Bokeh, Python: How to update range of extra axis

Question

I would like to create a plot with 2 y-axes, whose ranges are being updated on a button click. The script would run on a Bokeh server. Note that in the code below, the primary y-axis is being updated by changing f.y_range.start/end. However, this is not possible with the secondary y-axis. I tried two other commands instead, i.e.

f.extra_y_ranges.update({"y2Range": Range1d(start=0, end=50)})

and

f.extra_y_ranges.update = {"y2Range": Range1d(start=0, end=50)}

But none of them work.

A similar questions was asked here: Bokeh: How to change extra axis visibility

# Import libraries
from bokeh.io import curdoc
from bokeh.models import ColumnDataSource, Range1d, LinearAxis
from bokeh.models.widgets import Button
from bokeh.layouts import layout
from bokeh.plotting import figure


# Create figure
f=figure()

# Create ColumnDataSource
source = ColumnDataSource(dict(x=range(0,100),y=range(0,100)))

# Create Line
f.line(x='x',y='y',source=source)
f.extra_y_ranges = {"y2Range": Range1d(start=0, end=100)}
f.add_layout(LinearAxis(y_range_name='y2Range'), 'left')

# Update axis function
def update_axis():
    f.y_range.start = 0 
    f.y_range.end   = 50

# Create Button
button = Button(label='Set Axis')

# Update axis range on click
button.on_click(update_axis)

# Add elements to curdoc 
lay_out=layout([[f, button]])
curdoc().add_root(lay_out)

Answer 1

I was facing a similar problem. I was able to update the range of the secondary axis by accessing it through the 'extra_y_axis' dict via the name I created it with. For your case, it should look something like:

---

# Update primary axis function
def update_axis():
    f.y_range.start = 0 
    f.y_range.end   = 50   

# Update secondary axis function
def update_secondary_axis():
    f.extra_y_ranges['y2Range'].start = -20 #new secondary axis min
    f.extra_y_ranges['y2Range'].end = 80 #new secondary axis max