Sum data inside selection in bokeh image plot

Question

I am starting with bokeh and I wonder if anyone could point me in the right direction.

I have an image (2D array). Using the gallery example:

import numpy as np

from bokeh.plotting import figure, show
from bokeh.models import ColumnDataSource, RangeTool
from bokeh.layouts import column

x = np.linspace(0, 10, 300)
y = np.linspace(0, 10, 300)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx) * np.cos(yy)

# Figures creation
im_fig = figure(width=400, height=400)

# Plotting the data
im_fig.image(image=[d], x=0, y=0, dw=10, dh=10, palette="Sunset11", level="image")
im_fig.grid.grid_line_width = 0.5

show(im_fig)

Which results in:

Now I would like to sum the data along a y selection. This seems to be the work of the RangeTool.

I create another figure to plot the summed data of the selection but I get an error while adding the initial range:

import numpy as np

from bokeh.plotting import figure, show
from bokeh.models import ColumnDataSource, RangeTool
from bokeh.layouts import column

x = np.linspace(0, 10, 300)
y = np.linspace(0, 10, 300)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx) * np.cos(yy)

# Figures creation
im_fig = figure(width=400, height=400)
sum_fig = figure(width=400, height=200)

# Plotting the data
im_fig.image(image=[d], x=0, y=0, dw=10, dh=10, palette="Sunset11", level="image")
im_fig.grid.grid_line_width = 0.5

# Adding the range tools
range_tool = RangeTool(y_range=im_fig.y_range)
range_tool.overlay.fill_color = "navy"
range_tool.overlay.fill_alpha = 0.2
im_fig.add_tools(range_tool)
im_fig.toolbar.active_multi = range_tool

show(column(im_fig, sum_fig))

This is the error:

failed to validate RangeTool(id='p1108', ...).y_range: expected either None or a value of type Instance(Range1d), got DataRange1d(id='p1003', ...)

My guess, this is happening because the Range tool is not compatible with the Image glyph. I wonder if anyone could please point me towards the right direction. Ty.

score 0 · Answer 1 · answered Jun 22 '23 at 14:33

RangeTool is compatible with the Image glyph. The issue in your code is that im_fig.y_rangeis not initialised in the code line

im_fig = figure(width=400, height=400)

Furthermore, you did not plot anything on sum_fig resulting in a blank figure. I am not source what you want to plot as a sum but here is a working version of your code with bokeh==3.0.1 and numpy numpy==1.22.3.

import numpy as np

from bokeh.plotting import figure, show
from bokeh.models import ColumnDataSource, RangeTool
from bokeh.layouts import column

x = np.linspace(0, 10, 300)
y = np.linspace(0, 10, 300)
xx, yy = np.meshgrid(x, y)
d = np.sin(xx) * np.cos(yy)

# Figures creation
im_fig = figure(width=400, height=400, y_range=(0, 10))
sum_fig = figure(width=400, height=200, tools="", toolbar_location=None)

# Plotting the data
im_fig.image(image=[d], x=0, y=0, dw=10, dh=10, palette="Sunset11", level="image")
im_fig.grid.grid_line_width = 0.5

sum_fig.image(image=[np.repeat(d.sum(axis=1).reshape(-1, 1), 300, axis=1)],
              x=0, y=0, dw=10, dh=10, palette="Sunset11", level="image")

# Adding the range tools
range_tool = RangeTool(y_range=im_fig.y_range)
range_tool.overlay.fill_color = "navy"
range_tool.overlay.fill_alpha = 0.2
sum_fig.add_tools(range_tool)
sum_fig.toolbar.active_multi = range_tool

show(column(im_fig, sum_fig))

The result looks like this

Reference: range_tool

Sum data inside selection in bokeh image plot

1 Answers1