Change label ordering in bokeh heatmap

Question

From the bokeh examples

from bokeh.charts import HeatMap, output_file, show

data = {'fruit': ['apples']*3 + ['bananas']*3 + ['pears']*3,
        'fruit_count': [4, 5, 8, 1, 2, 4, 6, 5, 4],
        'sample': [1, 2, 3]*3}

hm = HeatMap(data, x='fruit', y='sample', values='fruit_count',
             title='Fruits', stat=None)

show(hm)

is there a workaround for changing the order in which the labels are displayed? For example, if I wanted to show pears first?

Answer 1

First, you should not use bokeh.charts . It was deprecated, and has been removed from core Bokeh to a separate bkcharts repo. It is completely unsupported and unmaintained . It will not see any new features, bugfixes, improvements, or documentation. It is a dead end.

---

There are two good options to create this chart:

1) Use the stable and well-supported bokeh.plotting API. This is slightly more verbose, but gives you explicit control over everything, eg the order if the categories. In the code below these are specified as x_range and y_range values to figure :

from bokeh.io import output_file, show
from bokeh.models import ColumnDataSource, LinearColorMapper
from bokeh.palettes import Spectral9
from bokeh.plotting import figure
from bokeh.transform import transform

source = ColumnDataSource(data={
    'fruit': ['apples']*3 + ['bananas']*3 + ['pears']*3,
    'fruit_count': [4, 5, 8, 1, 2, 4, 6, 5, 4],
    'sample': ['1', '2', '3']*3,
})

mapper = LinearColorMapper(palette=Spectral9, low=0, high=8)

p = figure(x_range=['apples', 'bananas', 'pears'], y_range=['1', '2', '3'], 
           title='Fruits')
p.rect(x='fruit', y='sample', width=1, height=1, line_color=None,
       fill_color=transform('fruit_count', mapper), source=source)

show(p)

This yields the output below:

You can find much more information (as well as live examples) about categorical data with Bokeh in the Handling Categorical Data sections of the User's Guide.

2) Look into HoloViews , which is a very high level API on top of Bokeh that is actively maintained by a team, and endorsed by the Bokeh team as well. A simple HeatMap in HoloViews is typically a one-liner as with bokeh.charts .