Configuring plot tools#

Bokeh comes with a number of interactive tools that you can use to report information, to change plot parameters such as zoom level or range extents, or to add, edit, or delete glyphs. Tools can be grouped into four basic categories:

Gestures

These tools respond to single gestures, such as a pan movement. The types of gesture tools are:

Pan/Drag tools
Click/Tap tools
Scroll/Pinch tools

For each type of gesture, only one tool can be active at any given time. The active tool is highlighted on the toolbar next to the tool icon.

Actions

These are immediate or modal operations that are only activated when their button in the toolbar is pressed, such as the ResetTool.

Inspectors

These are passive tools that report information or annotate plots in some way, such as the HoverTool or CrosshairTool.

Edit tools

These are sophisticated multi-gesture tools that can add, delete, or modify glyphs on a plot. Since they may respond to several gestures at once, an edit tool when activated will potentially deactivate multiple single-gesture tools.

This chapter contains information about all the individual tools and describes how the toolbar may be configured.

Specifying tools#

At the lowest bokeh.models level, you can add tools to a Plot by passing instances of Tool objects to the add_tools() method:

from bokeh.models import LassoSelectTool, Plot, WheelZoomTool

plot = Plot()
plot.add_tools(LassoSelectTool())

wheel = WheelZoomTool()
plot.add_tools(wheel)

This way of adding tools works with any Bokeh Plot or Plot subclass, such as figure.

You can specify tools by passing the tools parameter to the figure() function. The tools parameter accepts a list of tool objects, for example:

from bokeh.models import BoxZoomTool, ResetTool
from bokeh.plotting import figure

plot = figure(tools=[BoxZoomTool(), ResetTool()])

You can also add multiple tools with a comma-separated string containing tool shortcut names:

from bokeh.plotting import figure

plot = figure(tools="pan,wheel_zoom,box_zoom,reset")

This method does not allow setting properties of the tools.

Remove tools by passing a tool object to the remove_tools() method of a plot.

from bokeh.models import BoxSelectTool, WheelZoomTool
from bokeh.plotting import figure

tools = box, wheel = BoxSelectTool(dimensions="width"), WheelZoomTool()
plot = figure(tools=tools)

plot.remove_tools(box)

Customizing tools icon#

You can change the tools tooltip by passing it to the description keyword using the add_tools() method of a plot or any of it’s instances like figure().

plot.add_tools(BoxSelectTool(description="My tool"))

It’s also possible to change a tool icon using the icon keyword.

You can pass:

A well known icon name

plot.add_tools(BoxSelectTool(icon="box_zoom"))

A CSS selector

plot.add_tools(BoxSelectTool(icon=".my-icon-class"))

An image path

plot.add_tools(BoxSelectTool(icon="path/to/icon"))

Setting the active tools#

Bokeh toolbars can have at most one active tool from each kind of gesture (drag, scroll, tap).

However, it is possible to exert control over which tool is active. At the lowest bokeh.models level, you can do this by using the active_drag, active_inspect, active_scroll, and active_tap properties of Toolbar. These properties can take the following values:

None — there is no active tool of this kind
"auto" — Bokeh chooses a tool of this kind to be active (possibly none)
a Tool instance — Bokeh sets the given tool to be the active tool

Additionally, the active_inspect tool may accept: * A sequence of Tool instances to be set as the active tools

As an example:

# configure so that no drag tools are active
plot.toolbar.active_drag = None

# configure so that Bokeh chooses what (if any) scroll tool is active
plot.toolbar.active_scroll = "auto"

# configure so that a specific PolySelect tap tool is active
plot.toolbar.active_tap = poly_select

# configure so that a sequence of specific inspect tools are active
# note: this only works for inspect tools
plot.toolbar.active_inspect = [hover_tool, crosshair_tool]

The default value for all of these properties is "auto".

You can specify active tools by passing these properties as keyword arguments to the figure() function. It is also possible to pass any one of the string names:

# configures the lasso tool to be active
plot = figure(tools="pan,lasso_select,box_select", active_drag="lasso_select")

Pan/Drag tools#

You can use these tools by panning (on touch devices) or left-dragging (on mouse devices). Only one pan/drag tool may be active at a time. Where applicable, Pan/Drag tools will respect any max and min values set on ranges.

BoxSelectTool#

name: 'box_select'
icon:

The box selection tool allows you to define a rectangular selection by left-dragging a mouse, or dragging a finger across the plot area. You can configure the box select tool to select across only one dimension by setting the dimensions property to width or height instead of the default both.

After a selection is made, the indices of the selected points are available from properties on the Selection object for a glyph data source. For example:

source.selected.indices

will hold the selected indices in the common case of a “scatter” type glyph.

Note

To make multiple selections, press the SHIFT key. To clear the selection, press the ESC key.

BoxZoomTool#

name: 'box_zoom'
icon:

The box zoom tool allows you to define a rectangular region to zoom the plot bounds to by left-dragging a mouse, or dragging a finger across the plot area.

LassoSelectTool#

name: 'lasso_select'
icon:

The lasso selection tool allows you to define an arbitrary region for selection by left-dragging a mouse, or dragging a finger across the plot area.

After a selection is made, the indices of the selected points are available from properties on the Selection object for a glyph data source. For example:

source.selected.indices

will hold the selected indices in the common case of a “scatter” type glyph.

Note

To make a multiple selection, press the SHIFT key. To clear the selection, press the ESC key.

PanTool#

name: 'pan', 'xpan', 'ypan',
icon:

The pan tool allows you to pan the plot by left-dragging a mouse or dragging a finger across the plot region.

You can configure the pan tool to act only on either the x-axis or the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool names 'xpan' and 'ypan', respectively.

Click/Tap tools#

Use these tools by tapping (on touch devices) or left-clicking (on mouse devices). Only one click/tap tool may be active at a time.

PolySelectTool#

name: 'poly_select'
icon:

The polygon selection tool allows you to define an arbitrary polygonal region for selection by left-clicking a mouse, or tapping a finger at different locations.

After a selection is made, the indices of the selected points are available from properties on the Selection object for a glyph data source. For example:

source.selected.indices

will hold the selected indices in the common case of a “scatter” type glyph.

Note

Complete the selection by making a double left-click or tapping. To make a multiple selection, press the SHIFT key. To clear the selection, press the ESC key.

TapTool#

name: 'tap'
icon:

The tap selection tool allows you to select single points by clicking the left mouse button, or tapping with a finger.

After a selection is made, the indices of the selected points are available from properties on the Selection object for a glyph data source. For example:

source.selected.indices

will hold the selected indices in the common case of a “scatter” type glyph.

Note

To make a multiple selection, press the SHIFT key. To clear the selection, press the ESC key.

Scroll/Pinch tools#

Use these tools by pinching (on touch devices) or scrolling (on mouse devices). Only one scroll/pinch tool may be active at a time.

WheelZoomTool#

name: 'wheel_zoom', 'xwheel_zoom', 'ywheel_zoom'
icon:

You can use the wheel zoom tool to zoom the plot in and out, centering on the current mouse location. It will respect any min and max values and ranges, preventing zooming in and out beyond these values.

You can configure the wheel zoom tool to act only on either the x-axis or the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool names 'xwheel_zoom' and 'ywheel_zoom', respectively.

WheelPanTool#

name: 'xwheel_pan', 'ywheel_pan'
icon:

The wheel pan tool translates the plot window along a specified dimension without changing the window’s aspect ratio. It will respect any min and max values and ranges, preventing panning beyond these values.

Actions#

Actions are operations that are activated only when their button in the toolbar is tapped or clicked. They are typically modal or immediate-acting.

UndoTool#

name: 'undo'
icon:

The undo tool restores the previous state of the plot.

RedoTool#

name: 'redo'
icon:

The redo tool reverses the last action performed by the undo tool.

ResetTool#

name: 'reset'
icon:

The reset tool restores the plot ranges to their original values.

SaveTool#

name: 'save'
icon:

The save tool allows you to save a PNG image of the plot. By default, you will be prompted for a filename. Alternatively, you can create an instance of the tool yourself and provide a filename:

SaveTool(filename='custom_filename') # png extension not needed

Either way, the file will then be downloaded directly or a modal dialog will open depending on your browser.

ZoomInTool#

name: 'zoom_in', 'xzoom_in', 'yzoom_in'
icon:

The zoom-in tool increases the zoom of the plot. It will respect any min and max values and ranges, preventing zooming in and out beyond these.

ZoomOutTool#

name: 'zoom_out', 'xzoom_out', 'yzoom_out'
icon:

The zoom-out tool decreases the zoom level of the plot. It will respect any min and max values and ranges, preventing zooming in and out beyond these values.

Inspectors#

Inspectors are passive tools that annotate or report information about the plot based on the current cursor position. Multiple inspectors may be active at any given time. You can toggle the active state of an inspector in the inspectors menu in the toolbar.

CrosshairTool#

name: 'crosshair'
menu icon:

The crosshair tool draws a crosshair annotation over the plot, centered on the current mouse position. You can configure the crosshair tool dimensions by setting the dimensions property to width, height, or both.

HoverTool#

name: 'hover'
menu icon:

The hover tool is a passive inspector tool. It defaults to be on at all times, but you can change this in the inspector’s menu in the toolbar.

Basic Tooltips#

By default, the hover tool generates a “tabular” tooltip where each row contains a label and its associated value. The labels and values are supplied as a list of (label, value) tuples. For instance, the tooltip below on the left was created with the accompanying tooltips definition on the right.

hover_basic

hover.tooltips = [
    ("index", "$index"),
    ("(x,y)", "($x, $y)"),
    ("radius", "@radius"),
    ("fill color", "$color[hex, swatch]:fill_color"),
    ("fill color", "$color[hex]:fill_color"),
    ("fill color", "$color:fill_color"),
    ("fill color", "$swatch:fill_color"),
    ("foo", "@foo"),
    ("bar", "@bar"),
]

Field names that begin with $ are “special fields”. These often correspond to values that are part of the plot, such as the coordinates of the mouse in data or screen space. These special fields are listed here:

$index: index of selected point in the data source
$glyph_view: a reference to the glyph view for the glyph that was hit
$name: value of the name property of the hovered glyph renderer
$x: x-coordinate under the cursor in data space
$y: y-coordinate under the cursor in data space
$sx: x-coordinate under the cursor in screen (canvas) space
$sy: y-coordinate under the cursor in screen (canvas) space
$snap_x: x-coordinate where the tooltip is anchored in data space
$snap_y: y-coordinate where the tooltip is anchored in data space
$snap_sx: x-coordinate where the tooltip is anchored in screen (canvas) space
$snap_sy: y-coordinate where the tooltip is anchored in screen (canvas) space
$color: colors from a data source, with the syntax: $color[options]:field_name. The available options are: hex (to display the color as a hex value), swatch (color data from data source displayed as a small color box).
$swatch: color data from data source displayed as a small color box.

Additionally, certain glyphs may report additional data that is specific to that glyph

$indices: indices of all the selected points in the data source
$segment_index: segment index of a selected sub-line (multi-line glyphs only)
$image_index: pixel index into an image array (image glyphs only)

Field names that begin with @ are associated with columns in a ColumnDataSource. For instance, the field name "@price" will display values from the "price" column whenever a hover is triggered. If the hover is for the 17th glyph instance, then the hover tooltip will display the 17th price value.

Note that if a column name contains spaces, it must be surrounded by curly braces. For example, configuring @{adjusted close} will display values from a column named "adjusted close".

Sometimes, especially with stacked charts, it is desirable to allow the name of the column to be specified indirectly. In this case, use the field name @$name to look up the name field on the hovered glyph renderer, and use that value as the column name. For instance, if you hover with the name "US East", then @$name is equivalent to @{US East}.

Here is a complete example of how to configure and use the hover tool by setting the tooltips argument to figure:

from bokeh.plotting import ColumnDataSource, figure, output_file, show

output_file("toolbar.html")

source = ColumnDataSource(data=dict(
    x=[1, 2, 3, 4, 5],
    y=[2, 5, 8, 2, 7],
    desc=['A', 'b', 'C', 'd', 'E'],
))

TOOLTIPS = [
    ("index", "$index"),
    ("(x,y)", "($x, $y)"),
    ("desc", "@desc"),
]

p = figure(width=400, height=400, tooltips=TOOLTIPS,
           title="Mouse over the dots")

p.circle('x', 'y', size=20, source=source)

show(p)

Hit-Testing behavior#

The hover tool displays tooltips associated with individual glyphs. You can configure these tooltips to activate in different ways with a mode property:

"mouse":: only when the mouse is directly over a glyph
"vline":: whenever a vertical line from the mouse position intersects a glyph
"hline":: whenever a horizontal line from the mouse position intersects a glyph

The default configuration is mode = "mouse". See this in the Basic Tooltips example above. The example below in Formatting tooltip fields demonstrates mode = "vline".

Image hover#

You can use the hover tool to inspect image glyphs which may contain layers of data in the corresponding ColumnDataSource:

import numpy as np

from bokeh.plotting import figure, output_file, show

output_file("tools_hover_tooltip_image.html")

ramp = np.array([np.linspace(0, 10, 200)]*20)
steps = np.array([np.linspace(0, 10, 10)]*20)
bitmask = np.random.rand(25, 10) > 0.5

data = dict(image=[ramp, steps, bitmask],
            squared=[ramp**2, steps**2, bitmask**2],
            pattern=['smooth ramp', 'steps', 'bitmask'],
            x=[0, 0, 25],
            y=[5, 20, 5],
            dw=[20,  20, 10],
            dh=[10,  10, 25])

TOOLTIPS = [
    ('name', "$name"),
    ('index', "$index"),
    ('pattern', '@pattern'),
    ("x", "$x"),
    ("y", "$y"),
    ("value", "@image"),
    ('squared', '@squared')
]

p = figure(x_range=(0, 35), y_range=(0, 35), tools='hover,wheel_zoom', tooltips=TOOLTIPS)
p.image(source=data, image='image', x='x', y='y', dw='dw', dh='dh', palette="Inferno256", name="Image Glyph")

show(p)

In this example, three image patterns are defined, ramp, steps, and bitmask. The hover tooltip shows the index of the image, the name of the pattern, the x and y position of the cursor, as well as the corresponding value and value squared.

Edit tools#

The edit tools provide functionality for drawing and editing glyphs client-side by adding, modifying, and deleting ColumnDataSource data.

All the edit tools share a small number of key bindings:

SHIFT: Modifier key to add to selection or start drawing
BACKSPACE: Deletes the selected glyphs
ESC: Clears the selection

Note

On MacBooks and some other keyboards, the BACKSPACE key is labeled “delete”.

BoxEditTool#

name: 'box_edit'
menu icon:

The BoxEditTool() allows you to draw, drag, and delete Rect glyphs on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, you must pass the renderers to be edited as a list:

r1 = p.rect('x', 'y', 'width', 'height', source=source)
r2 = p.rect('x', 'y', 'width', 'height', source=source2)
tool = BoxEditTool(renderers=[r1, r2])

The tool automatically modifies the columns of the data source corresponding to the x, y, width, and height values of the glyph. Any additional columns in the data source will be padded with the declared empty_value when adding a new point. Any newly added points will be inserted in the ColumnDataSource of the first supplied renderer.

It is often useful to limit the number of elements that can be drawn. For example, when specifying a certain number of regions of interest. Using the num_objects property, you can ensure that once the limit has been reached, the oldest box will be popped off the queue to make space for the newest box being added.

Animation showing box draw, select, and delete actions

The animation above shows the supported tool actions, highlighting mouse actions with a circle around the cursor, and key strokes by showing the pressed keys. The BoxEditTool can Add, Move and Delete boxes on plots:

Add box: Hold shift, then click and drag anywhere on the plot or double tap once to start drawing. Move the mouse and double tap again to finish drawing.
Move box: Click and drag an existing box. The box will be dropped once you let go of the mouse button.
Delete box: Tap a box to select it, then press the BACKSPACE key while the mouse is within the plot area.

To Move or Delete multiple boxes at once:

Move selection: Select box(es) with SHIFT+tap (or another selection tool) then drag anywhere on the plot. Selecting and then dragging on a specific box will move both.
Delete selection: Select box(es) with SHIFT+tap (or another selection tool) then press BACKSPACE while the mouse is within the plot area.

FreehandDrawTool#

name: 'freehand_draw'
menu icon:

The FreehandDrawTool() allows freehand drawing of lines and polygons using the Patches and MultiLine glyphs, by editing the underlying ColumnDataSource data. Like other drawing tools, you must pass the renderers to be edited as a list:

r = p.multi_line('xs', 'ys' source=source)
tool = FreehandDrawTool(renderers=[r])

The tool automatically modifies the columns on the data source corresponding to the xs and ys values of the glyph. Any additional columns in the data source will be padded with the declared empty_value when adding a new point. Any newly added points will be inserted in the ColumnDataSource of the first supplied renderer.

It is also often useful to limit the number of elements that can be drawn. For example, when specifying a specific number of regions of interest. Using the num_objects property, you can ensure that once the limit has been reached, the oldest patch/multi-line will be popped off the queue to make space for the new patch/multi-line being added.

Animation showing freehand drawing and delete actions

The animation above shows the supported tool actions, highlighting mouse actions with a circle around the cursor, and key strokes by showing the pressed keys. The PolyDrawTool can Draw and Delete patches and multi-lines:

Draw patch/multi-line: Click and drag to start drawing and release the mouse button to finish drawing.
Delete patch/multi-line: Tap a line or patch to select it then press the BACKSPACE key while the mouse is within the plot area.

To Delete multiple patches/lines at once:
Delete selection: Select patches/lines with SHIFT+tap (or another selection tool), then press BACKSPACE while the mouse is within the plot area.

PointDrawTool#

name: 'point_draw'
menu icon:

The PointDrawTool() allows you to add, drag, and delete point-like glyphs (of XYGlyph type) on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, you must pass the renderers to be edited as a list:

c1 = p.circle('x', 'y', 'width', 'height', source=source)
r1 = p.rect('x', 'y', 0.1, 0.1, source=source2)
tool = PointDrawTool(renderers=[c1, r1])

The tool automatically modifies the columns on the data source corresponding to the x and y values of the glyph. Any additional columns in the data source will be padded with the declared empty_value when adding a new point. Any newly added points will be inserted in the ColumnDataSource of the first supplied renderer.

It is also often useful to limit the number of elements that can be drawn. Using the num_objects property, you can ensure that once the limit has been reached, the oldest point will be popped off the queue to make space for the new point being added.

Animation showing point draw, drag, select, and delete actions

The animation above shows the supported tool actions, highlighting mouse actions with a circle around the cursor, and key strokes by showing the pressed keys. The PointDrawTool can Add, Move, and Delete point-like glyphs on plots:

Add point: Tap anywhere on the plot.
Move point: Tap and drag an existing point. The point will be dropped once you let go of the mouse button.
Delete point: Tap a point to select it then press BACKSPACE key while the mouse is within the plot area.

To Move or Delete multiple points at once:

Move selection: Select point(s) with SHIFT+tap (or another selection tool), then drag anywhere on the plot. Selecting and then dragging a specific point will move both.
Delete selection: Select point(s) with SHIFT+tap (or another selection tool), then press BACKSPACE while the mouse is within the plot area.

PolyDrawTool#

name: 'poly_draw'
menu icon:

The PolyDrawTool() allows you to draw, select, and delete Patches and MultiLine glyphs on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, you must pass the renderers to be edited as a list.

The tool automatically modifies the columns on the data source corresponding to the xs and ys values of the glyph. Any additional columns in the data source will be padded with the declared empty_value, when adding a new point. Any newly added patch or multi-line will be inserted on the ColumnDataSource of the first supplied renderer.

It is also often useful to limit the number of elements that can be drawn. For example, when specifying a specific number of regions of interest. Using the num_objects property, you can ensure that once the limit has been reached the oldest patch/multi-line will be popped off the queue to make space for the new patch/multi-line being added.

If a vertex_renderer with a point-like glyph is supplied, the PolyDrawTool will use it to display the vertices of the multi-lines/patches on all supplied renderers. This also enables the ability to snap to existing vertices while drawing.

Animation showing polygon draw, select, and delete actions

Add patch/multi-line: Double tap to add the first vertex, then use tap to add each subsequent vertex. To finalize the draw action, double tap to insert the final vertex or press the ESC key.
Move patch/multi-line: Tap and drag an existing patch/multi-line. The point will be dropped once you let go of the mouse button.
Delete patch/multi-line: Tap a patch/multi-line to select it, then press the BACKSPACE key while the mouse is within the plot area.

PolyEditTool#

name: 'poly_edit'
menu icon:

The PolyEditTool() allows you to edit the vertices of one or more Patches or MultiLine glyphs. You can define the glyphs to be edited with the renderers property. You can define the renderer for the vertices with the vertex_renderer. It must render a point-like Glyph (of XYGlyph type).

Animation showing polygon and vertex drag, select, and delete actions

The animation above shows the supported tool actions, highlighting mouse actions with a circle around the cursor, and key strokes by showing the pressed keys. The PolyEditTool can Add, Move, and Delete vertices on existing patches and multi-lines:

Show vertices: Double tap an existing patch or multi-line.
Add vertex: Double tap an existing vertex to select it. The tool will draw the next point. To add it, tap in a new location. To finish editing and add a point, double tap. Otherwise press the ESC key to cancel.
Move vertex: Drag an existing vertex and let go of the mouse button to release it.
Delete vertex: After selecting one or more vertices, press BACKSPACE while the mouse cursor is within the plot area.

Controlling level of detail#

Although the HTML canvas can comfortably display tens or even hundreds of thousands of glyphs, doing so can have adverse effects on interactive performance. In order to accommodate large data sizes, Bokeh plots offer “Level of Detail” (LOD) capability in the client.

Note

Another option when dealing with very large data volumes is to use the Bokeh Server to perform downsampling on data before it is sent to the browser. Such an approach is unavoidable past a certain data size. See Running a Bokeh server for more information.

To maintain performance while handling large data sizes, the plot only draws a small fraction of data points during interactive operations (panning or zooming, for example). There are four properties on Plot objects that control LOD behavior:

lod_factor = 10#

Type:: Int

Decimation factor to use when applying level-of-detail decimation.

lod_interval = 300#

Type:: Int

Interval (in ms) during which an interactive tool event will enable level-of-detail downsampling.

lod_threshold = 2000#

Type:: Nullable(Int)

A number of data points, above which level-of-detail downsampling may be performed by glyph renderers. Set to None to disable any level-of-detail downsampling.

lod_timeout = 500#

Type:: Int

Timeout (in ms) for checking whether interactive tool events are still occurring. Once level-of-detail mode is enabled, a check is made every lod_timeout ms. If no interactive tool events have happened, level-of-detail mode is disabled.

Configuring plot tools#

Specifying tools#

Customizing tools icon#

Setting the active tools#

Pan/Drag tools#

BoxSelectTool#

BoxZoomTool#

LassoSelectTool#

PanTool#

Click/Tap tools#

PolySelectTool#

TapTool#

Scroll/Pinch tools#

WheelZoomTool#

WheelPanTool#

Actions#

UndoTool#

RedoTool#

ResetTool#

SaveTool#

ZoomInTool#

ZoomOutTool#

Inspectors#

CrosshairTool#

HoverTool#

Basic Tooltips#

Hit-Testing behavior#

Formatting tooltip fields#

Image hover#

Custom tooltip#

Edit tools#

BoxEditTool#

FreehandDrawTool#

PointDrawTool#

PolyDrawTool#

PolyEditTool#

Controlling level of detail#

Configuring plot tools#

Positioning the toolbar#

Specifying tools#

Customizing tools icon#

Setting the active tools#

Pan/Drag tools#

BoxSelectTool#

BoxZoomTool#

LassoSelectTool#

PanTool#

Click/Tap tools#

PolySelectTool#

TapTool#

Scroll/Pinch tools#

WheelZoomTool#

WheelPanTool#

Actions#

UndoTool#

RedoTool#

ResetTool#

SaveTool#

ZoomInTool#

ZoomOutTool#

Inspectors#

CrosshairTool#

HoverTool#

Basic Tooltips#

Hit-Testing behavior#

Formatting tooltip fields#

Image hover#

Custom tooltip#

Edit tools#

BoxEditTool#

FreehandDrawTool#

PointDrawTool#

PolyDrawTool#

PolyEditTool#

Controlling level of detail#