@@ -334,24 +334,60 @@ class ColorConverter(object):
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def makeMappingArray (N , data , gamma = 1.0 ):
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- """Create an *N* -element 1-d lookup table
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-
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- *data* represented by a list of x,y0,y1 mapping correspondences.
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- Each element in this list represents how a value between 0 and 1
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- (inclusive) represented by x is mapped to a corresponding value
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- between 0 and 1 (inclusive). The two values of y are to allow
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- for discontinuous mapping functions (say as might be found in a
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- sawtooth) where y0 represents the value of y for values of x
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- <= to that given, and y1 is the value to be used for x > than
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- that given). The list must start with x=0, end with x=1, and
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- all values of x must be in increasing order. Values between
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- the given mapping points are determined by simple linear interpolation.
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-
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- Alternatively, data can be a function mapping values between 0 - 1
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- to 0 - 1.
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-
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- The function returns an array "result" where ``result[x*(N-1)]``
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- gives the closest value for values of x between 0 and 1.
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+ r"""Create an *N* -element 1-d lookup table.
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+
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+ This assumes a mapping :math:`f : [0, 1] \rightarrow [0, 1]`. The returned
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+ data is an array of N values :math:`y = f(x)` where x is sampled from
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+ [0, 1].
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+
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+ By default (*gamma* = 1) x is equidistantly sampled from [0, 1]. The
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+ *gamma* correction factor :math:`\gamma` distorts this equidistant
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+ sampling by :math:`x \rightarrow x^\gamma`.
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+
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+ Parameters
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+ ----------
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+ N : int
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+ The number of elements of the created lookup table.
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+ This must be N >= 1.
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+ data : Mx3 array-like or callable
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+ Defines the mapping :math:`f`.
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+
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+ If a Mx3 array-like, the rows define values (x, y0, y1). The x values
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+ must start with x=0, end with x=1, and all x values be in increasing
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+ order.
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+
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+ A value between :math:`x_i` and :math:`x_{i+1}` is mapped to the range
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+ :math:`y^1_{i-1} \ldots y^0_i` by linear interpolation.
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+
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+ For the simple case of a y-continuous mapping, y0 and y1 are identical.
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+
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+ The two values of y are to allow for discontinuous mapping functions.
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+ E.g. a sawtooth with a period of 0.2 and an amplitude of 1 would be::
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+
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+ [(0, 1, 0), (0.2, 1, 0), (0.4, 1, 0), ..., [(1, 1, 0)]
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+
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+ In the special case of ``N == 1``, by convention the returned value
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+ is y0 for x == 1.
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+
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+ If *data* is a callable, it must accept and return numpy arrays::
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+
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+ data(x : ndarray) -> ndarray
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+
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+ and map values between 0 - 1 to 0 - 1.
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+ gamma : float
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+ Gamma correction factor for input distribution x of the mapping.
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+
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+ See also https://en.wikipedia.org/wiki/Gamma_correction.
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+
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+ Returns
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+ -------
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+ lut : array
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+ The lookup table where ``lut[x * (N-1)]`` gives the closest value
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+ for values of x between 0 and 1.
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+
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+ Notes
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+ -----
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+ This function is internally used for `.LinearSegmentedColormaps`.
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"""
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if callable (data ):
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