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# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
from __future__ import (absolute_import, division, print_function,
unicode_literals)
import numpy as np
__doctest_skip__ = ['quantity_support']
def quantity_support(format='latex_inline'):
"""
Enable support for plotting `astropy.units.Quantity` instances in
matplotlib.
May be (optionally) used with a ``with`` statement.
>>> import matplotlib.pyplot as plt
>>> from astropy import units as u
>>> from astropy import visualization
>>> with visualization.quantity_support():
... plt.figure()
... plt.plot([1, 2, 3] * u.m)
[...]
... plt.plot([101, 125, 150] * u.cm)
[...]
... plt.draw()
Parameters
----------
format : `astropy.units.format.Base` instance or str
The name of a format or a formatter object. If not
provided, defaults to ``latex_inline``.
"""
from .. import units as u
from matplotlib import units
from matplotlib import ticker
def rad_fn(x, pos=None):
n = int((x / np.pi) * 2.0 + 0.25)
if n == 0:
return '0'
elif n == 1:
return 'π/2'
elif n == 2:
return 'π'
elif n % 2 == 0:
return '{0}π'.format(n / 2)
else:
return '{0}π/2'.format(n)
class MplQuantityConverter(units.ConversionInterface):
def __init__(self):
if u.Quantity not in units.registry:
units.registry[u.Quantity] = self
self._remove = True
else:
self._remove = False
@staticmethod
def axisinfo(unit, axis):
if unit == u.radian:
return units.AxisInfo(
majloc=ticker.MultipleLocator(base=np.pi/2),
majfmt=ticker.FuncFormatter(rad_fn),
label=unit.to_string(),
)
elif unit == u.degree:
return units.AxisInfo(
majloc=ticker.AutoLocator(),
majfmt=ticker.FormatStrFormatter('%i°'),
label=unit.to_string(),
)
elif unit is not None:
return units.AxisInfo(label=unit.to_string(format))
return None
@staticmethod
def convert(val, unit, axis):
if isinstance(val, u.Quantity):
return val.to(unit).value
else:
return val
@staticmethod
def default_units(x, axis):
if hasattr(x, 'unit'):
return x.unit
return None
def __enter__(self):
return self
def __exit__(self, type, value, tb):
if self._remove:
del units.registry[u.Quantity]
return MplQuantityConverter()
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