MATLAB Function Reference

datacursormode - Enable or disable interactive data cursor mode

GUI Alternatives

Use the Data Cursor tool to label x, y, and z values on graphs and surfaces. For details, see Data Cursor — Displaying Data Values Interactively in the MATLAB^® Graphics documentation.

Syntax

datacursormode on datacursormode off datacursormode datacursormode(figure_handle,...) dcm_obj = datacursormode(figure_handle)

Description

datacursormode on enables data cursor mode on the current figure.

datacursormode off disables data cursor mode on the current figure.

datacursormode toggles data cursor mode on the current figure.

datacursormode(figure_handle,...) enables or disables data cursor mode on the specified figure.

dcm_obj = datacursormode(figure_handle) returns the figure's data cursor mode object, which enables you to customize the data cursor. See Data Cursor Mode Object.

Data Cursor Mode Object

The data cursor mode object has properties that enable you to controls certain aspects of the data cursor. You can use the set and get commands and the returned object (dcm_obj in the above syntax) to set and query property values.

Data Cursor Mode Properties

Enable

on | off

Specifies whether this mode is currently enabled on the figure.

SnapToDataVertex

on | off

Specifies whether the data cursor snaps to the nearest data value or is located at the actual pointer position.

DisplayStyle

datatip | window

Determines how the data is displayed.

datatip displays cursor information in a yellow text box next to a marker indicating the actual data point being displayed.
window displays cursor information in a floating window within the figure.

Updatefcn

function handle

This property references a function that customizes the text appearing in the data cursor. The function handle must reference a function that has two implicit arguments (these arguments are automatically passed to the function when it executes). For example, the following function definition line uses the required arguments:

function output_txt = myfunction(obj,event_obj)
% obj				Currently not used (empty)
% event_obj				Handle to event object
% output_txt				Data cursor text string (string or cell array of
% 				strings).

event_obj is an object having the following read-only properties.

Target — Handle of the object the data cursor is referencing (the object on which the user clicked).
Position — An array specifying the x, y, (and z for 3-D graphs) coordinates of the cursor.

You can query these properties within your function. For example,

pos = get(event_obj,'Position');

returns the coordinates of the cursor.

See Function Handles for more information on creating a function handle.

See Change Data Cursor Text for an example.

Data Cursor Method

You can use the getCursorInfo function with the data cursor mode object (dcm_obj in the above syntax) to obtain information about the data cursor. For example,

info_struct = getCursorInfo(dcm_obj);

returns a vector of structures, one for each data cursor on the graph. Each structure has the following fields:

Target — The handle of the graphics object containing the data point.
Position — An array specifying the x, y, (and z) coordinates of the cursor.

Line and lineseries objects have an additional field:

DataIndex — A scalar index into the data arrays that correspond to the nearest data point. The value is the same for each array.

Examples

This example creates a plot and enables data cursor mode from the command line.

surf(peaks)
datacursormode on
% Click mouse on surface to display data cursor

Setting Data Cursor Mode Options

This example enables data cursor mode on the current figure and sets data cursor mode options. The following statements

Create a graph
Toggle data cursor mode to on

Save the data cursor mode object to specify options and get the handle of the line to which the datatip is attached

fig = figure;
z = peaks;
plot(z(:,30:35))
dcm_obj = datacursormode(fig);
set(dcm_obj,'DisplayStyle','datatip',...
'SnapToDataVertex','off','Enable','on')

% Click on line to place datatip

c_info = getCursorInfo(dcm_obj);
set(c_info.Target,'LineWidth',2) % Make selected line wider

Change Data Cursor Text

This example shows you how to customize the text that is displayed by the data cursor. Suppose you want to replace the text displayed in the datatip and data window with "Time:" and "Amplitude:"

function doc_datacursormode
fig = figure;
a = -16; t = 0:60;
plot(t,sin(a*t))
dcm_obj = datacursormode(fig);
set(dcm_obj,'UpdateFcn',@myupdatefcn)

% Click on line to select data point

function txt = myupdatefcn(empt,event_obj)
pos = get(event_obj,'Position');
txt = {['Time: ',num2str(pos(1))],...
	['Amplitude: ',num2str(pos(2))]};