gscatter

Scatter plot by group

Syntax

gscatter(x,y,g)

gscatter(x,y,g,clr,sym,siz)

gscatter(x,y,g,clr,sym,siz,doleg)

gscatter(x,y,g,clr,sym,siz,doleg,xnam,ynam)

gscatter(ax,___)

gscatter(___,"filled")

h = gscatter(___)

Description

gscatter(x,y,g) creates a scatter plot of x and y, grouped by g. The inputs x and y are vectors of the same size.

gscatter(x,y,g,clr,sym,siz) specifies the marker color clr, symbol sym, and size siz for each group.

gscatter(x,y,g,clr,sym,siz,doleg) controls whether a legend is displayed on the graph. gscatter creates a legend by default.

gscatter(x,y,g,clr,sym,siz,doleg,xnam,ynam) specifies the names to use for the x-axis and y-axis labels. If you do not provide xnam and ynam, and the x and y inputs are variables with names, then gscatter labels the axes with the variable names.

gscatter(ax,___) uses the plot axes specified by the axes object ax. Specify ax as the first input argument followed by any of the input argument combinations in the previous syntaxes.

gscatter(___,"filled") fills in marker interiors. gscatter ignores this option for markers that do not have interiors.

h = gscatter(___) returns graphics handles corresponding to the groups in g.

You can pass in [] for clr, sym, and siz to use their default values.

Examples

Scatter Plot with Default Settings

Load the carsmall data set.

load carsmall

Plot the Displacement values on the x-axis and the Horsepower values on the y-axis. gscatter uses the variable names as the default labels for the axes. Group the data points by Model_Year.

gscatter(Displacement,Horsepower,Model_Year)

Scatter Plot with One Grouping Variable

Load the discrim data set.

load discrim

The data set contains ratings of cities according to nine factors such as climate, housing, education, and health. The matrix ratings contains the ratings information.

Plot the relationship between the ratings for climate (first column) and housing (second column) grouped by city size in the matrix group. Choose different colors and plotting symbols for each group.

gscatter(ratings(:,1),ratings(:,2),group,'br','xo')
xlabel('climate')
ylabel('housing')

Scatter Plot with Multiple Grouping Variables

Load the hospital data set.

load hospital

Plot the ages and weights of the hospital patients. Group the patients according to their gender and smoker status. Use the o symbol to represent nonsmokers and the * symbol to represent smokers.

x = hospital.Age;
y = hospital.Weight;
g = {hospital.Sex,hospital.Smoker};
gscatter(x,y,g,'rkgb','o*',8,'on','Age','Weight')
legend('Location','northeastoutside')

Specify Axes for Scatter Plot

Load the carsmall data set. Create a figure with two subplots and return the axes objects as ax1 and ax2. Create a scatter plot in each set of axes by referring to the corresponding Axes object. In the left subplot, group the data using the Model_Year variable. In the right subplot, group the data using the Cylinders variable. Add a title to each plot by passing the corresponding Axes object to the title function.

load carsmall
color = lines(6); % Generate color values

ax1 = subplot(1,2,1); % Left subplot
gscatter(ax1,Acceleration,MPG,Model_Year,color(1:3,:))
title(ax1,'Left Subplot (Model Year)')

ax2 = subplot(1,2,2); % Right subplot
gscatter(ax2,Acceleration,MPG,Cylinders,color(4:6,:))
title(ax2,'Right Subplot (Cylinders)')

Specify Marker Colors

Specify marker colors using the colormap determined by the hsv function.

Load the Lidar scan data set which contains the coordinates of objects surrounding a vehicle, stored as a collection of 3-D points.

load('lidar_subset.mat') 
loc = lidar_subset;

To highlight the environment around the vehicle, set the region of interest to span 20 meters to the left and right of the vehicle, 20 meters in front and back of the vehicle, and the area above the surface of the road.

xBound = 20; % in meters
yBound = 20; % in meters
zLowerBound = 0; % in meters

Crop the data to contain only points within the specified region.

indices = loc(:,1) <= xBound & loc(:,1) >= -xBound ...
    & loc(:,2) <= yBound & loc(:,2) >= -yBound ...
    & loc(:,3) > zLowerBound;
loc = loc(indices,:);

Cluster the data by using dbscan with pairwise distances.

D = pdist2(loc,loc);
idx = dbscan(D,2,50,'Distance','precomputed');

Visualize the resulting clusters as a 2-D group scatter plot by using the gscatter function. By default, gscatter uses the seven MATLAB default colors. If the number of unique clusters exceeds seven, the function cycles through the default colors as needed. Find the number of clusters, and generate the corresponding number of colors by using the hsv function. Specify marker colors to use a unique color for each cluster.

numGroups = length(unique(idx));
clr = hsv(numGroups);
gscatter(loc(:,1),loc(:,2),idx,clr)
xlabel('x')
ylabel('y')

Create and Modify Scatter Plot

Load the carbig data set.

load carbig

Create a scatter plot comparing Acceleration to MPG. Group data points based on Origin.

h = gscatter(Acceleration,MPG,Origin)

h = 
  7x1 Line array:

  Line    (USA)
  Line    (France)
  Line    (Japan)
  Line    (Germany)
  Line    (Sweden)
  Line    (Italy)
  Line    (England)

Display the Line object corresponding to the group labeled (Japan).

jgroup = h(3)

jgroup = 
  Line (Japan) with properties:

              Color: [0.9290 0.6940 0.1250]
          LineStyle: 'none'
          LineWidth: 0.5000
             Marker: '.'
         MarkerSize: 15
    MarkerFaceColor: 'none'
              XData: [15 14.5000 14.5000 14 19 18 15.5000 13.5000 17 14.5000 16.5000 19 16.5000 13.5000 13.5000 19 21 16.5000 19 15 15.5000 16 13.5000 17 17.5000 17.4000 17 16.4000 15.5000 18.5000 16.8000 18.2000 16.4000 14.5000 ... ] (1x79 double)
              YData: [24 27 27 25 31 35 24 19 28 23 27 20 22 18 20 31 32 31 32 24 26 29 24 24 33 33 32 28 19 31.5000 33.5000 26 30 22 21.5000 32.8000 39.4000 36.1000 27.5000 27.2000 21.1000 23.9000 29.5000 34.1000 31.8000 38.1000 ... ] (1x79 double)

  Use GET to show all properties

Change the marker color for the Japan group to black.

jgroup.Color = 'k';

Input Arguments

x — x-axis values

numeric vector

x-axis values, specified as a numeric vector. x must have the same size as y.

Data Types: single | double

y — y-axis values

numeric vector

y-axis values, specified as a numeric vector. y must have the same size as x.

Data Types: single | double

g — Grouping variable

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

Grouping variable, specified as a categorical vector, logical vector, numeric vector, character array, string array, or cell array of character vectors. Alternatively, g can be a cell array containing several grouping variables (such as {g1 g2 g3}), in which case observations are in the same group if they have common values of all grouping variables. Points in the same group appear on the scatter plot with the same marker color, symbol, and size.

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

Example: species

Example: {Cylinders,Origin}

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

clr — Marker colors

MATLAB^® default colors (default) | character vector or string scalar of short color names | matrix of RGB triplets

Marker colors, specified as a character vector or string scalar of short color names or a matrix of RGB triplets.

For a custom color, specify a matrix of RGB triplets. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1]; for example, [0.4 0.6 0.7].

Alternatively, you can specify some common colors by name. This table lists the named color options and the equivalent RGB triplets

Short Name	RGB Triplet	Appearance
'r'	[1 0 0]
'g'	[0 1 0]
'b'	[0 0 1]
'c'	[0 1 1]
'm'	[1 0 1]
'y'	[1 1 0]
'k'	[0 0 0]
'w'	[1 1 1]

Here are the RGB triplet color codes for the default colors MATLAB uses in many types of plots.

RGB Triplet	Appearance
[0 0.4470 0.7410]
[0.8500 0.3250 0.0980]
[0.9290 0.6940 0.1250]
[0.4940 0.1840 0.5560]
[0.4660 0.6740 0.1880]
[0.3010 0.7450 0.9330]
[0.6350 0.0780 0.1840]

The default value for clr is the matrix of RGB triplets containing the MATLAB default colors.

If you do not specify enough colors for all unique groups in g, then gscatter cycles through the specified values in clr. If you use default values when the number of unique groups exceeds the number of default colors (7), then gscatter cycles through the default values as needed.

Example: 'rgb'

Example: [0 0 1; 0 0 0]

Data Types: char | string | single | double

sym — Marker symbols

'.' (default) | character vector or string scalar of symbols

Marker symbols, specified as a character vector or string scalar of symbols recognized by the plot function. This table lists the available marker symbols.

Value	Description
'o'	Circle
'+'	Plus sign
'*'	Asterisk
'.'	Point
'x'	Cross
's'	Square
'd'	Diamond
'^'	Upward-pointing triangle
'v'	Downward-pointing triangle
'>'	Right-pointing triangle
'<'	Left-pointing triangle
'p'	Five-pointed star (pentagram)
'h'	Six-pointed star (hexagram)
'n'	No markers

If you do not specify enough values for all groups, then gscatter cycles through the specified values as needed.

Example: 'o+*v'

Data Types: char | string

siz — Marker sizes

positive numeric vector

Marker sizes, specified as a positive numeric vector in points. The default value is determined by the number of observations. If you do not specify enough values for all groups, then gscatter cycles through the specified values as needed.

Example: [6 12]

Data Types: single | double

doleg — Option to include legend

'on' (default) | 'off'

Option to include a legend, specified as either 'on' or 'off'. By default, the legend is displayed on the graph.

xnam — x-axis label

x variable name (default) | character vector | string scalar

x-axis label, specified as a character vector or string scalar.

Data Types: char | string

ynam — y-axis label

y variable name (default) | character vector | string scalar

y-axis label, specified as a character vector or string scalar.

Data Types: char | string

"filled" — Option to fill interior of markers

"filled"

Option to fill the interior of markers, specified as "filled". Use this option with markers that have an interior, such as "o" and "s". gscatter ignores "filled" for markers that do not have an interior, such as "." and "+".

Data Types: string

ax — Axes for plot

Axes object | UIAxes object

Axes for the plot, specified as an Axes or UIAxes object. If you do not specify ax, then gscatter creates the plot using the current axes. For more information on creating an axes object, see axes and uiaxes.

Output Arguments

h — Graphics handles

array of Line objects

Graphics handles, returned as an array of Line objects. Each Line object corresponds to one of the groups in g. You can use dot notation to query and set properties of the line objects. For a list of Line object properties, see Line Properties.

Version History

Introduced before R2006a

R2022a: gscatter uses the MATLAB default color scheme

Starting in R2022a, the gscatter function uses the MATLAB default color scheme to determine marker colors, following the order specified in the ColorOrder property of the axes.

In previous releases, the gscatter function uses the colormap returned by the hsv function. If you want to determine marker colors using the hsv colormap, specify marker colors (fourth input argument of gscatter) as hsv(numGroups), where numGroups is the number of unique group combinations in the grouping variables.

If you use the new default color scheme and the number of unique groups exceeds the number of default colors (7), then gscatter cycles through the default values as needed. If you want to use different colors for different groups, specify the marker colors as hsv(numGroups). For an example, see Specify Marker Colors.