Version 3.1.3
matplotlib
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Source code for matplotlib.scale

import inspect
import textwrap

import numpy as np
from numpy import ma

from matplotlib import cbook, docstring, rcParams
from matplotlib.ticker import (
    NullFormatter, ScalarFormatter, LogFormatterSciNotation, LogitFormatter,
    NullLocator, LogLocator, AutoLocator, AutoMinorLocator,
    SymmetricalLogLocator, LogitLocator)
from matplotlib.transforms import Transform, IdentityTransform


[docs]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` - :meth:`set_default_locators_and_formatters` And optionally: - :meth:`limit_range_for_scale` """ def __init__(self, axis, **kwargs): r""" Construct a new scale. Notes ----- The following note is for scale implementors. For back-compatibility reasons, scales take an `~matplotlib.axis.Axis` object as first argument. However, this argument should not be used: a single scale object should be usable by multiple `~matplotlib.axis.Axis`\es at the same time. """
[docs] def get_transform(self): """ Return the :class:`~matplotlib.transforms.Transform` object associated with this scale. """ raise NotImplementedError()
[docs] 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()
[docs] 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
[docs]class LinearScale(ScaleBase): """ The default linear scale. """ name = 'linear' def __init__(self, axis, **kwargs): # This method is present only to prevent inheritance of the base class' # constructor docstring, which would otherwise end up interpolated into # the docstring of Axis.set_scale. """ """ super().__init__(axis, **kwargs)
[docs] 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_formatter(NullFormatter()) # update the minor locator for x and y axis based on rcParams if (axis.axis_name == 'x' and rcParams['xtick.minor.visible'] or axis.axis_name == 'y' and rcParams['ytick.minor.visible']): axis.set_minor_locator(AutoMinorLocator()) else: axis.set_minor_locator(NullLocator())
[docs] def get_transform(self): """ The transform for linear scaling is just the :class:`~matplotlib.transforms.IdentityTransform`. """ return IdentityTransform()
[docs]class FuncTransform(Transform): """ A simple transform that takes and arbitrary function for the forward and inverse transform. """ input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, forward, inverse): """ Parameters ---------- forward : callable The forward function for the transform. This function must have an inverse and, for best behavior, be monotonic. It must have the signature:: def forward(values: array-like) -> array-like inverse : callable The inverse of the forward function. Signature as ``forward``. """ super().__init__() if callable(forward) and callable(inverse): self._forward = forward self._inverse = inverse else: raise ValueError('arguments to FuncTransform must ' 'be functions')
[docs] def transform_non_affine(self, values): return self._forward(values)
[docs] def inverted(self): return FuncTransform(self._inverse, self._forward)
[docs]class FuncScale(ScaleBase): """ Provide an arbitrary scale with user-supplied function for the axis. """ name = 'function' def __init__(self, axis, functions): """ Parameters ---------- axis: the axis for the scale functions : (callable, callable) two-tuple of the forward and inverse functions for the scale. The forward function must be monotonic. Both functions must have the signature:: def forward(values: array-like) -> array-like """ forward, inverse = functions transform = FuncTransform(forward, inverse) self._transform = transform
[docs] def get_transform(self): """ The transform for arbitrary scaling """ return self._transform
[docs] def set_default_locators_and_formatters(self, axis): """ Set the locators and formatters to the same defaults as the linear scale. """ axis.set_major_locator(AutoLocator()) axis.set_major_formatter(ScalarFormatter()) axis.set_minor_formatter(NullFormatter()) # update the minor locator for x and y axis based on rcParams if (axis.axis_name == 'x' and rcParams['xtick.minor.visible'] or axis.axis_name == 'y' and rcParams['ytick.minor.visible']): axis.set_minor_locator(AutoMinorLocator()) else: axis.set_minor_locator(NullLocator())
[docs]@cbook.deprecated("3.1", alternative="LogTransform") class LogTransformBase(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, nonpos='clip'): Transform.__init__(self) self._clip = {"clip": True, "mask": False}[nonpos]
[docs] def transform_non_affine(self, a): return LogTransform.transform_non_affine(self, a)
def __str__(self): return "{}({!r})".format( type(self).__name__, "clip" if self._clip else "mask")
[docs]@cbook.deprecated("3.1", alternative="InvertedLogTransform") class InvertedLogTransformBase(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True
[docs] def transform_non_affine(self, a): return ma.power(self.base, a)
def __str__(self): return "{}()".format(type(self).__name__)
[docs]@cbook.deprecated("3.1", alternative="LogTransform") class Log10Transform(LogTransformBase): base = 10.0
[docs] def inverted(self): return InvertedLog10Transform()
[docs]@cbook.deprecated("3.1", alternative="InvertedLogTransform") class InvertedLog10Transform(InvertedLogTransformBase): base = 10.0
[docs] def inverted(self): return Log10Transform()
[docs]@cbook.deprecated("3.1", alternative="LogTransform") class Log2Transform(LogTransformBase): base = 2.0
[docs] def inverted(self): return InvertedLog2Transform()
[docs]@cbook.deprecated("3.1", alternative="InvertedLogTransform") class InvertedLog2Transform(InvertedLogTransformBase): base = 2.0
[docs] def inverted(self): return Log2Transform()
[docs]@cbook.deprecated("3.1", alternative="LogTransform") class NaturalLogTransform(LogTransformBase): base = np.e
[docs] def inverted(self): return InvertedNaturalLogTransform()
[docs]@cbook.deprecated("3.1", alternative="InvertedLogTransform") class InvertedNaturalLogTransform(InvertedLogTransformBase): base = np.e
[docs] def inverted(self): return NaturalLogTransform()
[docs]class LogTransform(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, base, nonpos='clip'): Transform.__init__(self) self.base = base self._clip = {"clip": True, "mask": False}[nonpos] def __str__(self): return "{}(base={}, nonpos={!r})".format( type(self).__name__, self.base, "clip" if self._clip else "mask")
[docs] def transform_non_affine(self, a): # Ignore invalid values due to nans being passed to the transform. with np.errstate(divide="ignore", invalid="ignore"): log = {np.e: np.log, 2: np.log2, 10: np.log10}.get(self.base) if log: # If possible, do everything in a single call to Numpy. out = log(a) else: out = np.log(a) out /= np.log(self.base) if self._clip: # SVG spec says that conforming viewers must support values up # to 3.4e38 (C float); however experiments suggest that # Inkscape (which uses cairo for rendering) runs into cairo's # 24-bit limit (which is apparently shared by Agg). # Ghostscript (used for pdf rendering appears to overflow even # earlier, with the max value around 2 ** 15 for the tests to # pass. On the other hand, in practice, we want to clip beyond # np.log10(np.nextafter(0, 1)) ~ -323 # so 1000 seems safe. out[a <= 0] = -1000 return out
[docs] def inverted(self): return InvertedLogTransform(self.base)
[docs]class InvertedLogTransform(InvertedLogTransformBase): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, base): Transform.__init__(self) self.base = base def __str__(self): return "{}(base={})".format(type(self).__name__, self.base)
[docs] def transform_non_affine(self, a): return ma.power(self.base, a)
[docs] def inverted(self): return LogTransform(self.base)
[docs]class LogScale(ScaleBase): """ A standard logarithmic scale. Care is taken to only plot positive values. """ name = 'log' # compatibility shim LogTransformBase = LogTransformBase Log10Transform = Log10Transform InvertedLog10Transform = InvertedLog10Transform Log2Transform = Log2Transform InvertedLog2Transform = InvertedLog2Transform NaturalLogTransform = NaturalLogTransform InvertedNaturalLogTransform = InvertedNaturalLogTransform LogTransform = LogTransform InvertedLogTransform = InvertedLogTransform 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: ``[2, 3, 4, 5, 6, 7, 8, 9]`` will place 8 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', 'clip') cbook._check_in_list(['mask', 'clip'], nonposx=nonpos) else: base = kwargs.pop('basey', 10.0) subs = kwargs.pop('subsy', None) nonpos = kwargs.pop('nonposy', 'clip') cbook._check_in_list(['mask', 'clip'], nonposy=nonpos) if len(kwargs): raise ValueError(("provided too many kwargs, can only pass " "{'basex', 'subsx', nonposx'} or " "{'basey', 'subsy', nonposy'}. You passed ") + "{!r}".format(kwargs)) if base <= 0 or base == 1: raise ValueError('The log base cannot be <= 0 or == 1') self._transform = self.LogTransform(base, nonpos) self.subs = subs @property def base(self): return self._transform.base
[docs] 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(LogFormatterSciNotation(self.base)) axis.set_minor_locator(LogLocator(self.base, self.subs)) axis.set_minor_formatter( LogFormatterSciNotation(self.base, labelOnlyBase=(self.subs is not None)))
[docs] def get_transform(self): """ Return a :class:`~matplotlib.transforms.Transform` instance appropriate for the given logarithm base. """ return self._transform
[docs] def limit_range_for_scale(self, vmin, vmax, minpos): """ Limit the domain to positive values. """ if not np.isfinite(minpos): minpos = 1e-300 # This value should rarely if ever # end up with a visible effect. return (minpos if vmin <= 0 else vmin, minpos if vmax <= 0 else vmax)
[docs]class FuncScaleLog(LogScale): """ Provide an arbitrary scale with user-supplied function for the axis and then put on a logarithmic axes. """ name = 'functionlog' def __init__(self, axis, functions, base=10): """ Parameters ---------- axis: the axis for the scale functions : (callable, callable) two-tuple of the forward and inverse functions for the scale. The forward function must be monotonic. Both functions must have the signature:: def forward(values: array-like) -> array-like base : float logarithmic base of the scale (default = 10) """ forward, inverse = functions self.subs = None self._transform = FuncTransform(forward, inverse) + LogTransform(base) @property def base(self): return self._transform._b.base # Base of the LogTransform.
[docs] def get_transform(self): """ The transform for arbitrary scaling """ return self._transform
[docs]class SymmetricalLogTransform(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, base, linthresh, linscale): Transform.__init__(self) self.base = base self.linthresh = linthresh self.linscale = linscale self._linscale_adj = (linscale / (1.0 - self.base ** -1)) self._log_base = np.log(base)
[docs] def transform_non_affine(self, a): abs_a = np.abs(a) with np.errstate(divide="ignore", invalid="ignore"): out = np.sign(a) * self.linthresh * ( self._linscale_adj + np.log(abs_a / self.linthresh) / self._log_base) inside = abs_a <= self.linthresh out[inside] = a[inside] * self._linscale_adj return out
[docs] def inverted(self): return InvertedSymmetricalLogTransform(self.base, self.linthresh, self.linscale)
[docs]class InvertedSymmetricalLogTransform(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, base, linthresh, linscale): Transform.__init__(self) symlog = SymmetricalLogTransform(base, linthresh, linscale) self.base = base self.linthresh = linthresh self.invlinthresh = symlog.transform(linthresh) self.linscale = linscale self._linscale_adj = (linscale / (1.0 - self.base ** -1))
[docs] def transform_non_affine(self, a): abs_a = np.abs(a) with np.errstate(divide="ignore", invalid="ignore"): out = np.sign(a) * self.linthresh * ( np.power(self.base, abs_a / self.linthresh - self._linscale_adj)) inside = abs_a <= self.invlinthresh out[inside] = a[inside] / self._linscale_adj return out
[docs] def inverted(self): return SymmetricalLogTransform(self.base, self.linthresh, self.linscale)
[docs]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*). Parameters ---------- basex, basey : float The base of the logarithm. Defaults to 10. linthreshx, linthreshy : float Defines the range ``(-x, x)``, within which the plot is linear. This avoids having the plot go to infinity around zero. Defaults to 2. subsx, subsy : sequence of int Where to place the subticks between each major tick. For example, in a log10 scale: ``[2, 3, 4, 5, 6, 7, 8, 9]`` will place 8 logarithmically spaced minor ticks between each major tick. linscalex, linscaley : float, optional This allows the linear range ``(-linthresh, linthresh)`` to be stretched relative to the logarithmic range. Its value is the number of decades to use for each half of the linear range. For example, when *linscale* == 1.0 (the default), the space used for the positive and negative halves of the linear range will be equal to one decade in the logarithmic range. """ name = 'symlog' # compatibility shim SymmetricalLogTransform = SymmetricalLogTransform InvertedSymmetricalLogTransform = InvertedSymmetricalLogTransform def __init__(self, axis, **kwargs): if axis.axis_name == 'x': base = kwargs.pop('basex', 10.0) linthresh = kwargs.pop('linthreshx', 2.0) subs = kwargs.pop('subsx', None) linscale = kwargs.pop('linscalex', 1.0) else: base = kwargs.pop('basey', 10.0) linthresh = kwargs.pop('linthreshy', 2.0) subs = kwargs.pop('subsy', None) linscale = kwargs.pop('linscaley', 1.0) if base <= 1.0: raise ValueError("'basex/basey' must be larger than 1") if linthresh <= 0.0: raise ValueError("'linthreshx/linthreshy' must be positive") if linscale <= 0.0: raise ValueError("'linscalex/linthreshy' must be positive") self._transform = self.SymmetricalLogTransform(base, linthresh, linscale) self.base = base self.linthresh = linthresh self.linscale = linscale self.subs = subs
[docs] 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(LogFormatterSciNotation(self.base)) axis.set_minor_locator(SymmetricalLogLocator(self.get_transform(), self.subs)) axis.set_minor_formatter(NullFormatter())
[docs] def get_transform(self): """ Return a :class:`SymmetricalLogTransform` instance. """ return self._transform
[docs]class LogitTransform(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, nonpos='mask'): Transform.__init__(self) self._nonpos = nonpos self._clip = {"clip": True, "mask": False}[nonpos]
[docs] def transform_non_affine(self, a): """logit transform (base 10), masked or clipped""" with np.errstate(divide="ignore", invalid="ignore"): out = np.log10(a / (1 - a)) if self._clip: # See LogTransform for choice of clip value. out[a <= 0] = -1000 out[1 <= a] = 1000 return out
[docs] def inverted(self): return LogisticTransform(self._nonpos)
def __str__(self): return "{}({!r})".format(type(self).__name__, "clip" if self._clip else "mask")
[docs]class LogisticTransform(Transform): input_dims = 1 output_dims = 1 is_separable = True has_inverse = True def __init__(self, nonpos='mask'): Transform.__init__(self) self._nonpos = nonpos
[docs] def transform_non_affine(self, a): """logistic transform (base 10)""" return 1.0 / (1 + 10**(-a))
[docs] def inverted(self): return LogitTransform(self._nonpos)
def __str__(self): return "{}({!r})".format(type(self).__name__, self._nonpos)
[docs]class LogitScale(ScaleBase): """ Logit scale for data between zero and one, both excluded. This scale is similar to a log scale close to zero and to one, and almost linear around 0.5. It maps the interval ]0, 1[ onto ]-infty, +infty[. """ name = 'logit' def __init__(self, axis, nonpos='mask'): """ *nonpos*: {'mask', 'clip'} values beyond ]0, 1[ can be masked as invalid, or clipped to a number very close to 0 or 1 """ cbook._check_in_list(['mask', 'clip'], nonpos=nonpos) self._transform = LogitTransform(nonpos)
[docs] def get_transform(self): """ Return a :class:`LogitTransform` instance. """ return self._transform
[docs] def set_default_locators_and_formatters(self, axis): # ..., 0.01, 0.1, 0.5, 0.9, 0.99, ... axis.set_major_locator(LogitLocator()) axis.set_major_formatter(LogitFormatter()) axis.set_minor_locator(LogitLocator(minor=True)) axis.set_minor_formatter(LogitFormatter())
[docs] def limit_range_for_scale(self, vmin, vmax, minpos): """ Limit the domain to values between 0 and 1 (excluded). """ if not np.isfinite(minpos): minpos = 1e-7 # This value should rarely if ever # end up with a visible effect. return (minpos if vmin <= 0 else vmin, 1 - minpos if vmax >= 1 else vmax)
_scale_mapping = { 'linear': LinearScale, 'log': LogScale, 'symlog': SymmetricalLogScale, 'logit': LogitScale, 'function': FuncScale, 'functionlog': FuncScaleLog, }
[docs]def get_scale_names(): return sorted(_scale_mapping)
[docs]def scale_factory(scale, axis, **kwargs): """ Return a scale class by name. Parameters ---------- scale : {%(names)s} axis : Axis """ scale = scale.lower() if scale not in _scale_mapping: raise ValueError("Unknown scale type '%s'" % scale) return _scale_mapping[scale](axis, **kwargs)
if scale_factory.__doc__: scale_factory.__doc__ = scale_factory.__doc__ % { "names": ", ".join(get_scale_names())}
[docs]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
[docs]@cbook.deprecated( '3.1', message='get_scale_docs() is considered private API since ' '3.1 and will be removed from the public API in 3.3.') def get_scale_docs(): """ Helper function for generating docstrings related to scales. """ return _get_scale_docs()
def _get_scale_docs(): """ Helper function for generating docstrings related to scales. """ docs = [] for name, scale_class in _scale_mapping.items(): docs.extend([ f" {name!r}", "", textwrap.indent(inspect.getdoc(scale_class.__init__), " " * 8), "" ]) return "\n".join(docs) docstring.interpd.update( scale=' | '.join([repr(x) for x in get_scale_names()]), scale_docs=_get_scale_docs().rstrip(), )