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import textwrap
import numpy as np
from numpy import ma
MaskedArray = ma.MaskedArray
from cbook import dedent
from ticker import NullFormatter, ScalarFormatter, LogFormatterMathtext, Formatter
from ticker import NullLocator, LogLocator, AutoLocator, SymmetricalLogLocator, FixedLocator
from transforms import Transform, IdentityTransform
from matplotlib import docstring
class ScaleBase(object):
"""
The base class for all scales.
Scales are separable transformations, working on a single dimension.
Any subclasses will want to override:
- :attr:`name`
- :meth:`get_transform`
And optionally:
- :meth:`set_default_locators_and_formatters`
- :meth:`limit_range_for_scale`
"""
def get_transform(self):
"""
Return the :class:`~matplotlib.transforms.Transform` object
associated with this scale.
"""
raise NotImplementedError
def set_default_locators_and_formatters(self, axis):
"""
Set the :class:`~matplotlib.ticker.Locator` and
:class:`~matplotlib.ticker.Formatter` objects on the given
axis to match this scale.
"""
raise NotImplementedError
def limit_range_for_scale(self, vmin, vmax, minpos):
"""
Returns the range *vmin*, *vmax*, possibly limited to the
domain supported by this scale.
*minpos* should be the minimum positive value in the data.
This is used by log scales to determine a minimum value.
"""
return vmin, vmax
class LinearScale(ScaleBase):
"""
The default linear scale.
"""
name = 'linear'
def __init__(self, axis, **kwargs):
pass
def set_default_locators_and_formatters(self, axis):
"""
Set the locators and formatters to reasonable defaults for
linear scaling.
"""
axis.set_major_locator(AutoLocator())
axis.set_major_formatter(ScalarFormatter())
axis.set_minor_locator(NullLocator())
axis.set_minor_formatter(NullFormatter())
def get_transform(self):
"""
The transform for linear scaling is just the
:class:`~matplotlib.transforms.IdentityTransform`.
"""
return IdentityTransform()
def _mask_non_positives(a):
"""
Return a Numpy masked array where all non-positive values are
masked. If there are no non-positive values, the original array
is returned.
"""
mask = a <= 0.0
if mask.any():
return ma.MaskedArray(a, mask=mask)
return a
def _clip_non_positives(a):
a[a <= 0.0] = 1e-300
return a
class LogScale(ScaleBase):
"""
A standard logarithmic scale. Care is taken so non-positive
values are not plotted.
For computational efficiency (to push as much as possible to Numpy
C code in the common cases), this scale provides different
transforms depending on the base of the logarithm:
- base 10 (:class:`Log10Transform`)
- base 2 (:class:`Log2Transform`)
- base e (:class:`NaturalLogTransform`)
- arbitrary base (:class:`LogTransform`)
"""
name = 'log'
class LogTransformBase(Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, nonpos):
Transform.__init__(self)
if nonpos == 'mask':
self._handle_nonpos = _mask_non_positives
else:
self._handle_nonpos = _clip_non_positives
class Log10Transform(LogTransformBase):
base = 10.0
def transform(self, a):
a = self._handle_nonpos(a * 10.0)
if isinstance(a, MaskedArray):
return ma.log10(a)
return np.log10(a)
def inverted(self):
return LogScale.InvertedLog10Transform()
class InvertedLog10Transform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
base = 10.0
def transform(self, a):
return ma.power(10.0, a) / 10.0
def inverted(self):
return LogScale.Log10Transform()
class Log2Transform(LogTransformBase):
base = 2.0
def transform(self, a):
a = self._handle_nonpos(a * 2.0)
if isinstance(a, MaskedArray):
return ma.log(a) / np.log(2)
return np.log2(a)
def inverted(self):
return LogScale.InvertedLog2Transform()
class InvertedLog2Transform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
base = 2.0
def transform(self, a):
return ma.power(2.0, a) / 2.0
def inverted(self):
return LogScale.Log2Transform()
class NaturalLogTransform(LogTransformBase):
base = np.e
def transform(self, a):
a = self._handle_nonpos(a * np.e)
if isinstance(a, MaskedArray):
return ma.log(a)
return np.log(a)
def inverted(self):
return LogScale.InvertedNaturalLogTransform()
class InvertedNaturalLogTransform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
base = np.e
def transform(self, a):
return ma.power(np.e, a) / np.e
def inverted(self):
return LogScale.NaturalLogTransform()
class LogTransform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, base, nonpos):
Transform.__init__(self)
self.base = base
if nonpos == 'mask':
self._handle_nonpos = _mask_non_positives
else:
self._handle_nonpos = _clip_non_positives
def transform(self, a):
a = self._handle_nonpos(a * self.base)
if isinstance(a, MaskedArray):
return ma.log(a) / np.log(self.base)
return np.log(a) / np.log(self.base)
def inverted(self):
return LogScale.InvertedLogTransform(self.base)
class InvertedLogTransform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, base):
Transform.__init__(self)
self.base = base
def transform(self, a):
return ma.power(self.base, a) / self.base
def inverted(self):
return LogScale.LogTransform(self.base)
def __init__(self, axis, **kwargs):
"""
*basex*/*basey*:
The base of the logarithm
*nonposx*/*nonposy*: ['mask' | 'clip' ]
non-positive values in *x* or *y* can be masked as
invalid, or clipped to a very small positive number
*subsx*/*subsy*:
Where to place the subticks between each major tick.
Should be a sequence of integers. For example, in a log10
scale: ``[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]``
will place 10 logarithmically spaced minor ticks between
each major tick.
"""
if axis.axis_name == 'x':
base = kwargs.pop('basex', 10.0)
subs = kwargs.pop('subsx', None)
nonpos = kwargs.pop('nonposx', 'mask')
else:
base = kwargs.pop('basey', 10.0)
subs = kwargs.pop('subsy', None)
nonpos = kwargs.pop('nonposy', 'mask')
if nonpos not in ['mask', 'clip']:
raise ValueError("nonposx, nonposy kwarg must be 'mask' or 'clip'")
if base == 10.0:
self._transform = self.Log10Transform(nonpos)
elif base == 2.0:
self._transform = self.Log2Transform(nonpos)
elif base == np.e:
self._transform = self.NaturalLogTransform(nonpos)
else:
self._transform = self.LogTransform(base, nonpos)
self.base = base
self.subs = subs
def set_default_locators_and_formatters(self, axis):
"""
Set the locators and formatters to specialized versions for
log scaling.
"""
axis.set_major_locator(LogLocator(self.base))
axis.set_major_formatter(LogFormatterMathtext(self.base))
axis.set_minor_locator(LogLocator(self.base, self.subs))
axis.set_minor_formatter(NullFormatter())
def get_transform(self):
"""
Return a :class:`~matplotlib.transforms.Transform` instance
appropriate for the given logarithm base.
"""
return self._transform
def limit_range_for_scale(self, vmin, vmax, minpos):
"""
Limit the domain to positive values.
"""
return (vmin <= 0.0 and minpos or vmin,
vmax <= 0.0 and minpos or vmax)
class SymmetricalLogScale(ScaleBase):
"""
The symmetrical logarithmic scale is logarithmic in both the
positive and negative directions from the origin.
Since the values close to zero tend toward infinity, there is a
need to have a range around zero that is linear. The parameter
*linthresh* allows the user to specify the size of this range
(-*linthresh*, *linthresh*).
"""
name = 'symlog'
class SymmetricalLogTransform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, base, linthresh):
Transform.__init__(self)
self.base = base
self.linthresh = linthresh
self._log_base = np.log(base)
self._linadjust = (np.log(linthresh) / self._log_base) / linthresh
def transform(self, a):
a = np.asarray(a)
sign = np.sign(a)
masked = ma.masked_inside(a, -self.linthresh, self.linthresh, copy=False)
log = sign * ma.log(np.abs(masked)) / self._log_base
if masked.mask.any():
return np.asarray(ma.where(masked.mask,
a * self._linadjust,
log))
else:
return np.asarray(log)
def inverted(self):
return SymmetricalLogScale.InvertedSymmetricalLogTransform(self.base, self.linthresh)
class InvertedSymmetricalLogTransform(Transform):
input_dims = 1
output_dims = 1
is_separable = True
def __init__(self, base, linthresh):
Transform.__init__(self)
self.base = base
self.linthresh = linthresh
self._log_base = np.log(base)
self._log_linthresh = np.log(linthresh) / self._log_base
self._linadjust = linthresh / (np.log(linthresh) / self._log_base)
def transform(self, a):
a = np.asarray(a)
return np.where(a <= self._log_linthresh,
np.where(a >= -self._log_linthresh,
a * self._linadjust,
-(np.power(self.base, -a))),
np.power(self.base, a))
def inverted(self):
return SymmetricalLogScale.SymmetricalLogTransform(self.base)
def __init__(self, axis, **kwargs):
"""
*basex*/*basey*:
The base of the logarithm
*linthreshx*/*linthreshy*:
The range (-*x*, *x*) within which the plot is linear (to
avoid having the plot go to infinity around zero).
*subsx*/*subsy*:
Where to place the subticks between each major tick.
Should be a sequence of integers. For example, in a log10
scale: ``[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]``
will place 10 logarithmically spaced minor ticks between
each major tick.
"""
if axis.axis_name == 'x':
base = kwargs.pop('basex', 10.0)
linthresh = kwargs.pop('linthreshx', 2.0)
subs = kwargs.pop('subsx', None)
else:
base = kwargs.pop('basey', 10.0)
linthresh = kwargs.pop('linthreshy', 2.0)
subs = kwargs.pop('subsy', None)
self._transform = self.SymmetricalLogTransform(base, linthresh)
self.base = base
self.linthresh = linthresh
self.subs = subs
def set_default_locators_and_formatters(self, axis):
"""
Set the locators and formatters to specialized versions for
symmetrical log scaling.
"""
axis.set_major_locator(SymmetricalLogLocator(self.get_transform()))
axis.set_major_formatter(LogFormatterMathtext(self.base))
axis.set_minor_locator(SymmetricalLogLocator(self.get_transform(), self.subs))
axis.set_minor_formatter(NullFormatter())
def get_transform(self):
"""
Return a :class:`SymmetricalLogTransform` instance.
"""
return self._transform
_scale_mapping = {
'linear' : LinearScale,
'log' : LogScale,
'symlog' : SymmetricalLogScale
}
def get_scale_names():
names = _scale_mapping.keys()
names.sort()
return names
def scale_factory(scale, axis, **kwargs):
"""
Return a scale class by name.
ACCEPTS: [ %(names)s ]
"""
scale = scale.lower()
if scale is None:
scale = 'linear'
if scale not in _scale_mapping:
raise ValueError("Unknown scale type '%s'" % scale)
return _scale_mapping[scale](axis, **kwargs)
scale_factory.__doc__ = dedent(scale_factory.__doc__) % \
{'names': " | ".join(get_scale_names())}
def register_scale(scale_class):
"""
Register a new kind of scale.
*scale_class* must be a subclass of :class:`ScaleBase`.
"""
_scale_mapping[scale_class.name] = scale_class
def get_scale_docs():
"""
Helper function for generating docstrings related to scales.
"""
docs = []
for name in get_scale_names():
scale_class = _scale_mapping[name]
docs.append(" '%s'" % name)
docs.append("")
class_docs = dedent(scale_class.__init__.__doc__)
class_docs = "".join([" %s\n" %
x for x in class_docs.split("\n")])
docs.append(class_docs)
docs.append("")
return "\n".join(docs)
docstring.interpd.update(
scale = ' | '.join([repr(x) for x in get_scale_names()]),
scale_docs = get_scale_docs().strip(),
)