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Ordnance Survey Ireland - Grid Reference Conversion
String Handling example from a Well House Consultants training course
More on String Handling [link]
Source code: irish_grid Module: Y108
import re
import sys """ A script to take Irish grid reference and validate them / convert them to eastings and northings. Ordnance Surver Ireland use an Easting and Northing grid system within 100 km squares which are lettered, across the island as per the table included in this file. There are then a number of formats that the data can be provided in. This Python script takes some sample references and validates them / reduces them to a standard form. """ # Table of grid reference letters: # ABCDE # FGHJK # LMNOP # QRSTU # VWXYZ # O00850,74150 Newgrange Neothlothic Tomb # or 300850,274150 # or O 008 741 # or O008741 # C95850,45450 Giant's Causeway, County Antrim lookup = { "A":[0,4], "B":[1,4], "C":[2,4], "D":[3,4], "E":[4,4], "F": [0,3], "G":[1,3], "H":[2,3], "J":[3,3], "K":[4,3], "L": [0,2], "M":[1,2], "N":[2,2], "O":[3,2], "P":[4,2], "Q": [0,1], "R":[1,1], "S":[2,1], "T":[3,1], "U":[4,1], "V": [0,0], "W":[1,0], "X":[2,0], "Y":[3,0], "Z":[4,0]} proper = re.compile(r'^(\d{1,6}),(\d{1,6})$') lettered = re.compile(r'^([A-Za-z])(\d{1,5}),(\d{1,5})$') short = re.compile(r'^([A-Za-z])\s*(\d{3})\s*(\d{3})$') # No parameters - run some sample gridrefs = ("123456,232313","117736,55432","H42314,53442", "534232,662313","hello","O00850,74150", "C95850,45450","O008741") # With parameters - use them if len(sys.argv) > 1: gridrefs = sys.argv[1:] for posn in gridrefs: got = proper.findall(posn) if got: easting = "%06d" % int(got[0][0]) northing = "%06d" % int(got[0][1]) else: got = lettered.findall(posn) if got: fareast = lookup[got[0][0].upper()][0] * 100000 farnorth = lookup[got[0][0].upper()][1] * 100000 easting = "%06d" % (int(got[0][1]) + fareast) northing = "%06d" % (int(got[0][2]) + farnorth) else: got = short.findall(posn) if got: fareast = lookup[got[0][0].upper()][0] * 100000 farnorth = lookup[got[0][0].upper()][1] * 100000 easting = "%06d" % ((100 * int(got[0][1])) + fareast) northing = "%06d" % ((100 * int(got[0][2])) + farnorth) if got: print(easting, northing, posn) else: print("nah",posn) """ Sample Outout WomanWithCat:y108 grahamellis$ python3 irish_grid 123456 232313 123456,232313 117736 055432 117736,55432 242314 353442 H42314,53442 534232 662313 534232,662313 nah hello 300850 274150 O00850,74150 295850 445450 C95850,45450 300800 274100 O008741 WomanWithCat:y108 grahamellis$ python2 irish_grid ('123456', '232313', '123456,232313') ('117736', '055432', '117736,55432') ('242314', '353442', 'H42314,53442') ('534232', '662313', '534232,662313') ('nah', 'hello') ('300850', '274150', 'O00850,74150') ('295850', '445450', 'C95850,45450') ('300800', '274100', 'O008741') WomanWithCat:y108 grahamellis$ """ Learn about this subject
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