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swarmchart

Swarm scatter chart

  • Swarm chart

Description

Vector and Matrix Data

example

swarmchart(x,y) displays a swarm chart, which is a scatter plot with the points offset (jittered) in the x-dimension. The points form distinct shapes, and the outline of each shape is similar to a violin plot. Swarm charts help you to visualize discrete x data with the distribution of the y data. At each location in x, the points are jittered based on the kernel density estimate of y.

  • To plot one set of points, specify x and y as vectors of equal length.

  • To plot multiple sets of points on the same set of axes, specify at least one of x or y as a matrix.

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swarmchart(x,y,sz) specifies the marker sizes. To plot all the markers with the same size, specify sz as a scalar. To plot the markers with different sizes, specify sz as a vector or a matrix.

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swarmchart(x,y,sz,c) specifies the marker colors. You can specify one color for all the markers, or you can vary the color. For example, you can plot all red circles by specifying c as 'red'.

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swarmchart(___,mkr) specifies a different marker than the default marker, which is a circle. Specify mkr after all the arguments in any of the previous syntaxes.

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swarmchart(___,'filled') fills in the markers. Specify the 'filled' option after all the arguments in any of the previous syntaxes.

Table Data

example

swarmchart(tbl,xvar,yvar) plots the variables xvar and yvar from the table tbl. To plot one data set, specify one variable for xvar and one variable for yvar. To plot multiple data sets, specify multiple variables for xvar, yvar, or both. If both arguments specify multiple variables, they must specify the same number of variables.

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swarmchart(tbl,xvar,yvar,'filled') plots the specified variables and fills in the markers.

Additional Options

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swarmchart(ax,___) displays the swarm chart in the target axes. Specify the axes before all the arguments in any of the previous syntaxes.

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swarmchart(___,Name,Value) specifies additional properties for the swarm chart using one or more name-value arguments. Specify the properties after all other input arguments. For example:

  • swarmchart(x,y,'LineWidth',2) creates a swarm chart with 2-point marker outlines.

  • swarmchart(tbl,'MyX','MyY','ColorVariable','MyColors') creates a swarm chart from data in a table, and customizes the marker colors using data from the table.

For a list of properties, see Scatter Properties.

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s = swarmchart(___) returns the Scatter object or an array of Scatter objects. Use s to modify properties of the chart after creating it. For a list of properties, see Scatter Properties.

Examples

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Create a vector of x coordinates, and use the randn function to generate normally distributed random values for y. Then create a swarm chart of x and y.

x = [ones(1,500) 2*ones(1,500) 3*ones(1,500)];
y1 = 2 * randn(1,500);
y2 = 3 * randn(1,500) + 5;
y3 = 5 * randn(1,500) + 5;
y = [y1 y2 y3];
swarmchart(x,y)

Figure contains an axes object. The axes object contains an object of type scatter.

Create three sets of x and y coordinates. Use the randn function to generate random values for y.

x1 = ones(1,500);
x2 = 2 * ones(1,500);
x3 = 3 * ones(1,500);
y1 = 2 * randn(1,500);
y2 = [randn(1,250) randn(1,250) + 4];
y3 = 5 * randn(1,500) + 5;

Create a swarm chart of the first data set, and specify a uniform marker size of 5. Then call hold on to plot the second and third data sets together with the first data set. Call hold off to release the hold state of the axes.

swarmchart(x1,y1,5)
hold on
swarmchart(x2,y2,5)
swarmchart(x3,y3,5)
hold off

Figure contains an axes object. The axes object contains 3 objects of type scatter.

Read the BicycleCounts.csv data set into a timetable called tbl. This data set contains bicycle traffic data over a period of time. Display the first five rows of tbl.

tbl = readtable(fullfile(matlabroot,'examples','matlab','data','BicycleCounts.csv'));
tbl(1:5,:)
ans=5×5 table
         Timestamp              Day         Total    Westbound    Eastbound
    ___________________    _____________    _____    _________    _________

    2015-06-24 00:00:00    {'Wednesday'}     13          9            4    
    2015-06-24 01:00:00    {'Wednesday'}      3          3            0    
    2015-06-24 02:00:00    {'Wednesday'}      1          1            0    
    2015-06-24 03:00:00    {'Wednesday'}      1          1            0    
    2015-06-24 04:00:00    {'Wednesday'}      1          1            0    

Create a vector x with the day name from each observation, and another vector y with the bicycle traffic observed. Then create a swarm chart of x and y, and specify the point marker ('.'). The chart shows the distribution of bicycle traffic according to the day of the week.

daynames = ["Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"];
x = categorical(tbl.Day,daynames);
y = tbl.Total;
swarmchart(x,y,'.');

Figure contains an axes object. The axes object contains an object of type scatter.

Read the BicycleCounts.csv data set into a timetable called tbl. Create a vector x with the day name for each observation, another vector y with the bicycle traffic observed, and a third vector c with the hour of the day.

Then create a swarm chart of x and y, and specify the marker size as 20. Specify the colors of the markers as vector c. The values in the vector index into the figure's colormap. Thus, the colors change according to the hour for each data point. Use the 'filled' option to fill the markers with color instead of displaying them as hollow circles.

tbl = readtable(fullfile(matlabroot,'examples','matlab','data','BicycleCounts.csv'));
daynames = ["Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"];
x = categorical(tbl.Day,daynames);
y = tbl.Total;
c = hour(tbl.Timestamp);
swarmchart(x,y,20,c,'filled');

Figure contains an axes object. The axes object contains an object of type scatter.

Read the BicycleCounts.csv data set into a timetable called tbl. Create a vector x with the day name for each observation, another vector y with the bicycle traffic observed, and a third vector c with the hour of the day. Then create a swarm chart of x and y, and specify the marker size as 5, and the colors of the markers as vector c. Call the swarmchart function with the return argument s, so that you can modify the chart after creating it.

tbl = readtable(fullfile(matlabroot,'examples','matlab','data','BicycleCounts.csv'));
daynames = ["Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"];
x = categorical(tbl.Day,daynames);
y = tbl.Total;
c = hour(tbl.Timestamp);
s = swarmchart(x,y,5,c);

Figure contains an axes object. The axes object contains an object of type scatter.

Change the shapes of the clusters at each x location, so that the points are uniformly and randomly distributed and the spacing is limited to no more than 0.5 data units.

s.XJitter = 'rand';
s.XJitterWidth = 0.5;

Figure contains an axes object. The axes object contains an object of type scatter.

Create a pair of x and y coordinates. Use the randn function to generate random values for y. Then create a swarm chart with filled markers that are 50% transparent both on their faces and on their edges.

x1 = ones(1,500);
x2 = 2 * ones(1,500);
x = [x1 x2];
y1 = 2 * randn(1,500);
y2 = [randn(1,250) randn(1,250) + 4];
y = [y1 y2];
swarmchart(x,y,'filled','MarkerFaceAlpha',0.5,'MarkerEdgeAlpha',0.5)

Figure contains an axes object. The axes object contains an object of type scatter.

A convenient way to plot data from a table is to pass the table to the swarmchart function and specify the variables you want to plot. For example, create a table with three variables of random numbers, and plot the X and Y1 variables. By default, the axis labels match the variable names.

tbl = table(randi(2,100,1),randn(100,1),randn(100,1)+10, ...
   'VariableNames',{'X','Y1','Y2'});

swarmchart(tbl,'X','Y1')

Figure contains an axes object. The axes object contains an object of type scatter.

You can also plot multiple variables at the same time. For example, plot the Y1 and Y2 variables on the y-axis by specifying the yvar argument as the cell array {'Y1','Y2'}. Then add a legend. The legend labels match the variable names.

swarmchart(tbl,'X',{'Y1','Y2'})
legend

Figure contains an axes object. The axes object contains 2 objects of type scatter.

One way to plot data from a table and customize the colors and marker sizes is to set the ColorVariable and SizeData properties. You can set these properties as name-value arguments when you call the swarmchart function, or you can set them on the Scatter object later.

For example, create a table with three variables of random numbers, and plot the X and Y variables with filled markers. Vary the marker colors by specifying the ColorVariable name-value argument. Return the Scatter object as s, so you can set other properties later.

tbl = table(randi(2,100,1),randn(100,1),randn(100,1), ...
   'VariableNames',{'X','Y','Colors'});

s = swarmchart(tbl,'X','Y','filled','ColorVariable','Colors');

Figure contains an axes object. The axes object contains an object of type scatter.

Change the marker sizes to 100 points by setting the SizeData property.

s.SizeData = 100;

Figure contains an axes object. The axes object contains an object of type scatter.

Read the BicycleCounts.csv data set into a timetable called tbl. This data set contains bicycle traffic data over a period of time. Display the first five rows of tbl.

tbl = readtable(fullfile(matlabroot,'examples','matlab','data','BicycleCounts.csv'));
tbl(1:5,:)
ans=5×5 table
         Timestamp              Day         Total    Westbound    Eastbound
    ___________________    _____________    _____    _________    _________

    2015-06-24 00:00:00    {'Wednesday'}     13          9            4    
    2015-06-24 01:00:00    {'Wednesday'}      3          3            0    
    2015-06-24 02:00:00    {'Wednesday'}      1          1            0    
    2015-06-24 03:00:00    {'Wednesday'}      1          1            0    
    2015-06-24 04:00:00    {'Wednesday'}      1          1            0    

Define x as a categorical array of the day names in the table. Define yEast and yWest as vectors containing the eastbound and westbound bicycle traffic counts.

daynames = ["Sunday" "Monday" "Tuesday" "Wednesday" "Thursday" "Friday" "Saturday"];
x = categorical(tbl.Day,daynames);
yEast = tbl.Eastbound;
yWest = tbl.Westbound;

Create a tiled chart layout in the 'flow' tile arrangement, so that the axes fill the available space in the layout. Call the nexttile function to create an axes object and return it as ax1. Then create a swarm chart of the eastbound data by passing ax1 to the swarmchart function.

tiledlayout('flow')
ax1 = nexttile;
y = tbl.Eastbound;
swarmchart(ax1,x,y,'.');

Figure contains an axes object. The axes object contains an object of type scatter.

Repeat the process to create a second axes object and a swarm chart for the westbound traffic.

ax2 = nexttile;
y = tbl.Westbound;
s = swarmchart(ax2,x,y,'.');

Figure contains 2 axes objects. Axes object 1 contains an object of type scatter. Axes object 2 contains an object of type scatter.

Input Arguments

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x-coordinates, specified as a scalar, vector, or matrix. The size and shape of x depends on the shape of your data. This table describes the most common situations.

Type of PlotHow to Specify Coordinates
Single point

Specify x and y as scalars. For example:

swarmchart(1,1)

One set of points

Specify x and y as any combination of row or column vectors of the same length. For example:

x = randi(3,100,1);
y = randn(1,100);
swarmchart(x,y)

Multiple sets of points that are different colors

If all the sets share the same x- or y-coordinates, specify the shared coordinates as a vector and the other coordinates as a matrix. The length of the vector must match one of the dimensions of the matrix. For example:

x = randi(2,1,100); 
y = [randn(100,1) randn(100,1)+5];
swarmchart(x,y,100)
If the matrix is square, swarmchart plots a separate set of points for each column in the matrix.

Alternatively, specify x and y as matrices of equal size. In this case, swarmchart plots each column of y against the corresponding column of x. For example:

x = randi(2,100,2);
y = [randn(100,1) randn(100,1)+5];
swarmchart(x,y,100)

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | categorical

y-coordinates, specified as a scalar, vector, or matrix. The size and shape of y depends on the shape of your data. This table describes the most common situations.

Type of PlotHow to Specify Coordinates
Single point

Specify x and y as scalars. For example:

swarmchart(1,1)

One set of points

Specify x and y as any combination of row or column vectors of the same length. For example:

x = randi(3,100,1);
y = randn(1,100);
swarmchart(x,y)

Multiple sets of points that are different colors

If all the sets share the same x- or y-coordinates, specify the shared coordinates as a vector and the other coordinates as a matrix. The length of the vector must match one of the dimensions of the matrix. For example:

x = randi(2,1,100); 
y = [randn(100,1) randn(100,1)+5];
swarmchart(x,y,100)
If the matrix is square, swarmchart plots a separate set of points for each column in the matrix.

Alternatively, specify x and y as matrices of equal size. In this case, swarmchart plots each column of y against the corresponding column of x. For example:

x = randi(2,100,2);
y = [randn(100,1) randn(100,1)+5];
swarmchart(x,y,100)

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | categorical | datetime | duration

Marker size, specified as a numeric scalar, vector, matrix, or empty array ([]). The size controls the area of each marker in points squared. An empty array specifies the default size of 36 points. The way you specify the size depends on how you specify x and y, and how you want the plot to look. This table describes the most common situations.

Desired Marker Sizesx and y szExample

Same size for all points

Any valid combination of vectors or matrices described for x and y.

Scalar

Specify x as a vector, y as a matrix, and sz as a scalar.

x = randi(2,1,100); 
y = randn(100,1); 
swarmchart(x,y,100)

Different size for each point

Vectors of the same length

  • A vector with the same length as x and y.

  • A matrix with at least one dimension that matches the lengths of x and y. Specifying a matrix is useful for displaying multiple markers with different sizes at each (x,y) location.

Specify x, y, and sz as vectors.

x = randi(2,1,100); 
y = randn(100,1); 
sz = randi([70 2000],100,1);
swarmchart(x,y,sz)

Specify x and y as vectors and sz as a matrix.

x = randi(2,1,100); 
y = randn(100,1); 
sz = randi([70 2000],100,2);
swarmchart(x,y,sz)

Different size for each point

At least one of x or y is a matrix for plotting multiple data sets

  • A vector with the same number of elements as there are points in each data set.

  • A matrix that has the same size as the x or y matrix.

Specify x as a vector, y as a matrix, and sz as vector.

x = randi(2,1,100);
y = [randn(100,1) randn(100,1)+5];
sz = randi([70 2000],100,1);
swarmchart(x,y,sz)

Specify x as a vector, y as a matrix, and sz as a matrix the same size as y.

x = randi(2,1,100); 
y = [randn(100,1) randn(100,1)+5]; 
sz = randi([70 2000],100,2);
swarmchart(x,y,sz)

Marker color, specified as a color name, RGB triplet, matrix of RGB triplets, or a vector of colormap indices.

  • Color name — A color name such as 'red', or a short name such as 'r'.

  • RGB triplet — 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]. RGB triplets are useful for creating custom colors.

  • Matrix of RGB triplets — A three-column matrix in which each row is an RGB triplet.

  • Vector of colormap indices — A vector of numeric values that is the same length as the x and y vectors.

The way you specify the color depends on the desired color scheme and whether you are plotting one set of coordinates or multiple sets of coordinates. This table describes the most common situations.

Color SchemeHow to Specify the ColorExample

Use one color for all the points.

Specify a color name or a short name from the table below, or specify one RGB triplet.

Plot one set of points, and specify the color as 'red'.

x = randi(2,1,100); 
y = randn(100,1); 
c = 'red';
swarmchart(x,y,[],c)

Plot two sets of points, and specify the color as red using an RGB triplet.

x = randi(2,1,100); 
y = randn(100,1); 
c = [0.6 0 0.9];
swarmchart(x,y,[],c)

Assign different colors to each point using a colormap.

Specify a row or column vector of numbers. The numbers index into the current colormap array. The smallest value maps to the first row in the colormap, and the largest value maps to the last row. The intermediate values map linearly to the intermediate rows.

If your plot has three points, specify a column vector to ensure the values are interpreted as colormap indices.

You can use this method only when x, y, and sz are all vectors.

Create a vector c that specifies 100 colormap indices. Plot 100 points using the colors from the current colormap. Then, change the colormap to winter.

x = randi(2,1,100); 
y = randn(100,1);
c = 1:100;
swarmchart(x,y,[],c)
colormap(gca,'winter')

Create a custom color for each point.

Specify an m-by-3 matrix of RGB triplets, where m is the number of points in the plot.

You can use this method only when x, y, and sz are all vectors.

Create a matrix c that specifies 100 random RGB triplets. Then create a swarm chart of 100 points using those colors.

x = randi(2,1,100); 
y = randn(100,1); 
c = rand(100,3);
swarmchart(x,y,[],c)

Create a different color for each data set.

Specify an n-by-3 matrix of RGB triplets, where n is the number of data sets.

You can use this method only when at least one of x, y, or sz is a matrix.

Create a matrix c that contains two RGB triplets. Then plot two data sets using those colors.

x = randi(2,100,2); 
y = [randn(100,1) randn(100,1)+5]; 
c = [1 0 0; 0 0 1];
swarmchart(x,y,[],c)

Color Names and RGB Triplets for Common Colors

Color NameShort NameRGB TripletHexadecimal Color CodeAppearance
'red''r'[1 0 0]'#FF0000'

Sample of the color red

'green''g'[0 1 0]'#00FF00'

Sample of the color green

'blue''b'[0 0 1]'#0000FF'

Sample of the color blue

'cyan' 'c'[0 1 1]'#00FFFF'

Sample of the color cyan

'magenta''m'[1 0 1]'#FF00FF'

Sample of the color magenta

'yellow''y'[1 1 0]'#FFFF00'

Sample of the color yellow

'black''k'[0 0 0]'#000000'

Sample of the color black

'white''w'[1 1 1]'#FFFFFF'

Sample of the color white

Here are the RGB triplets and hexadecimal color codes for the default colors MATLAB® uses in many types of plots.

RGB TripletHexadecimal Color CodeAppearance
[0 0.4470 0.7410]'#0072BD'

Sample of RGB triplet [0 0.4470 0.7410], which appears as dark blue

[0.8500 0.3250 0.0980]'#D95319'

Sample of RGB triplet [0.8500 0.3250 0.0980], which appears as dark orange

[0.9290 0.6940 0.1250]'#EDB120'

Sample of RGB triplet [0.9290 0.6940 0.1250], which appears as dark yellow

[0.4940 0.1840 0.5560]'#7E2F8E'

Sample of RGB triplet [0.4940 0.1840 0.5560], which appears as dark purple

[0.4660 0.6740 0.1880]'#77AC30'

Sample of RGB triplet [0.4660 0.6740 0.1880], which appears as medium green

[0.3010 0.7450 0.9330]'#4DBEEE'

Sample of RGB triplet [0.3010 0.7450 0.9330], which appears as light blue

[0.6350 0.0780 0.1840]'#A2142F'

Sample of RGB triplet [0.6350 0.0780 0.1840], which appears as dark red

Marker type, specified as one of the values listed in this table.

MarkerDescriptionResulting Marker
'o'Circle

Sample of circle marker

'+'Plus sign

Sample of plus sign marker

'*'Asterisk

Sample of asterisk marker

'.'Point

Sample of point marker

'x'Cross

Sample of cross marker

'_'Horizontal line

Sample of horizontal line marker

'|'Vertical line

Sample of vertical line marker

's'Square

Sample of square marker

'd'Diamond

Sample of diamond line marker

'^'Upward-pointing triangle

Sample of upward-pointing triangle marker

'v'Downward-pointing triangle

Sample of downward-pointing triangle marker

'>'Right-pointing triangle

Sample of right-pointing triangle marker

'<'Left-pointing triangle

Sample of left-pointing triangle marker

'p'Pentagram

Sample of pentagram marker

'h'Hexagram

Sample of hexagram marker

Option to fill the interior of the markers, specified as 'filled'. Use this option with markers that have a face, for example, 'o' or 'square'. Markers that do not have a face and contain only edges do not render at all ('+', '*', '.', and 'x').

The 'filled' option sets the MarkerFaceColor property of the Scatter object to 'flat' and the MarkerEdgeColor property to 'none'. In this case, MATLAB draws the marker faces, but not the edges.

Source table containing the data to plot. Specify this argument as a table or a timetable.

Table variables containing the x-coordinates, specified as one or more table variable indices.

Specifying Table Indices

Use any of the following indexing schemes to specify the desired variable or variables.

Indexing SchemeExamples

Variable names:

  • A character vector or a string scalar.

  • A cell array or string vector.

  • 'A' or "A" — A variable called A

  • {'A','B'} or ["A","B"] — Two variables called A and B

Variable numbers:

  • An index number that refers to the location of a variable in the table.

  • A vector of numbers.

  • 3 — The third variable from the table

  • [2 3] — The second and third variables from the table

Logical vector:

  • An n-element vector logical vector, where logical 1 (true) values indicate the desired variables.

  • Optionally, omit the trailing false values after the last true value.

  • [false false true false] — The third variable from an m-by-4 table

  • [false false true] — The third variable from any size table

  • [false true true] — The second and third variables from any size table

Variable type:

  • A vartype command that selects table variables of a specified type.

  • vartype('categorical') — All the variables containing categorical values

Plotting Your Data

The table variables you specify can contain numeric or categorical values.

To plot one data set, specify one variable for xvar and one variable for yvar. For example, create a table with three variables of normally distributed random values. Plot the X1 and Y variables.

tbl = table(randn(100,1),randn(100,1)+10,randn(100,1), ...
   'VariableNames',{'X1','X2','Y'});
swarmchart(tbl,'X1','Y')

To plot multiple data sets together, specify multiple variables for xvar, yvar, or both. If you specify multiple variables for both arguments, the number of variables for each argument must be the same.

For example, plot the X1 and X2 variables on the x-axis and the Y variable on the y-axis.

swarmchart(tbl,{'X1','X2'},'Y')

You can also use different indexing schemes for xvar and yvar. For example, specify xvar as a variable name and yvar as an index number.

swarmchart(tbl,'X1',3)

Table variables containing the y-coordinates, specified as one or more table variable indices.

Specifying Table Indices

Use any of the following indexing schemes to specify the desired variable or variables.

Indexing SchemeExamples

Variable names:

  • A character vector or a string scalar.

  • A cell array or string vector.

  • 'A' or "A" — A variable called A

  • {'A','B'} or ["A","B"] — Two variables called A and B

Variable numbers:

  • An index number that refers to the location of a variable in the table.

  • A vector of numbers.

  • 3 — The third variable from the table

  • [2 3] — The second and third variables from the table

Logical vector:

  • An n-element vector logical vector, where logical 1 (true) values indicate the desired variables.

  • Optionally, omit the trailing false values after the last true value.

  • [false false true false] — The third variable from an m-by-4 table

  • [false false true] — The third variable from any size table

  • [false true true] — The second and third variables from any size table

Variable type:

  • A vartype command that selects table variables of a specified type.

  • vartype('categorical') — All the variables containing categorical values

Plotting Your Data

The table variables you specify can contain numeric, categorical, datetime, or duration values.

To plot one data set, specify one variable for xvar and one variable for yvar. For example, create a table with three variables of normally distributed random values. Plot the X1 and Y variables.

tbl = table(randn(100,1),randn(100,1)+10,randn(100,1), ...
   'VariableNames',{'X1','X2','Y'});
swarmchart(tbl,'X1','Y')

To plot multiple data sets together, specify multiple variables for xvar, yvar, or both. If you specify multiple variables for both arguments, the number of variables for each argument must be the same.

For example, plot the X1 and X2 variables on the x-axis and the Y variable on the y-axis.

swarmchart(tbl,{'X1','X2'},'Y')

You can also use different indexing schemes for xvar and yvar. For example, specify xvar as a variable name and yvar as an index number.

swarmchart(tbl,'X1',3)

Target axes, specified as an Axes object, a PolarAxes object, or a GeographicAxes object. If you do not specify the axes, MATLAB plots into the current axes, or it creates an Axes object if one does not exist.

Name-Value Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: swarmchart(randi(4,500,1),randn(500,1),'MarkerFaceColor','red') specifies red filled markers.

Note

The properties listed here are only a subset. For a complete list, see Scatter Properties.

Type of jitter (spacing of points) along the x-dimension, specified as one of the following values:

  • 'none' — Do not jitter the points.

  • 'density' — Jitter the points using the kernel density estimate of y for 2-D charts. If you specify this option in two dimensions for a 3-D chart, the points are jittered based on the kernel density estimate in the third dimension. For example, setting XJitter and YJitter to 'density' uses the kernel density estimate of z.

  • 'rand' — Jitter the points randomly with a uniform distribution.

  • 'randn' — Jitter points randomly with a normal distribution.

Maximum amount of jitter (offset between points) along the x-dimension, specified as a nonnegative scalar value in data units.

For example, to set the jitter width to 90% of the shortest distance between adjacent points, take the minimum distance between unique values of x and scale by 0.9.

XJitterWidth = 0.9 * min(diff(unique(x)));

Table variable containing the color data, specified as a variable index into the source table.

Specifying the Table Index

Use any of the following indexing schemes to specify the desired variable.

Indexing SchemeExamples

Variable name:

A character vector or a string scalar.

  • 'A' or "A" — A variable called A

Variable number:

An index number that refers to the location of a variable in the table.

  • 3 — The third variable from the table

Logical vector:

  • An n-element vector logical vector, where logical 1 (true) values indicate the desired variable.

  • Optionally, omit the trailing false values after the true value.

  • [false false true false] — The third variable from an m-by-4 table

  • [false false true] — The third variable from any size table

Variable type:

A vartype command that selects table variables of a specified type.

  • vartype('double') — The variable containing double values

Specifying Color Data

Specifying the ColorVariable property controls the colors of the markers. The data in the variable controls the marker fill color when the MarkerFaceColor property is set to 'flat'. The data can also control the marker outline color, when the MarkerEdgeColor is set to 'flat'.

The table variable you specify can contain values of any numeric type. The values can be in either of the following forms:

  • A column of numbers that linearly map into the current colormap.

  • A three-column array of RGB triplets. RGB triplets are three-element vectors whose values specify the intensities of the red, green, and blue components of specific colors. The intensities must be in the range [0,1]. For example, [0.5 0.7 1] specifies a shade of light blue.

When you set the ColorVariable property, MATLAB updates the CData property.

Algorithms

The points in a swarm chart are jittered using uniform random values that are weighted by the Gaussian kernel density estimate of y and the relative number of points at each x location. This behavior corresponds to the default 'density' setting of the XJitter property on the Scatter object when you call the swarmchart function.

The maximum spread of points at each x location is 90% of the smallest distance between adjacent x values by default:

spread = 0.9 * min(diff(unique(x)));

You can control the spread by setting the XJitterWidth property on the Scatter object.

Introduced in R2020b