Configuring Plot Tools¶

Bokeh comes with a number of interactive tools that can be used 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 are tools that 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, one tool can be active at any given time, and the active tool is indicated on the toolbar by a highlight 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 will potentially deactivate multiple single-gesture tools at once when it is activated.

In addition to information about all the individual tools, this chapter describes how the toolbar may be configured.

Specifying Tools¶

At the lowest bokeh.models level, tools are added to a Plot by passing instances of Tool objects to the add_tools method:

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

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

Tools can be specified by passing the tools parameter to the figure() function. The tools parameter accepts a list of tool objects, for instance:

tools = [BoxZoomTool(), ResetTool()]

Tools can also be supplied conveniently with a comma-separated string containing tool shortcut names:

tools = "pan,wheel_zoom,box_zoom,reset"

However, this method does not allow setting properties of the tools.

Finally, it is also always possible to add new tools to a plot by passing a tool object to the add_tools method of a plot. This can also be done in conjunction with the tools keyword described above:

from bokeh.models import BoxSelectTool

plot = figure(tools="pan,wheel_zoom,box_zoom,reset")
plot.add_tools(BoxSelectTool(dimensions="width"))

Setting the Active Tools¶

Bokeh toolbars can have (at most) one active tool from each kind of gesture (drag, scroll, tap). By default, Bokeh will use a default pre-defined order of preference to choose one of each kind from the set of configured tools, to be active.

However, it is possible to exert control over which tool is active. At the lowest bokeh.models level, this is accomplished 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".

Active tools can be specified by passing the these properties as keyword arguments to the figure() function. It is also possible to pass any one of the string names for, ease of configuration:

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

Pan/Drag Tools¶

These tools are employed 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 the user to define a rectangular selection region by left-dragging a mouse, or dragging a finger across the plot area. The box select tool may be configured 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 a multiple selection, press the SHIFT key. To clear the selection, press the ESC key.

BoxZoomTool¶

name: 'box_zoom'
icon:

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

LassoSelectTool¶

name: 'lasso_select'
icon:

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

It is also possible to constrain the pan tool to only act on either just the x-axis or just the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool aliases 'xpan' and 'ypan', respectively.

Click/Tap Tools¶

These tools are employed 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 the user 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 the user to select at single points by clicking a 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¶

These tools are employed 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:

The wheel zoom tool will zoom the plot in and out, centered on the current mouse location. It will respect any min and max values and ranges, preventing zooming in and out beyond these values.

It is also possible to constraint the wheel zoom tool to only act on either just the x-axis or just the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool aliases 'xwheel_zoom' and 'ywheel_zoom', respectively.

WheelPanTool¶

name: 'xwheel_pan', 'ywheel_pan'
icon:

The wheel pan tool will translate the plot window along the specified dimension without changing the window’s aspect ratio. The tool 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 allows to restore 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 will restore the plot ranges to their original values.

SaveTool¶

name: 'save'
icon:

The save tool pops up a modal dialog that allows the user to save a PNG image of the plot.

ZoomInTool¶

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

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

It is also possible to constraint the wheel zoom tool to only act on either just the x-axis or just the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool aliases 'xzoom_in' and 'yzoom_in', respectively.

ZoomOutTool¶

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

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

It is also possible to constraint the wheel zoom tool to only act on either just the x-axis or just the y-axis by setting the dimensions property to a list containing width or height. Additionally, there are tool aliases 'xzoom_in' and 'yzoom_in', respectively.

Inspectors¶

Inspectors are passive tools that annotate or otherwise report information about the plot, based on the current cursor position. Any number of inspectors may be active at any given time. The inspectors menu in the toolbar allows users to toggle the active state of any inspector.

CrosshairTool¶

name: 'crosshair'
menu icon:

Th crosshair tool draws a crosshair annotation over the plot, centered on the current mouse position. The crosshair tool draw dimensions may be configured by setting the dimensions property to one of the enumerated values width, height, or both.

HoverTool¶

name: 'hover'
menu icon:

The hover tool is a passive inspector tool. It is generally on at all times, but can be configured in the inspector’s menu associated with the toolbar.

Basic Tooltips¶

By default, the hover tool will generate 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"),
    ("foo", "@foo"),
    ("bar", "@bar"),
]

Field names that begin with $ are “special fields”. These often correspond to values that are intrinsic to 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
$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
$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), and swatch to also display a small color swatch.

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, then the hover tooltip will correspondingly display the 17th price value.

Note that if a column name contains spaces, it must be supplied by surrounding it in curly braces, e.g. @{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. The field name @$name is distinguished in that it will look up the name field on the hovered glyph renderer, and use that value as the column name. For instance, if a user hovers with the name "US East", then @$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(plot_width=400, plot_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 informational tooltips associated with individual glyphs. These tooltips can be configured 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". This can be observed in the Basic Tooltips example above. The example below in Formatting Tooltip Fields demonstrates an example that sets mode = "vline".

Image Hover¶

The hover tool can be used 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, named 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: Clear the selection

Note

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

BoxEditTool¶

name: 'box_edit'
menu icon:

The BoxEditTool allows drawing, dragging, and deleting Rect glyphs on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, the renderers that are to be edited must be supplied explicitly 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 will automatically modify the columns on 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 box. When drawing a new box, the data will always be added to the ColumnDataSource on the first supplied renderer.

It is also often useful to limit the number of elements that can be drawn, e.g. when specifying a specific number of regions of interest. Using the num_objects property, we can ensure that once the limit has been reached, the oldest box will be popped off the queue to make space for the new 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, the renderers that are to be edited must be supplied explicitly as a list:

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

The tool will automatically modify 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, e.g. when specifying a specific number of regions of interest. Using the num_objects property, we 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 adding, dragging, and deleting point-like glyphs (of XYGlyph type) on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, the renderers that are to be edited must be supplied explicitly 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 will automatically modify 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 on 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, we 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 drawing, selecting, and deleting Patches and MultiLine glyphs on one or more renderers by editing the underlying ColumnDataSource data. Like other drawing tools, the renderers that are to be edited must be supplied explicitly as a list.

The tool will automatically modify 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, e.g. when specifying a specific number of regions of interest. Using the num_objects property, we 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 it 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

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 Add, Move, and Delete patches and multi-lines:

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 editing the vertices of one or more Patches or MultiLine glyphs. The glyphs to be edited can be defined via the renderers property. The renderer for the vertices can be defined via the vertex_renderer, which must render a point-like Glyph (of XYGlyph type).

The tool will automatically modify 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.

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-ish (but not enormous) 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.

The basic idea is that during interactive operations (e.g., panning or zooming), the plot only draws some small fraction of data points. This hopefully allows the general sense of the interaction to be preserved mid-flight, while maintaining interactive performance. There are four properties on Plot objects that control LOD behavior:

lod_factor¶

property type: Int

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

lod_interval¶

property type: Int

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

lod_threshold¶

property type: 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¶

property 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¶

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¶

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¶