I am trying to control the colour for each bar and each bar segment, in a Chaco stacked bar plot.
For example, running Chaco's stacked bar plot example gives,
How do I turn it into this monstrosity?
I can see Chaco has ColourMapped Scatter Plot which allows control over each point. I need this behavior but with bar plots. Is there a quick way of doing this?
Here is the demo. code to generate the default Chaco Stacked Bar Plot
"""
Simple example of a stacked bar chart
"""
# Major library imports
import numpy
# Enthought library imports
from enable.api import ComponentEditor
from traits.api import HasTraits, Instance
from traitsui.api import UItem, View
# Chaco imports
from chaco.api import LabelAxis, Plot, ArrayPlotData, ArrayDataSource
class PlotExample(HasTraits):
plot = Instance(Plot)
def _plot_default(self):
index = numpy.array([1, 2, 3, 4, 5])
series_a, series_b, series_c = (index * 10, index * 5, index * 2)
# Stack them up
series_c = series_c + series_b + series_a
series_b = series_b + series_a
plot_data = ArrayPlotData(index=index)
plot_data.set_data("series_a", series_a)
plot_data.set_data("series_b", series_b)
plot_data.set_data("series_c", series_c)
plot = Plot(plot_data)
plot.plot(("index", "series_a"), type="bar", bar_width=0.8, color="auto")
plot.plot(
("index", "series_b"),
type="bar",
bar_width=0.8,
color="auto",
starting_value=ArrayDataSource(series_a),
)
plot.plot(
("index", "series_c"),
type="bar",
bar_width=0.8,
color="auto",
starting_value=ArrayDataSource(series_b),
)
# set the plot's value range to 0, otherwise it may pad too much
plot.value_range.low = 0
# replace the index values with some nicer labels
label_axis = LabelAxis(
plot,
orientation="bottom",
title="Months",
positions=list(range(1, 10)),
labels=["jan", "feb", "march", "april", "may"],
small_haxis_style=True,
)
plot.underlays.remove(plot.index_axis)
plot.index_axis = label_axis
plot.underlays.append(label_axis)
return plot
traits_view = View(
UItem("plot", editor=ComponentEditor()), width=400, height=400, resizable=True,
)
demo = PlotExample()
if __name__ == "__main__":
demo.configure_traits()
I would approach this problem by making a separate bar plot renderer for each segment in the stacked bar chart. Something like this should do the trick (sorry for the very verbose for
statements):
"""
Simple example of a stacked bar chart
"""
# Major library imports
import numpy
# Enthought library imports
from enable.api import ComponentEditor
from traits.api import HasTraits, Instance
from traitsui.api import UItem, View
# Chaco imports
from chaco.api import LabelAxis, Plot, ArrayPlotData, ArrayDataSource
class PlotExample(HasTraits):
plot = Instance(Plot)
def _plot_default(self):
index = numpy.array([1, 2, 3, 4, 5])
series_a, series_b, series_c = (index * 10, index * 5, index * 2)
# Stack them up
series_c = series_c + series_b + series_a
series_b = series_b + series_a
plot_data = ArrayPlotData()
for i, (index_val, series_a_val, series_b_val, series_c_val) in enumerate(zip(
index, series_a, series_b, series_c
)):
plot_data.set_data(f"index_{i}", [index_val])
plot_data.set_data(f"series_a_{i}", [series_a_val])
plot_data.set_data(f"series_b_{i}", [series_b_val])
plot_data.set_data(f"series_c_{i}", [series_c_val])
plot = Plot(plot_data)
for i, (index_val, series_a_val, series_b_val, series_c_val) in enumerate(zip(
index, series_a, series_b, series_c
)):
plot.plot(
(f"index_{i}", f"series_a_{i}"),
type="bar",
bar_width=0.8,
color="auto",
)
plot.plot(
(f"index_{i}", f"series_b_{i}"),
type="bar",
bar_width=0.8,
color="auto",
starting_value=ArrayDataSource([series_a_val]),
)
plot.plot(
(f"index_{i}", f"series_c_{i}"),
type="bar",
bar_width=0.8,
color="auto",
starting_value=ArrayDataSource([series_b_val]),
)
# set the plot's value range to 0, otherwise it may pad too much
plot.value_range.low = 0
# replace the index values with some nicer labels
label_axis = LabelAxis(
plot,
orientation="bottom",
title="Months",
positions=list(range(1, 10)),
labels=["jan", "feb", "march", "april", "may"],
small_haxis_style=True,
)
plot.underlays.remove(plot.index_axis)
plot.index_axis = label_axis
plot.underlays.append(label_axis)
return plot
traits_view = View(
UItem("plot", editor=ComponentEditor()), width=400, height=400, resizable=True,
)
demo = PlotExample()
if __name__ == "__main__":
demo.configure_traits()