Bokeh secondary y range affecting primary y range - python-3.x

Question

I'm working on building a Bokeh plot using bokeh.plotting. I have two series with a shared index that I want to plot two vertical bars for. When I use a single bar everything works fine, but when I add a second y range and the second bar it seems to be impacting the primary y range (changes the vales from 0 to 4), and my second vbar() overlays the first. Any assistance on why the bars overlap instead of being side by side and why the second series/yaxis seems to impact the first even though they are separate would be appreciated.
import pandas as pd
import bokeh.plotting as bp
from bokeh.models import NumeralTickFormatter, HoverTool, Range1d, LinearAxis
df_x_series = ['a','b','c']
fig = bp.figure(title='WIP',x_range=df_x_series,plot_width=1200,plot_height=600,toolbar_location='below',toolbar_sticky=False,tools=['reset','save'],active_scroll=None,active_drag=None,active_tap=None)
fig.title.align= 'center'
fig.extra_y_ranges = {'c_count':Range1d(start=0, end=10)}
fig.add_layout(LinearAxis(y_range_name='c_count'), 'right')
fig.vbar(bottom=0, top=[1,2,3], x=['a','b','c'], color='blue', legend='Amt', width=0.3, alpha=0.5)
fig.vbar(bottom=0, top=[5,7,8], x=['a','b','c'], color='green', legend='Ct', width=0.3, alpha=0.8, y_range_name='c_count')
fig.yaxis[0].formatter = NumeralTickFormatter(format='0.0')
bp.output_file('bar.html')
bp.show(fig)

Answer 1

Here's the plot I believe you want:
And here's the code:
import bokeh.plotting as bp
from bokeh.models import NumeralTickFormatter, Range1d, LinearAxis
df_x_series = ['a', 'b', 'c']
fig = bp.figure(
title='WIP',
x_range=df_x_series,
y_range=Range1d(start=0, end=4),
plot_width=1200, plot_height=600,
toolbar_location='below',
toolbar_sticky=False,
tools=['reset', 'save'],
active_scroll=None, active_drag=None, active_tap=None
)
fig.title.align = 'center'
fig.extra_y_ranges = {'c_count': Range1d(start=0, end=10)}
fig.add_layout(LinearAxis(y_range_name='c_count'), 'right')
fig.vbar(bottom=0, top=[1, 2, 3], x=['a:0.35', 'b:0.35', 'c:0.35'], color='blue', legend='Amt', width=0.3, alpha=0.5)
fig.vbar(bottom=0, top=[5, 7, 8], x=['a:0.65', 'b:0.65', 'c:0.65'], color='green', legend='Ct', width=0.3, alpha=0.8, y_range_name='c_count')
fig.yaxis[0].formatter = NumeralTickFormatter(format='0.0')
bp.output_file('bar.html')
bp.show(fig)
A couple of notes:
Categorical axes are currently a bit (ahem) ugly in Bokeh. We hope to address this in the coming months. Each one has a scale of 0 - 1 after a colon which allows you to move things left and right. So I move the first bar to the left by 0.3/2 and the second bar to the right by 0.3/2 (0.3 because that's the width you had used)
The y_range changed because you were using the default y_range for your initial y_range which is a DataRange1d. DataRange uses all the data for the plot to pick its values and adds some padding which is why it was starting at below 0 and going up to the max of your new data. By manually specifying a range in the figure call you get around this.
Thanks for providing a code sample to work from :D