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"""
This module provides a large set of colormaps, functions for
registering new colormaps and for getting a colormap by name,
and a mixin class for adding color mapping functionality.
"""
from __future__ import print_function
import os
import numpy as np
from numpy import ma
import matplotlib as mpl
import matplotlib.colors as colors
import matplotlib.cbook as cbook
from matplotlib._cm import datad
from matplotlib._cm import cubehelix
cmap_d = dict()
# reverse all the colormaps.
# reversed colormaps have '_r' appended to the name.
def _reverser(f):
def freversed(x):
return f(1-x)
return freversed
def revcmap(data):
"""Can only handle specification *data* in dictionary format."""
data_r = {}
for key, val in data.iteritems():
if callable(val):
valnew = _reverser(val)
# This doesn't work: lambda x: val(1-x)
# The same "val" (the first one) is used
# each time, so the colors are identical
# and the result is shades of gray.
else:
# Flip x and exchange the y values facing x = 0 and x = 1.
valnew = [(1.0 - x, y1, y0) for x, y0, y1 in reversed(val)]
data_r[key] = valnew
return data_r
def _reverse_cmap_spec(spec):
"""Reverses cmap specification *spec*, can handle both dict and tuple
type specs."""
if 'red' in spec:
return revcmap(spec)
else:
revspec = list(reversed(spec))
if len(revspec[0]) == 2: # e.g., (1, (1.0, 0.0, 1.0))
revspec = [(1.0 - a, b) for a, b in revspec]
return revspec
def _generate_cmap(name, lutsize):
"""Generates the requested cmap from it's name *name*. The lut size is
*lutsize*."""
spec = datad[name]
# Generate the colormap object.
if 'red' in spec:
return colors.LinearSegmentedColormap(name, spec, lutsize)
else:
return colors.LinearSegmentedColormap.from_list(spec, spec, lutsize)
LUTSIZE = mpl.rcParams['image.lut']
_cmapnames = datad.keys() # need this list because datad is changed in loop
# Generate the reversed specifications ...
for cmapname in _cmapnames:
spec = datad[cmapname]
spec_reversed = _reverse_cmap_spec(spec)
datad[cmapname + '_r'] = spec_reversed
# Precache the cmaps with ``lutsize = LUTSIZE`` ...
# Use datad.keys() to also add the reversed ones added in the section above:
for cmapname in datad.iterkeys():
cmap_d[cmapname] = _generate_cmap(cmapname, LUTSIZE)
locals().update(cmap_d)
# Continue with definitions ...
def register_cmap(name=None, cmap=None, data=None, lut=None):
"""
Add a colormap to the set recognized by :func:`get_cmap`.
It can be used in two ways::
register_cmap(name='swirly', cmap=swirly_cmap)
register_cmap(name='choppy', data=choppydata, lut=128)
In the first case, *cmap* must be a :class:`colors.Colormap`
instance. The *name* is optional; if absent, the name will
be the :attr:`name` attribute of the *cmap*.
In the second case, the three arguments are passed to
the :class:`colors.LinearSegmentedColormap` initializer,
and the resulting colormap is registered.
"""
if name is None:
try:
name = cmap.name
except AttributeError:
raise ValueError("Arguments must include a name or a Colormap")
if not cbook.is_string_like(name):
raise ValueError("Colormap name must be a string")
if isinstance(cmap, colors.Colormap):
cmap_d[name] = cmap
return
# For the remainder, let exceptions propagate.
if lut is None:
lut = mpl.rcParams['image.lut']
cmap = colors.LinearSegmentedColormap(name, data, lut)
cmap_d[name] = cmap
def get_cmap(name=None, lut=None):
"""
Get a colormap instance, defaulting to rc values if *name* is None.
Colormaps added with :func:`register_cmap` take precedence over
builtin colormaps.
If *name* is a :class:`colors.Colormap` instance, it will be
returned.
If *lut* is not None it must be an integer giving the number of
entries desired in the lookup table, and *name* must be a
standard mpl colormap name with a corresponding data dictionary
in *datad*.
"""
if name is None:
name = mpl.rcParams['image.cmap']
if isinstance(name, colors.Colormap):
return name
if name in cmap_d:
if lut is None:
return cmap_d[name]
elif name in datad:
return _generate_cmap(name, lut)
else:
raise ValueError("Colormap %s is not recognized" % name)
class ScalarMappable:
"""
This is a mixin class to support scalar -> RGBA mapping. Handles
normalization and colormapping
"""
def __init__(self, norm=None, cmap=None):
"""
*norm* is an instance of :class:`colors.Normalize` or one of
its subclasses, used to map luminance to 0-1. *cmap* is a
:mod:`cm` colormap instance, for example :data:`cm.jet`
"""
self.callbacksSM = cbook.CallbackRegistry()
if cmap is None: cmap = get_cmap()
if norm is None: norm = colors.Normalize()
self._A = None
self.norm = norm
self.cmap = get_cmap(cmap)
self.colorbar = None
self.update_dict = {'array':False}
def set_colorbar(self, im, ax):
'set the colorbar image and axes associated with mappable'
self.colorbar = im, ax
def to_rgba(self, x, alpha=None, bytes=False):
"""
Return a normalized rgba array corresponding to *x*.
In the normal case, *x* is a 1-D or 2-D sequence of scalars, and
the corresponding ndarray of rgba values will be returned,
based on the norm and colormap set for this ScalarMappable.
There is one special case, for handling images that are already
rgb or rgba, such as might have been read from an image file.
If *x* is an ndarray with 3 dimensions,
and the last dimension is either 3 or 4, then it will be
treated as an rgb or rgba array, and no mapping will be done.
If the last dimension is 3, the *alpha* kwarg (defaulting to 1)
will be used to fill in the transparency. If the last dimension
is 4, the *alpha* kwarg is ignored; it does not
replace the pre-existing alpha. A ValueError will be raised
if the third dimension is other than 3 or 4.
In either case, if *bytes* is *False* (default), the rgba
array will be floats in the 0-1 range; if it is *True*,
the returned rgba array will be uint8 in the 0 to 255 range.
Note: this method assumes the input is well-behaved; it does
not check for anomalies such as *x* being a masked rgba
array, or being an integer type other than uint8, or being
a floating point rgba array with values outside the 0-1 range.
"""
# First check for special case, image input:
try:
if x.ndim == 3:
if x.shape[2] == 3:
if alpha is None:
alpha = 1
if x.dtype == np.uint8:
alpha = np.uint8(alpha * 255)
m, n = x.shape[:2]
xx = np.empty(shape=(m,n,4), dtype = x.dtype)
xx[:,:,:3] = x
xx[:,:,3] = alpha
elif x.shape[2] == 4:
xx = x
else:
raise ValueError("third dimension must be 3 or 4")
if bytes and xx.dtype != np.uint8:
xx = (xx * 255).astype(np.uint8)
if not bytes and xx.dtype == np.uint8:
xx = xx.astype(float) / 255
return xx
except AttributeError:
# e.g., x is not an ndarray; so try mapping it
pass
# This is the normal case, mapping a scalar array:
x = ma.asarray(x)
x = self.norm(x)
x = self.cmap(x, alpha=alpha, bytes=bytes)
return x
def set_array(self, A):
'Set the image array from numpy array *A*'
self._A = A
self.update_dict['array'] = True
def get_array(self):
'Return the array'
return self._A
def get_cmap(self):
'return the colormap'
return self.cmap
def get_clim(self):
'return the min, max of the color limits for image scaling'
return self.norm.vmin, self.norm.vmax
def set_clim(self, vmin=None, vmax=None):
"""
set the norm limits for image scaling; if *vmin* is a length2
sequence, interpret it as ``(vmin, vmax)`` which is used to
support setp
ACCEPTS: a length 2 sequence of floats
"""
if (vmin is not None and vmax is None and
cbook.iterable(vmin) and len(vmin)==2):
vmin, vmax = vmin
if vmin is not None: self.norm.vmin = vmin
if vmax is not None: self.norm.vmax = vmax
self.changed()
def set_cmap(self, cmap):
"""
set the colormap for luminance data
ACCEPTS: a colormap or registered colormap name
"""
cmap = get_cmap(cmap)
self.cmap = cmap
self.changed()
def set_norm(self, norm):
'set the normalization instance'
if norm is None: norm = colors.Normalize()
self.norm = norm
self.changed()
def autoscale(self):
"""
Autoscale the scalar limits on the norm instance using the
current array
"""
if self._A is None:
raise TypeError('You must first set_array for mappable')
self.norm.autoscale(self._A)
self.changed()
def autoscale_None(self):
"""
Autoscale the scalar limits on the norm instance using the
current array, changing only limits that are None
"""
if self._A is None:
raise TypeError('You must first set_array for mappable')
self.norm.autoscale_None(self._A)
self.changed()
def add_checker(self, checker):
"""
Add an entry to a dictionary of boolean flags
that are set to True when the mappable is changed.
"""
self.update_dict[checker] = False
def check_update(self, checker):
"""
If mappable has changed since the last check,
return True; else return False
"""
if self.update_dict[checker]:
self.update_dict[checker] = False
return True
return False
def changed(self):
"""
Call this whenever the mappable is changed to notify all the
callbackSM listeners to the 'changed' signal
"""
self.callbacksSM.process('changed', self)
for key in self.update_dict:
self.update_dict[key] = True
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