Bokeh Server callback from tools

Edit from project maintainers.

There was some confusion and regressions around selections leading up to 1.0. For any post 1.0 version, for most use case you would now want to use a callback on the 'indices' property of selected:

source.selected.on_change('indices', callback)

This kind of usage is now continuously and rigorously maintained under integration tests, and is what should be used for any post 1.0 Bokeh version.

---

The selected event can be linked to an update function as follows:

from bokeh.plotting import figure, curdoc
from bokeh.layouts import column
from bokeh.models import ColumnDataSource

TOOLS = "tap"
p = figure(title="Some Figure", tools=TOOLS)

source = ColumnDataSource(dict(x=[[1, 3, 2], [3, 4, 6, 6]],
                y=[[2, 1, 4], [4, 7, 8, 5]], name=['A', 'B']))

pglyph = p.patches('x', 'y', source=source, color=["firebrick", "navy"],
                                alpha=[0.8, 0.3], line_width=2)

def callback(attr, old, new):
    # The index of the selected glyph is : new['1d']['indices'][0]
    patch_name =  source.data['name'][new['1d']['indices'][0]]
    print("TapTool callback executed on Patch {}".format(patch_name))

pglyph.data_source.on_change('selected',callback)

curdoc().add_root(column(p))

Update for newer Bokeh versions. Tested on version 0.12.16

As @Karel Marik mentions glyphs can not mixed direct values assignment and ColumnDataSource at the same time. So the previous code does not work. Here is an update using only source which also includes code to print the multiple selections (made with shift + click):

from bokeh.plotting import figure, curdoc
from bokeh.layouts import column
from bokeh.models import ColumnDataSource

TOOLS = ["tap"]
p = figure(title="Some Figure", tools=TOOLS)

source = ColumnDataSource(dict(
    x=[[1, 3, 2], [3, 4, 6, 6]],
    y=[[2, 1, 4], [4, 7, 8, 5]],
    name=['A', 'B'],color=["firebrick", "navy"],
    alpha=[0.8,0.3],line_width=[3,3]))

pglyph = p.patches('x', 'y', color="color", alpha="alpha",
                   line_width="line_width", source=source)

def callback(attr, old, new):
    # The index of the selected glyph is : new['1d']['indices'][0]
    selections = new['1d']['indices']
    print("Number of selections:{}".format(len(selections)))
    for index in selections:
        patch_name =  source.data['name'][index]
        print("TapTool callback executed on Patch {}".format(patch_name))

pglyph.data_source.on_change('selected',callback)

curdoc().add_root(column(p))