj4:
datumdef = item
break
except:
pass
else:
datumdef = datums.Unknown()
else:
datumdef = datums.Unknown()
# ELLIPS
# ellipse param is required
if "+ellps" in partdict:
# get predefined ellips def
for itemname in dir(ellipsoids):
item = getattr(ellipsoids, itemname)
try:
item = item()
if hasattr(item, "proj4") and partdict["+ellps"] == item.proj4:
ellipsdef = item
break
except:
pass
else:
raise Exception("Could not find required +ellps element")
# TO WGS 84 COEFFS
if "+towgs84" in partdict:
coeffs = partdict["+towgs84"].split(",")
datumshift = parameters.DatumShift(coeffs)
# if no datum, use ellips + towgs84 params to create the correct datum
# ...??
# COMBINE DATUM AND ELLIPS
## create datum and ellips param objs
ellips = parameters.Ellipsoid(ellipsdef,
semimaj_ax=partdict.get("+a"),
inv_flat=partdict.get("+f"))
if "+datum" in partdict:
datum = parameters.Datum(datumdef, ellips)
elif "+towgs84" in partdict:
datum = parameters.Datum(datumdef, ellips, datumshift)
else:
datum = parameters.Datum(datumdef, ellips)
# PRIME MERIDIAN
# set default
prime_mer = parameters.PrimeMeridian(0)
# overwrite with user input
if "+pm" in partdict:
# for now only support longitude, later add name support from below:
## greenwich 0dE
## lisbon 9d07'54.862"W
## paris 2d20'14.025"E
## bogota 74d04'51.3"E
## madrid 3d41'16.48"W
## rome 12d27'8.4"E
## bern 7d26'22.5"E
## jakarta 106d48'27.79"E
## ferro 17d40'W
## brussels 4d22'4.71"E
## stockholm 18d3'29.8"E
## athens 23d42'58.815"E
## oslo 10d43'22.5"E
prime_mer = parameters.PrimeMeridian(partdict["+pm"])
# ANGULAR UNIT
## proj4 cannot set angular unit, so just set to default
metmulti = parameters.MeterMultiplier(0.017453292519943295)
unittype = parameters.UnitType(units.Degree())
angunit = parameters.AngularUnit(unittype, metmulti)
# GEOGCS (note, currently does not load axes)
geogcs = parameters.GeogCS("Unknown", datum, prime_mer, angunit) #, twin_ax)
# PROJECTION
if "+proj" in partdict:
# get predefined proj def
for itemname in dir(projections):
item = getattr(projections, itemname)
try:
item = item()
if hasattr(item, "proj4") and partdict["+proj"] == item.proj4:
projdef = item
break
except:
pass
else:
projdef = None
else:
raise Exception("Could not find required +proj element")
if projdef:
# create proj param obj
proj = parameters.Projection(projdef)
# CENTRAL MERIDIAN
if "+lon_0" in partdict:
val = partdict["+lon_0"]
obj = parameters.CentralMeridian(val)
params.append(obj)
# FALSE EASTING
if "+x_0" in partdict:
val = partdict["+x_0"]
obj = parameters.FalseEasting(val)
params.append(obj)
# FALSE NORTHING
if "+y_0" in partdict:
val = partdict["+y_0"]
obj = parameters.FalseNorthing(val)
params.append(obj)
# SCALING FACTOR
if "+k_0" in partdict or "+k" in partdict:
if "+k_0" in partdict: val = partdict["+k_0"]
elif "+k" in partdict: val = partdict["+k"]
obj = parameters.ScalingFactor(val)
params.append(obj)
# LATITUDE ORIGIN
if "+lat_0" in partdict:
val = partdict["+lat_0"]
obj = parameters.LatitudeOrigin(val)
params.append(obj)
# LATITUDE TRUE SCALE
if "+lat_ts" in partdict:
val = partdict["+lat_ts"]
obj = parameters.LatitudeTrueScale(val)
params.append(obj)
# LONGITUDE CENTER
if "+lonc" in partdict:
val = partdict["+lonc"]
obj = parameters.LongitudeCenter(val)
params.append(obj)
# AZIMUTH
if "+alpha" in partdict:
val = partdict["+alpha"]
obj = parameters.Azimuth(val)
params.append(obj)
# STD PARALLEL 1
if "+lat1" in partdict:
val = partdict["+lat1"]
obj = parameters.LatitudeFirstStndParallel(val)
params.append(obj)
# STD PARALLEL 2
if "+lat2" in partdict:
val = partdict["+lat2"]
obj = parameters.LatitudeSecondStndParallel(val)
params.append(obj)
# UNIT
## set default
metmulti = parameters.MeterMultiplier(1.0)
unittype = parameters.UnitType(units.Meter())
## override with user input
if "+to_meter" in partdict:
metmulti = parameters.MeterMultiplier(partdict["+to_meter"])
if "+units" in partdict:
if partdict["+units"] == "m":
unittype = parameters.UnitType(units.Meter())
## create unitobj
unit = parameters.Unit(unittype, metmulti)
# SATELLITE HEIGHT
if "+h" in partdict:
val = partdict["+h"]
obj = parameters.SatelliteHeight(val)
params.append(obj)
# PROJCS
projcs = parameters.ProjCS("Unknown", geogcs, proj, params, unit)
# CRS
crs = parameters.CRS(projcs)
else:
crs = parameters.CRS(geogcs)
# FINISHED
return crs
##def from_ogc_urn(string):
## # hmmm, seems like ogc urn could be anything incl online link, epsg, etc...
## # if necessary, must go online (or lookup local table) to get details
## # maybe test which of these and run their function?
## # examples urn:ogc:def:crs:OGC:1.3:CRS1
## # or with EPSG instead of OGC
##
## # If OGC, 1.3 is pdf version, and after that is a name from list below
## # as found in pdf: "Definition identifier URNs in OGC namespace"
## # OGC crs definitions
## # URN | CRS name | Definition reference
## # urn:ogc:def:crs:OGC:1.3:CRS1 Map CS B.2 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:CRS84 WGS 84 longitude-latitude B.3 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:CRS83 NAD83 longitude-latitude B.4 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:CRS27 NAD27 longitude-latitude B.5 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:CRS88 NAVD 88 B.6 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:AUTO42001:99:8888 Auto universal transverse mercator B.7 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:AUTO42002:99:8888 Auto transverse mercator B.8 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:AUTO42003:99:8888 Auto orthographic B.9 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:AUTO42004:99:8888 Auto equirectangular B.10 in OGC 06-042
## # urn:ogc:def:crs:OGC:1.3:AUTO42005:99 Auto Mollweide B.11 in OGC 06-042
##
## pass
def from_unknown_text(text):
"""Detect type and load with appropriate function"""
if string.startswith("urn:"):
from_ogc_urn(string)
elif string.startswith("+proj="):
from_proj4(string)
elif string.startswith("PROJCS["):
from_unknown_wkt(string)
elif string.startswith("EPSG:"):
from_epsg_code(string.split(":")[1])
elif string.startswith("ESRI:"):
from_esri_code(string.split(":")[1])
elif string.startswith("SR-ORG:"):
from_sr_code(string.split(":")[1])
else: raise Exception("Could not detect which type of crs")
##def from_geotiff_parameters(**params):
## pass
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