Choosing the order of bars in the Bokeh histogram

Question

As part of an attempt to learn how to use Bokeh, I am trying to create a simple histogram. I skip labels in a specific order (days of the week), and Bokeh seems to sort them alphabetically. How can I display strings in the order of the source list?

from bokeh.plotting import show from bokeh.io import output_notebook from bokeh.charts import Bar from collections import OrderedDict import calendar output_notebook() data = OrderedDict() data['values'] = [2,3,4,5,6,7,8] #values only ascending to make correct graph clear data['days'] = [calendar.day_name[i-1] for i in range(7)] p = Bar(data, label='days', values='values', title='OrderedDict Input',xlabel="Day", ylabel="Value") show(p) 

Result generated

Answer 1

I'm not a big fan of high-level charts like Bar charts. They are not very customizable. Building them "manually" is often easier - and not much longer. This is what I would do with rects:

 from bokeh.plotting import show,figure from bokeh.io import output_notebook from bokeh.models import Range1d import calendar output_notebook() order = range(1,8) values=[2,3,4,5,6,7,8] days = [calendar.day_name[i-1] for i in order] yr = Range1d(0,max(values)) p = figure(x_range=days, y_range=yr) p.rect(order, [val/2.0 for val in values] , width=0.5, height=values, color = "#ff1200") show(p) 

Hope this helps, t.

Edit:

This is now even easier with vbar :

 from bokeh.plotting import figure from bokeh.io import output_file, show import calendar values = [2,3,4,5,6,7,8] days = [calendar.day_name[i-1] for i in range(1,8)] p = figure(x_range=days) p.vbar(x=days, width=0.5, top=values, color = "#ff1200") output_file('foo.html') show(p) 

which gives:

Answer 2

Here's how to keep the original label order in your example using the Charts interface tested with Bokeh 0.11.1.

 from bokeh.plotting import show from bokeh.io import output_notebook from bokeh.charts import Bar from collections import OrderedDict import calendar from bokeh.charts.attributes import CatAttr output_notebook() data = OrderedDict() data['values'] = [2,3,4,5,6,7,8] #values only ascending to make correct graph clear data['days'] = [calendar.day_name[i-1] for i in range(7)] p = Bar(data, label=CatAttr(columns=['days'], sort=False), values='values',title='OrderedDict Input',xlabel="Day", ylabel="Value") show(p) 

Answer 3

In general, with any plot, you can specify the core of x (or y) explicitly. tk answer is useful if you want to completely ignore the Bar chart class (which is not the worst idea in the world for these reasons). user666 answer is useful if your data columns are already ordered the way you want. Otherwise, you can specify the order yourself:

Week Starts Sunday:

 from bokeh.models import FactorRange ... p.x_range = FactorRange(factors=data['days']) 

Week Starts Monday:

 p.x_range = FactorRange(factors=data['days'][1:] + [data['days'][0]]) 

Answer 4

This is a comment related to user666's answer (I do not have enough credits to add comments.)

I don’t think that using OrderedDict helps here, because it only remembers the order in which the keys were inserted (that is, the "values" precede the "days"), and not the order of the sequences that are the values ​​associated with these keys.

FYI also discusses this issue on the GitHub bokeh site here: https://github.com/bokeh/bokeh/issues/2924 and here: https://github.com/bokeh/bokeh/pull/3623