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dmcdougalldmcdougall
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Merge pull request #1671 from dmcdougall/feature_stack_base
Feature stack base
2 parents b7ff5d4 + 6b4678b commit daf551d

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‎CHANGELOG‎

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2013-01-07 Add framealpha keyword argument to legend - PO
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2013-01-16 Till Stensitzki added a baseline feature to stackplot
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2012-12-22 Added classes for interpolation within triangular grids
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(LinearTriInterpolator) and to find the triangles in which points
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lie (TrapezoidMapTriFinder) to matplotlib.tri module. - IMT

‎doc/users/whats_new.rst‎

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new in matplotlib-1.3
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=====================
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Baselines for stackplot
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-----------------------
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Till Stensitzki added non-zero baselines to :func:`~matplotlib.pyplot.stackplot`.
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They may be symmetric or weighted.
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.. plot:: mpl_examples/pylab_examples/stackplot_demo2.py
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Initialize a rotated rectangle
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------------------------------
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Damon McDougall extended the :class:`~matplotlib.patches.Rectangle` constructor

‎examples/pylab_examples/stackplot_demo2.py‎

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import numpy as np
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import matplotlib.pyplot as plt
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np.random.seed(0)
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def layers(n, m):
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"""
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Return *n* random Gaussian mixtures, each of length *m*.
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"""
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def bump(a):
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x = 1 / (.1 + np.random.random())
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y = 2 * np.random.random() - .5
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z = 10 / (.1 + np.random.random())
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for i in range(m):
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w = (i / float(m) - y) * z
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a[i] += x * np.exp(-w * w)
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a = np.zeros((m, n))
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for i in range(n):
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for j in range(5):
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bump(a[:, i])
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return a
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d = layers(3, 100)
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plt.subplots()
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plt.stackplot(range(100), d.T, baseline='wiggle')
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plt.show()

‎lib/matplotlib/stackplot.py‎

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Keyword arguments:
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*baseline* : ['zero', 'sym', 'wiggle', 'weighted_wiggle']
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Method used to calculate the baseline. 'zero' is just a
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simple stacked plot. 'sym' is symmetric around zero and
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is sometimes called `ThemeRiver`. 'wiggle' minimizes the
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sum of the squared slopes. 'weighted_wiggle' does the
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same but weights to account for size of each layer.
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It is also called `Streamgraph`-layout. More details
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can be found at http://www.leebyron.com/else/streamgraph/.
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*colors* : A list or tuple of colors. These will be cycled through and
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used to colour the stacked areas.
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All other keyword arguments are passed to
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if colors is not None:
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axes.set_color_cycle(colors)
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baseline = kwargs.pop('baseline', 'zero')
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# Assume data passed has not been 'stacked', so stack it here.
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y_stack = np.cumsum(y, axis=0)
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stack = np.cumsum(y, axis=0)
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r = []
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if baseline == 'zero':
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first_line = 0.
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elif baseline == 'sym':
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first_line = -np.sum(y, 0) * 0.5
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stack += first_line[None, :]
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elif baseline == 'wiggle':
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m = y.shape[0]
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first_line = (y * (m - 0.5 - np.arange(0, m)[:, None])).sum(0)
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first_line /= -m
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stack += first_line
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elif baseline == 'weighted_wiggle':
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m, n = y.shape
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center = np.zeros(n)
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total = np.sum(y, 0)
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increase = np.hstack((y[:, 0:1], np.diff(y)))
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below_size = total - stack
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below_size += 0.5 * y
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move_up = below_size / total
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move_up[:, 0] = 0.5
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center = (move_up - 0.5) * increase
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center = np.cumsum(center.sum(0))
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first_line = center - 0.5 * total
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stack += first_line
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else:
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errstr = "Baseline method %s not recognised. " % baseline
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errstr += "Expected 'zero', 'sym', 'wiggle' or 'weighted_wiggle'"
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raise ValueError(errstr)
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# Color between x = 0 and the first array.
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r.append(axes.fill_between(x, 0, y_stack[0, :],
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facecolor=axes._get_lines.color_cycle.next(), **kwargs))
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r.append(axes.fill_between(x, first_line, stack[0, :],
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facecolor=axes._get_lines.color_cycle.next(),
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**kwargs))
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# Color between array i-1 and array i
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for i in xrange(len(y) - 1):
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r.append(axes.fill_between(x, y_stack[i, :], y_stack[i + 1, :],
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facecolor=axes._get_lines.color_cycle.next(), **kwargs))
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color = axes._get_lines.color_cycle.next()
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r.append(axes.fill_between(x, stack[i, :], stack[i + 1, :],
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facecolor= color,
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**kwargs))
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return r

‎lib/matplotlib/tests/baseline_images/test_axes/stackplot_test_baseline.pdf‎

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‎lib/matplotlib/tests/baseline_images/test_axes/stackplot_test_baseline.png‎

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