scatterhist

Scatter plot with marginal histograms

Syntax

scatterhist(x,y)

scatterhist(x,y,Name,Value)

h = scatterhist(___)

Description

scatterhist(x,y) creates a 2-D scatter plot of the data in vectors x and y, and displays the marginal distributions of x and y as univariate histograms on the horizontal and vertical axes of the scatter plot, respectively.

scatterhist(x,y,Name,Value) creates the plot using additional options specified by one or more name-value pair arguments. For example, you can specify a grouping variable or change the display options.

h = scatterhist(___) returns a vector of three axis handles for the scatter plot, the histogram along the horizontal axis, and the histogram along the vertical axis, respectively, using any of the input arguments in the previous syntaxes.

Examples

Create a scatterhist Plot

Load the sample data. Create data vector x from the first column of the data matrix, which contains sepal length measurements from iris flowers. Create data vector y from the second column of the data matrix, which contains sepal width measurements from the same flowers.

load fisheriris
x = meas(:,1);
y = meas(:,2);

Create a scatter plot and two marginal histograms to visualize the relationship between sepal length and sepal width.

scatterhist(x,y)

Display a data tip for a bin in a histogram. A data tip appears when you hover over a bin in a histogram.

The data tip displays the probability density function estimate of the selected bin and the lower and upper values for the bin edges.

Plot Grouped Data

Load the sample data. Create data vector x from the first column of the data matrix, which contains sepal length measurements from three species of iris flowers. Create data vector y from the second column of the data matrix, which contains sepal width measurements from the same flowers.

load fisheriris.mat;
x = meas(:,1);
y = meas(:,2);

Create a scatter plot and six kernel density plots to visualize the relationship between sepal length and sepal width, grouped by species.

scatterhist(x,y,'Group',species,'Kernel','on')

The plot shows that the relationship between sepal length and width varies depending on the flower species.

Customize the Plot Display

Load the sample data. Create data vector x from the first column of the data matrix, which contains sepal length measurements from three different species of iris flowers. Create data vector y from the second column of the data matrix, which contains sepal width measurements from the same flowers.

load fisheriris.mat;
x = meas(:,1);
y = meas(:,2);

Create a scatter plot and six kernel density plots to visualize the relationship between sepal length and sepal width as measured on three species of iris flowers, grouped by species. Customize the appearance of the plots.

scatterhist(x,y,'Group',species,'Kernel','on','Location','SouthEast',...
    'Direction','out','Color','kbr','LineStyle',{'-','-.',':'},...
    'LineWidth',[2,2,2],'Marker','+od','MarkerSize',[4,5,6]);

Customize Plots Using Axes Handles

Load the sample data. Create data vector x from the first column of the data matrix, which contains sepal length measurements from three species of iris flowers. Create data vector y from the second column of the data matrix, which contains sepal width measurements from the same flowers.

load fisheriris.mat;
x = meas(:,1);
y = meas(:,2);

Use axis handles to replace the marginal histograms with box plots.

h = scatterhist(x,y,'Group',species);
hold on;
clr = get(h(1),'colororder');
boxplot(h(2),x,species,'orientation','horizontal',...
     'label',{'','',''},'color',clr);
boxplot(h(3),y,species,'orientation','horizontal',...
     'label', {'','',''},'color',clr);
set(h(2:3),'XTickLabel','');
view(h(3),[270,90]);  % Rotate the Y plot
axis(h(1),'auto');  % Sync axes
hold off;

Create a scatterhist Plot in a Specified Parent Container

Load the sample data. Create data vector x from the first column of the data matrix, which contains sepal length measurements from iris flowers. Create data vector y from the second column of the data matrix, which contains sepal width measurements from the same flowers.

load fisheriris
x = meas(:,1);
y = meas(:,2);

Create a new figure and define two uipanel objects to divide the figure into two parts. In the upper half of the figure, plot the sample data using scatterhist. Include marginal kernel density plots grouped by species. In the lower half of the figure, plot a histogram of the sepal length measurements contained in x.

figure
hp1 = uipanel('position',[0 .5 1 .5]);
hp2 = uipanel('position',[0 0 1 .5]);
scatterhist(x,y,'Group',species,'Kernel','on','Parent',hp1);
axes('Parent',hp2);
hist(x);

Input Arguments

x — Sample data

vector

Sample data, specified as a vector. The data vectors x and y must be the same length.

If x or y contain NaN values, then scatterhist:

• Removes rows with NaN values in either x or y from both data vectors when generating the scatter plot

• Removes rows with NaN values only from the corresponding x or y data vector when generating the marginal histograms

Data Types: single | double

y — Sample data

vector

Sample data, specified as a vector. The data vectors x and y must be the same length.

If x or y contain NaN values, then scatterhist:

• Removes rows with NaN values in either x or y from both data vectors when generating the scatter plot

• Removes rows with NaN values only from the corresponding x or y data vector when generating the marginal histograms

Data Types: single | double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: 'Location','SouthEast','Direction','out' specifies a plot with histograms located below and to the right of the scatter plot, with the bars directed away from the scatter plot.

NBins — Number of bins for histograms

positive integer value | vector

Number of bins for histograms, specified as the comma-separated pair consisting of 'NBins' and a positive integer value greater than or equal to 2, or vector of two such values. If the number of bins is specified as a positive integer value, that value is the number of bins for both the x and y histograms. If the number of bins is specified by a vector, the first value is the number of bins for the x data, and the second value is the number of bins for the y data. By default, the number of bins is computed based on the sample standard deviation using Scott’s rule.

Example: 'NBins',[5,7]

Data Types: single | double

Location — Location of marginal histograms

'SouthWest' (default) | 'SouthEast' | 'NorthEast' | 'NorthWest'

Location of the marginal histograms in the figure, specified as the comma-separated pair consisting of 'Location' and one of the following.

'SouthWest'	Plot the histograms below and to the left of the scatter plot.
'SouthEast'	Plot the histograms below and to the right of the scatter plot.
'NorthEast'	Plot the histograms above and to the right of the scatter plot.
'NorthWest'	Plot the histograms above and to the left of the scatter plot.

Example: 'Location','SouthEast'

Direction — Direction of marginal histograms

'in' (default) | 'out'

Direction of the marginal histograms, specified as the comma-separated pair consisting of 'Direction' and one of the following.

'in'	Plot the histograms with the bars directed toward the scatter plot.
'out'	Plot the histograms with the bars directed away from the scatter plot.

Example: 'Direction','out'

Group — Grouping variable

categorical array | logical or numeric vector | character array | string array | cell array of character vectors

Grouping variable, specified as the comma-separated pair consisting of 'Group' and a categorical array, logical or numeric vector, character array, string array, or cell array of character vectors. Each unique value in a grouping variable defines a group.

For example, if Gender is a cell array of character vectors with values 'Male' and 'Female', you can use Gender as a grouping variable to plot your data by gender.

The number of rows in the grouping variable must be equal to the length of x.

Example: 'Group',Gender

Data Types: categorical | single | double | logical | char | string | cell

PlotGroup — Grouped plot indicator

'on' | 'off'

Grouped plot indicator, specified as the comma-separated pair consisting of 'PlotGroup' and one of the following.

'on'	Display grouped histograms or grouped kernel density plots. This is the default if a Group parameter is specified.
'off'	Display histograms or kernel density plots of the whole data set. This is the default if a Group parameter is not specified.

Example: 'PlotGroup','off'

Style — Histogram display style

'stairs' | 'bar'

Histogram display style, specified as the comma-separated pair consisting of 'PlotGroup' and one of the following.

'stairs'	Display a stairstep plot that shows the outline of the histogram without filling the bars. This is the default if you specify a grouping variable that contains more than one group.
'bar'	Display a histogram bar plot. This is the default if you specify a grouping variable that contains only one group or if PlotGroup is specified as 'off'.

Example: 'Style','bar'

Kernel — Kernel density plot indicator

'off' (default) | 'on' | 'overlay'

Kernel density plot indicator, specified as the comma-separated pair consisting of 'Kernel' and one of the following.

'off'	Display the marginal distributions as histograms.
'on'	Display the marginal distributions as kernel density plots.
'overlay'	Display the marginal distributions as kernel density plots overlaid onto histograms, similar to histfit.

Example: 'Kernel','overlay'

Bandwidth — Bandwidth of kernel smoothing window

matrix

Bandwidth of kernel smoothing window, specified as the comma-separated pair consisting of 'Bandwidth' and a matrix of size 2-by-K, where K is the number of unique groups. The first row of the matrix gives the bandwidth of each group in x, and the second row gives the bandwidth of each group in y. By default, scatterhist finds the optimal bandwidth for estimating normal densities. Specifying a different bandwidth value changes the smoothing characteristics of the resulting kernel density plot. The value specified is a scaling factor for the normal distribution used to generate the kernel density plot.

Example: 'Bandwidth',[.5,.2,.1;.15,.25,.35]

Data Types: single | double

Legend — Legend visibility indicator

'on' | 'off'

Legend visibility indicator, specified as the comma-separated pair consisting of 'Legend' and one of the following.

'on'	Set legend visible. This is the default if a Group parameter is specified.
'off'	Set legend invisible. This is the default if a Group parameter is not specified.

Example: 'Legend','on'

Parent — Parent container of the plot

uipanel container object | figure container object

Parent container for the plot, specified as a uipanel container object or figure container object. You can create panel container objects using uipanel or figure, respectively.

For example, if h1 is a panel container object, specify the parent container of the plot as follows.

Example: 'Parent',h1

LineStyle — Style of kernel density plot line

valid line style | string array or cell array of line styles

Style of kernel density plot line, specified as the comma-separated pair consisting of 'LineStyle' and a valid line style or a string array or cell array of valid line styles. See plot for valid line styles. The default is a solid line. Use a string array or cell array to specify different line styles for each group. When the total number of groups exceeds the number of specified values, scatterhist cycles through the specified values.

Example: 'LineStyle',{'-',':','-.'}

Data Types: char | string | cell

LineWidth — Width of kernel density plot line

0.5 (default) | nonnegative scalar value | vector

Width of kernel density plot line, specified as the comma-separated pair consisting of 'LineWidth' and a nonnegative scalar value or vector of nonnegative scalar values. The specified value is the size of the kernel density plot line measured in points. The default size is 0.5 points. Use a vector to specify different line widths for each group. When the total number of groups is greater than the number of specified values, scatterhist cycles through the specified values.

Example: 'LineWidth',[0.5,1,2]

Data Types: single | double

Color — Marker color for each scatter plot group

character vector or string scalar of color names | matrix of RGB values

Marker color for each scatter plot group, specified as the comma-separated pair consisting of 'Color' and a character vector or string scalar of color names, or a three-column matrix of RGB values in the range [0,1]. If you specify colors using a matrix, then each row of the matrix is an RGB triplet that represents a group. The three columns of the matrix represent the R value, G value, and B value, respectively. When the total number of groups exceeds the number of specified colors, scatterhist cycles through the specified colors.

This table lists the predefined colors and their equivalent RGB triplet values.

Option	Description	Equivalent RGB Triplet
'red' or 'r'	Red	[1 0 0]
'green' or 'g'	Green	[0 1 0]
'blue' or 'b'	Blue	[0 0 1]
'yellow' or 'y'	Yellow	[1 1 0]
'magenta' or 'm'	Magenta	[1 0 1]
'cyan' or 'c'	Cyan	[0 1 1]
'white' or 'w'	White	[1 1 1]
'black' or 'k'	Black	[0 0 0]

Example: 'Color','kcm'

Example: 'Color',[.5,0,1;0,.5,.5]

Data Types: single | double | char | string

Marker — Marker symbol for each scatterplot group

'o' (default) | character vector | string scalar

Marker symbol for each scatter plot group, specified as the comma-separated pair consisting of 'Marker' and a character vector or string scalar of one or more valid marker symbols. See plot for valid symbols. The default is 'o', a circle. When the total number of groups exceeds the number of specified symbols, scatterhist cycles through the specified symbols.

Example: 'Marker','+do'

Data Types: char | string

MarkerSize — Marker size for each scatter plot group

6 (default) | nonnegative scalar value | vector

Marker size for each scatter plot group, specified as the comma-separated pair consisting of 'MarkerSize' and a nonnegative scalar value or a vector of nonnegative scalar values, measured in points. When the total number of groups exceeds the number of specified values, scatterhist cycles through the specified values.

Example: 'MarkerSize',10

Data Types: single | double

Output Arguments

h — Axes handles

vector

Axes handles for the three plots, returned as a vector. The vector contains the handles for the scatter plot, the histogram along the horizontal axis, and the histogram along the vertical axis, respectively.

Alternative Functionality

Alternatively, you can create a ScatterHistogramChart object by using the scatterhistogram function.

• Explore the data interactively in the object by panning, zooming, and using data tips. Unlike the scatterhist function, scatterhistogram updates the marginal histograms based on the data within the current scatter plot limits.

• Control the appearance and behavior of the scatter histogram chart by changing the ScatterHistogramChart Properties.

Version History

Introduced in R2007a