Python functions to convert osgb36 (EPSG:27700) coordinates to/from 4, 6, 8, or 10 figure grid references
This script was originally published on of the Easily change coordinate projection systems in Python with pyproj blog post.
See blog post for more information and for details on converting other coordinate systems to osbg36.
The function converts between a bng grid reference as a string, and a tuple of OSGB36 (x,y) coordinates. When converting to bng coordinates, there is an opportunity to specify how many figures to use.
bng coordinates can be converted to osbg36 (EPSG:27700) coordinates as follows:
>>> import bng # import the bng module
>>> bng.to_osgb36('NT2755072950')
(327550, 672950)Combined with pyproj (see blog post), this can be converted to GPS coordinates.
>>> x, y = bng.to_osgb36('NT2755072950')
>>> pyproj.transform(osgb36, wgs84, x, y)
(-3.1615548588213667, 55.944109545140932)Use Python’s zip function handle multiple values:
>>> gridrefs = ['HU431392', 'SJ637560', 'TV374354']
>>> xy = bng.to_osgb36(gridrefs)
>>> x, y = zip(*xy)
>>> x
(443100, 363700, 537400)
>>> y
(1139200, 356000, 35400)You can convert OSGB36 coordinates to bng coordinates like this:
>>> bng.from_osgb36((327550, 672950))
'NT276730'Again, use the zip function for multiple values. You can also specify the number of figures:
>>> x = [443143, 363723, 537395]
>>> y = [1139158, 356004, 35394]
>>> xy = zip(x, y)
>>> bng.from_osgb36(xy, nDigits=4)
['HU4339', 'SJ6456', 'TV3735']Install dependencies:
pip install -r requirements.txtRun tests:
pytest -vs test_bng.py############################################################################
#
# COPYRIGHT: (C) 2012 John A Stevenson / @volcan01010
# Magnus Hagdorn
# WEBSITE: http://all-geo.org/volcan01010
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# http://www.gnu.org/licenses/gpl-3.0.html
#
#############################################################################