Image plot not updating

Community Support
1

Hi,

I’m trying to build an interactive plot that changes an image plot based on values on a slider, similar to what the example notebook Jupyter Interactors.ipynb does for a line plot. I’m using jupyter notebook, and running the example notebook works fine.

For the image plot, I’ve done the following:

color_mapper = LinearColorMapper(palette=“Viridis256”, low=0, high=200)

p = figure(plot_width=400, plot_height=400, x_range=(0, 400), y_range=(0, 00))

img = p.image(image=[my_array], x=[0], y=[0], dw=[400], dh=[400],

          color_mapper=color_mapper)

show(p, notebook_handle=True)

Now, if I try to modify the image data with the following:

img.data_source.data[‘image’] = new_array

push_notebook()

This new_array has the same shape as the original my_array. This produces no change in the figure and gives the following error:

  /Users/yyy/miniconda/lib/python3.6/site-packages/bokeh/models/sources.py:110: BokehUserWarning: ColumnDataSource's columns must be of the same length. Current lengths: ('dh', 1), ('dw', 1), ('image', 2), ('x', 1), ('y', 1)
"Current lengths: %s" % ", ".join(sorted(str((k, len(v))) for k, v in data.items())), BokehUserWarning))



I get the same warning and lack of change if I try to change any other parameters of the data source (e.g. x, y, dw, dh).



Is this a bug, or am I doing something wrong? How can I update an image plot?





Thanks,



Tiago
2

Just found the solution. Apparently I need to enclose the new array in a list:

img.data_source.data[‘image’] = [new_array]

And now it works!

Tiago

···

On Wednesday, August 1, 2018 at 5:14:39 PM UTC+2, Tiago Pereira wrote:

Hi,

I’m trying to build an interactive plot that changes an image plot based on values on a slider, similar to what the example notebook Jupyter Interactors.ipynb does for a line plot. I’m using jupyter notebook, and running the example notebook works fine.

For the image plot, I’ve done the following:

color_mapper = LinearColorMapper(palette=“Viridis256”, low=0, high=200)

p = figure(plot_width=400, plot_height=400, x_range=(0, 400), y_range=(0, 00))

img = p.image(image=[my_array], x=[0], y=[0], dw=[400], dh=[400],

          color_mapper=color_mapper)

show(p, notebook_handle=True)

Now, if I try to modify the image data with the following:

img.data_source.data[‘image’] = new_array

push_notebook()

This new_array has the same shape as the original my_array. This produces no change in the figure and gives the following error:

/Users/yyy/miniconda/lib/python3.6/site-packages/bokeh/  models/sources.py:110: BokehUserWarning: ColumnDataSource's columns must be of the same length. Current lengths: ('dh', 1), ('dw', 1), ('image', 2), ('x', 1), ('y', 1)
"Current lengths: %s" % ", ".join(sorted(str((k, len(v))) for k, v in data.items())), BokehUserWarning))




I get the same warning and lack of change if I try to change any other parameters of the data source (e.g. x, y, dw, dh).




Is this a bug, or am I doing something wrong? How can I update an image plot?







Thanks,




Tiago