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"""
@package core.units
@brief Units management
.. todo::
Probably will be replaced by Python ctypes fns in the near future(?)
Usage:
from core.units import Units
Classes:
- units::BaseUnits
(C) 2009, 2011 by the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.
@author Martin Landa <landa.martin gmail.com>
"""
import math
if __name__ == "__main__":
import sys
class BaseUnits:
def __init__(self):
self._units = dict()
self._units["length"] = {
0: {"key": "mu", "label": _("map units")},
1: {"key": "me", "label": _("meters")},
2: {"key": "km", "label": _("kilometers")},
3: {"key": "mi", "label": _("miles")},
4: {"key": "ft", "label": _("feet")},
}
self._units["area"] = {
0: {"key": "mu", "label": _("sq map units")},
1: {"key": "me", "label": _("sq meters")},
2: {"key": "km", "label": _("sq kilometers")},
3: {"key": "ar", "label": _("acres")},
4: {"key": "ht", "label": _("hectares")},
}
def GetUnitsList(self, type):
"""Get list of units (their labels)
:param type: units type ('length' or 'area')
:return: list of units labels
"""
result = list()
try:
keys = sorted(self._units[type].keys())
for idx in keys:
result.append(self._units[type][idx]["label"])
except KeyError:
pass
return result
def GetUnitsKey(self, type, index):
"""Get units key based on index
:param type: units type ('length' or 'area')
:param index: units index
"""
return self._units[type][index]["key"]
def GetUnitsIndex(self, type, key):
"""Get units index based on key
:param type: units type ('length' or 'area')
:param key: units key, e.g. 'me' for meters
:return: index
"""
for k, u in self._units[type].items():
if u["key"] == key:
return k
return 0
Units = BaseUnits()
def ConvertValue(value, type, units):
"""Convert value from map units to given units
Inspired by vector/v.to.db/units.c
:param value: value to be converted
:param type: units type ('length', 'area')
:param unit: destination units
"""
# get map units
# TODO
f = 1
if type == "length":
if units == "me":
f = 1.0
elif units == "km":
f = 1.0e-3
elif units == "mi":
f = 6.21371192237334e-4
elif units == "ft":
f = 3.28083989501312
else: # -> area
if units == "me":
f = 1.0
elif units == "km":
f = 1.0e-6
elif units == "mi":
f = 3.86102158542446e-7
elif units == "ft":
f = 10.7639104167097
elif units == "ar":
f = 2.47105381467165e-4
elif units == "ht":
f = 1.0e-4
return f * value
def formatDist(distance, mapunits):
"""Formats length numbers and units in a nice way.
Formats length numbers and units as a function of length.
>>> formatDist(20.56915, 'metres')
(20.57, 'm')
>>> formatDist(6983.4591, 'metres')
(6.983, 'km')
>>> formatDist(0.59, 'feet')
(0.59, 'ft')
>>> formatDist(8562, 'feet')
(1.622, 'miles')
>>> formatDist(0.48963, 'degrees')
(29.38, 'min')
>>> formatDist(20.2546, 'degrees')
(20.25, 'deg')
>>> formatDist(82.146, 'unknown')
(82.15, 'units')
Accepted map units are 'meters', 'metres', 'feet', 'degree'.
Returns 'units' instead of unrecognized units.
:param distance: map units
:param mapunits: map units
From code by Hamish Bowman Grass Development Team 2006.
"""
if mapunits == "metres":
mapunits = "meters"
outunits = mapunits
distance = float(distance)
divisor = 1.0
# figure out which units to use
if mapunits == "meters":
if distance > 2500.0:
outunits = "km"
divisor = 1000.0
else:
outunits = "m"
elif mapunits == "feet":
# nano-bug: we match any "feet", but US Survey feet is really
# 5279.9894 per statute mile, or 10.6' per 1000 miles. As >1000
# miles the tick markers are rounded to the nearest 10th of a
# mile (528'), the difference in foot flavours is ignored.
if distance > 5280.0:
outunits = "miles"
divisor = 5280.0
else:
outunits = "ft"
elif "degree" in mapunits:
# was: 'degree' in mapunits and not haveCtypes (for unknown reason)
if distance < 1:
outunits = "min"
divisor = 1 / 60.0
else:
outunits = "deg"
else:
return (distance, "units")
# format numbers in a nice way
if (distance / divisor) >= 2500.0:
outdistance = round(distance / divisor)
elif (distance / divisor) >= 1000.0:
outdistance = round(distance / divisor, 1)
elif (distance / divisor) > 0.0:
outdistance = round(
distance / divisor, int(math.ceil(3 - math.log10(distance / divisor)))
)
else:
outdistance = float(distance / divisor)
return (outdistance, outunits)
def doc_test():
"""Tests the module using doctest
:return: a number of failed tests
"""
import doctest
from core.utils import do_doctest_gettext_workaround
do_doctest_gettext_workaround()
return doctest.testmod().failed
if __name__ == "__main__":
sys.exit(doc_test())
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