# spmplot

spmplot produces an interactive scatterplot matrix with boxplots or histograms on the main diagonal and possibly robust bivariate contours

## Syntax

• H=spmplot(Y)example
• H=spmplot(Y,Name,Value)example
• [H,AX]=spmplot(___)example
• [H,AX,BigAx]=spmplot(___)example

## Description

 H =spmplot(Y) Call of spmplot with Y as table.

 H =spmplot(Y, Name, Value) Call of spmplot without name/value pairs.

 [H, AX] =spmplot(___) Call of spmplot without name/value pairs (2nd example).

 [H, AX, BigAx] =spmplot(___) Call of spmplot with name/value pairs and specifying overlay, also discarding some groups with the field include, and changing the default colormap.

## Examples

expand all

### Call of spmplot with Y as table.

In this case the VariableNames of the table are added at the margins of the plot.

load fisheriris;
meastable=array2table(meas,'VariableNames',{'SL','SW','PL','PW'});
spmplot(meastable)

### Call of spmplot without name/value pairs.

Iris data: scatter plot matrix with univariate boxplots on the main diagonal.

close all
plo=struct;
plo.nameY={'SL','SW','PL','PW'};
figure;
spmplot(meas,species,plo,'hist');

### Call of spmplot without name/value pairs (2nd example).

With this way of calling spmplot just the first 4 arguments are considered. All the rest is discarded. A message appears to alert the user that this is the case.

close all
plo=struct;
plo.nameY={'SL','SW','PL','PW'};
figure;
spmplot(meas,species,plo,'hist','tag','dfgdfg');

### Call of spmplot with name/value pairs and specifying overlay, also discarding some groups with the field include, and changing the default colormap.

% The Tag setting will be used in the next example to demonstrate the
% undock option.
% Iris data: scatter plot matrix with univariate boxplots on the main
% diagonal.
close all
plo=struct;
plo.nameY={'SL','SW','PL','PW'};
spmplot(meas,'group',species,'plo',plo,'dispopt','box');
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','box','overlay','ellipse');
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','box','overlay','contour');
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','box','overlay','contourf');
set(gcf,'Tag','newTag')
cascade

## Related Examples

expand all

### Call of spmplot with name/value pairs and specifying overlay and undock.

The latter argument requires to change the tag of the scatterplot matrix not to delete.

% This example uses a matrix of logicals to set the undocked panels
plo=struct;
plo.nameY={'SL','SW','PL','PW'};
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','hist','undock',logical(eye(size(meas,2))));
% This example uses a matrix n x 2 to set the undocked panels
close all;
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','box','overlay','boxplotb','undock',[1,3;2,4]);
cascade

### Call of spmplot with name/value pairs and additional options for overlay, specifying densities just for one group.

% Iris data: scatter plot matrix with univariate boxplots on the main
% diagonal.
close all
plo=struct;
plo.nameY={'SL','SW','PL','PW'};
over = struct;
over.type = 'contourf';
over.include = logical([1 0 0]);
over.cmap = summer;
figure
spmplot(meas,'group',species,'plo',plo,'dispopt','box','overlay',over);

### Iris data: scatter plot matrix with univariate boxplots on the main diagonal and personalized options for symbols, colors, symbol size and no legend.

close all;
plo=struct;
plo.nameY={'SL','SW','PL','PW'}; % Name of the variables
plo.clr='kbr'; % Colors of the groups
plo.sym={'+' '+' 'v'}; % Symbols of the groups (inside a cell)
% Symbols can also be specified as characters
% plo.sym='++v'; % Symbols of the groups
plo.siz=3.4; % Symbol size
plo.doleg='off'; % Remove the legend
figure
spmplot(meas,species,plo,'box');

### Example of spmplot called by routine FSM.

Generate contaminated data.

close all;
state=100;
randn('state', state);
n=200;
Y=randn(n,3);
Ycont=Y;
Ycont(1:5,:)=Ycont(1:5,:)+3;
% spmplot is called automatically by all outlier detection methods, e.g. FSM
[out]=FSM(Ycont,'plots',1);

### Now test the direct use of FSM.

Set two groups, e.g. those obtained from FSM.

% Generate contaminated data
state=100;
randn('state', state);
n=200;
Y=randn(n,3);
Ycont=Y;
Ycont(1:5,:)=Ycont(1:5,:)+3;
close all;
[out]=FSM(Ycont,'plots',1);
group = zeros(n,1);
group(out.outliers)=1;
plo=struct;
% By default, the legend identifies the groups with the identifiers
% given in vector 'group'.
figure;
plo.clr = 'br';
spmplot(Ycont,group,plo,'box');

### spm with personalized tags.

With two groups, and if the Tag of the figure contains the word 'outlier', the legend will identify one group for outliers and the other for normal units. The largest number in the 'group' variable identifies the group of outliers.

close all
state=100;
randn('state', state);
n=200;
Y=randn(n,3);
Ycont=Y;
Ycont(1:5,:)=Ycont(1:5,:)+3;
[out]=FSM(Ycont,'plots',1);
group = zeros(n,1);
group(out.outliers)=1;
plo=struct;
figure('tag','This is a scatterplot with ouTliErs'); % case insensitive
spmplot(Ycont,group);
% If the Tag of the Figure contains the string 'group', then the
% legend identifies the groups with 'Group 1', Group 2', etc.
figure('tag','This scatterplot contains groups');
spmplot(Ycont,group,plo,'box');
% If the tag figure includes the word 'brush', the legend will identify
% one group for 'Unbrushed units' and the others for 'Brushed units 1',
% 'Brushed units 2', etc.
figure('Tag','Scatterplot with brushed units');
spmplot(Ycont,group,plo);
cascade;

### An example with 5 groups.

close all
rng('default')
rng(2); n1=100;
n2=80;
n3=50;
n4=80;
n5=70;
v=5;
Y1=randn(n1,v)+5;
Y2=randn(n2,v)+3;
Y3=rand(n3,v)-2;
Y4=rand(n4,v)+2;
Y5=rand(n5,v);
group=ones(n1+n2+n3+n4+n5,1);
group(n1+1:n1+n2)=2;
group(n1+n2+1:n1+n2+n3)=3;
group(n1+n2+n3+1:n1+n2+n3+n4)=4;
group(n1+n2+n3+n4+1:n1+n2+n3+n4+n5)=5;
Y=[Y1;Y2;Y3;Y4;Y5];
spmplot(Y,group,[],'box');

### spmplot called with name/pairs.

In all previous examples spmplot was called without the name/value pairs arguments The example which follow make use of the name/value pairs arguments

close all
plo=struct;
plo.nameY={'SL','SW','PL','PW'}; % Name of the variables
plo.clr='kbr'; % Colors of the groups
plo.sym={'+' '+' 'v'}; % Symbols of the groups (inside a cell)
% Symbols can also be specified as characters
% plo.sym='++v'; % Symbols of the groups
plo.siz=3.4; % Symbol size
spmplot(meas,'group',species,'plo',plo,'dispopt','box','tag','myspm');

### Interactive example 1.

In the previous examples the first argument of spmplot was a matrix. In the two examples below the first argument is a structure which contains the fields Y and Un Example when first input argument is a structure.

% Example of use of option databrush
close all
rng(841,'shr3cong');
n=100;
v=3;
m0=v+1;
Y=randn(n,v);
% Contaminated data
Ycont=Y;
Ycont(1:5,:)=Ycont(1:5,:)+3;
[fre]=unibiv(Y);
%create an initial subset with the 3 observations with the lowest
%Mahalanobis Distance
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Ycont,bs,'plots',1);
% mmdplot(out);
figure
% 'Label' 'on' 'RemoveLabels' 'off'  enables the user to label the units in the scatterplot
% matrix once selected. Option labeladd '1' inside databrush enables to add
% the labels of the selected units in the linked malfwdplot
spmplot(out,'databrush',{'persist','on','selectionmode' 'Rect', ...
'Label' 'on' 'RemoveLabels' 'off'  'labeladd','1'},'dispopt','hist');

### Example of use of option datatooltip.

First input argument is a structure.

close all
n=100;
v=3;
m0=3;
Y=randn(n,v);
% Contaminated data
Ycont=Y;
Ycont(1:10,:)=5;
[fre]=unibiv(Ycont);
%create an initial subset with the 3 observations with the lowest
%Mahalanobis Distance
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Ycont,bs,'plots',1);
% mmdplot(out);
figure
plo=struct;
plo.clr = 'b';
spmplot(out,'datatooltip',1,'plo',plo);

### First example of the use of options selunit when first input argument is a 2D array.

In this case row names of Y are not specified so numbers in the interval 1:n are added to the scatters.

n=100; p=5;
seluni=[10 30];
Y =randn(n,p);
Y(seluni,:)=Y(seluni,:)+2;
% add labels for units inside vector seluni
spmplot(Y,'selunit',seluni);

### Second example of the use of options selunit when first input argument is a 2D array.

In this case the row names are contained inside input argument plo.label

close all
x1 = Weight;
x2 = Horsepower;    % Contains NaN data
y = MPG;    % response
Y=[x1 x2 y];
% Remove Nans
boo=~isnan(y);
Y=Y(boo,:);
RowLabelsMatrixY=Model(boo,:);
seluni=[10 30];
plo=struct;
plo.label=cellstr(RowLabelsMatrixY);
% add labels for units inside vector seluni
spmplot(Y,'selunit',seluni,'plo',plo);

### Option datatooltip combined with rownames.

Example of use of option datatooltip.

% First input argument is a structure.
close all
x1 = Weight;
x2 = Horsepower;    % Contains NaN data
y = MPG;    % response
Y=[x1 x2 y];
% Remove Nans
boo=~isnan(y);
Y=Y(boo,:);
Model=Model(boo,:);
m0=5;
[fre]=unibiv(Y);
%create an initial subset with the 3 observations with the lowest
%Mahalanobis Distance
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Y,bs,'plots',0);
% field label (rownames) is added to structure out
% In this case datatooltip will display the rowname and not the default
% string row.
out.label=cellstr(Model);
figure
plo=struct;
plo.clr = 'b';
spmplot(out,'datatooltip',1,'plo',plo);
% The units which are already labelled in each panel of the scatter
% plot matrix are those which in the search had a Mahalanobis distance
% greater than 2.5. Note that the labelling is controlled by option selunit.

### Interactive example 2. Example of the use of options selstep and selunit combined with databrush.

%   selunit is passed as a character.
%   It produces a scatter plot matrix in which labels are put for units
%   which have a Mahalanobis distance greater than str2num(selunit). When a set of
%   units is brushed in the spmplot in the monitoring MD
%   plot the labels for the units which have a MD greater than 10
%   are added in steps selsteps.
x1 = Weight;
x2 = Horsepower;    % Contains NaN data
y = MPG;    % response
Y=[x1 x2 y];
% Remove Nans
boo=~isnan(y);
Y=Y(boo,:);
Model=Model(boo,:);
m0=5;
[fre]=unibiv(Y);
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Y,bs,'plots',0);
spmplot(out,'selstep',[60 80],'selunit','10',...
'databrush',{'persist','off','selectionmode' 'Rect'});

### Interactive example 3. Example of the use of options selstep and selunit.

%   selunit is passed as a numeric vector.
%   It produces a scatter plot matrix in which labels are put for units
%   selunit. When a set of
%   units is brushed in the spmplot in the monitoring MD
%   plot the labels for the units selunit
%   are added in steps selsteps.
x1 = Weight;
x2 = Horsepower;    % Contains NaN data
y = MPG;    % response
Y=[x1 x2 y];
% Remove Nans
boo=~isnan(y);
Y=Y(boo,:);
Model=Model(boo,:);
m0=5;
[fre]=unibiv(Y);
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Y,bs,'plots',0);
spmplot(out,'selstep',[60 80],'selunit',1:5,...
'databrush',{'persist','off','selectionmode' 'Rect'});

### Interactive example 4. Example of the use of options selstep and selunit.

%   selunit is passed as a cell array of length 2.
%   It produces a scatter plot matrix in which labels are put for units
%   which have a min MD > selunit{1} and max MD <selunit{2}. When a set of
%   units is brushed in the spmplot in the monitoring MD
%   plot the labels for the units selunit
%   are added in steps selsteps.
x1 = Weight;
x2 = Horsepower;    % Contains NaN data
y = MPG;    % response
Y=[x1 x2 y];
% Remove Nans
boo=~isnan(y);
Y=Y(boo,:);
Model=Model(boo,:);
m0=5;
[fre]=unibiv(Y);
fre=sortrows(fre,4);
bs=fre(1:m0,1);
[out]=FSMeda(Y,bs,'plots',0);
spmplot(out,'selstep',[60 80],'selunit',{'1.2' '1.6'},...
'databrush',{'persist','off','selectionmode' 'Rect'});

## Input Arguments

### Y — data matrix (2D array or table) containing n observations on v variables or a structure 'out' coming from function FSMeda. Matrix or struct.

If Y is a 2D array or table, varargin can be either a sequence of name/value pairs, detailed below, or one of the following explicit assignments:

spmplot(Y,group);

spmplot(Y,group,plo);

spmplot(Y,group,plo,dispopt);

where group, plo and dispopt have the meaning described in the pairs/values section.

If varargin{1} (that is second input element) is a n-elements vector, then it is interpreted as a grouping variable vector 'group'. In this case, it can only be followed by 'plo' and 'dispopt'. Otherwise, the program expects a sequence of name/value pairs.

If first input Y is a structure (generally created by function FSMeda), then this structure must have the following fields:

Value Description
Y

a data matrix of size n-by-v.

If the input structure Y contains just the data matrix, a standard static scatter plot matrix will be created.

On the other hand, if Y also contains information on statistics monitored along a search, then the scatter plots will be linked with other (forward) plots with interaction possibilities, enabled via brushing and datatooltip. More precisely, with option databrush it is possible to create an automatic interaction with the other plots, while with option datatooltip it is possible to retrieve information about a particular unit once selected with the mouse).

Optional fields in input structure Y.

MAL

matrix containing the Mahalanobis distances monitored in each step of the forward search. Every row is associated with a unit (this is a necessary field if the user wants to brush the scatter plot matrix).

Un

matrix containing the order of entry of each unit (necessary if datatooltip is true or databrush is not empty).

label

cell of length n containing the labels of the units.

This optional argument is used in conjuction with options databrush and datatooltip.

When datatooltip=1, if this field is not present labels row1, ..., rown will be automatically created and included in the pop up datatooltip window else the labels contained in Y.label will be used.

When databrush is a cell and it is called together with option 'labeladd' '1', the trajectories in the malfwdplot will be labelled with the labels contained in Y.label.

Data Types: single|double

### Name-Value Pair 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 single quotes (' '). You can specify several name and value pair arguments in any order as  Name1,Value1,...,NameN,ValueN.

Example:  'group',group , 'plo',1 , 'dispopt','box' , 'tag','myspm' , 'overlay',1 , 'undock', [1 1; 1 3; 3 4] , 'selunit','3' , 'datatooltip','' , 'databrush',1 , 'subsize',10:100 , 'selstep',100 

### group —grouping variable.vector with n elements.

group is a grouping variable defined as a categorical variable, numeric, or array of strings, or string matrix, and it must have the same number of rows as Y. This grouping variable that determines the marker and color assigned to each point.

Remark: if 'group' is used to distinguish a set of outliers from a set of good units, the id number for the outliers should be the larger (see optional field 'labeladd' of option 'plo' for details).

Example:  'group',group 

Data Types: char

### plo —names, labels, colors, marker type.empty value, scalar | structure.

This options controls the names which are displayed in the margins of the scatter-plot matrix and the labels of the legend.

If plo is the empty vector [], then nameY and labeladd are both set to the empty string '' (default), and no label and no name is added to the plot.

If plo = 1 the names Y1,..., Yv or the variable names of the table are added to the margins of the the scatter plot matrix else nothing is added.

If plo is a structure, it is possible to control not only the names but also, point labels, colors, symbols. More precisely structure pl may contain the following fields:

Value Description
labeladd

if it is '1', the elements belonging to the max(group) in the spm are labelled with their unit row index or their rowname. The rowname is taken from plo.label or if plo.label is empty from The default value is labeladd = '', i.e. no label is added.

nameY

cell array of strings containing the labels of the variables. As default value, the labels which are added are Y1, ..., Yv.

clr

a string of color specifications. By default, the colors are 'brkmgcy'.

sym

a string or a cell of marker specifications. For example, if sym = 'o+x', the first group will be plotted with a circle, the second with a plus, and the third with a 'x'.

This is obtained with the assignment plo.sym = 'o+x' or equivalently with plo.sym = {'o' '+' 'x'}.

By default the sequence of marker types is:

'+';'o';'*';'x';'s';'d';'^';'v';'>';'<';'p';'h';'.' plo.siz: scalar, a marker size to use for all plots. By default the marker size depends on the number of plots and the size of the figure window. Default is siz = '' (empty value).

plo.doleg: a string to control whether legends are created or not.

Set doleg to 'on' (default) or 'off'.

plo.label : cell of length n containing the labels of the units. If this field is empty the sequence 1:n will be used to label the units.

Example:  'plo',1 

Data Types: Empty value, scalar or structure.

### dispopt —what to put on the diagonal.character.

String which controls how to fill the diagonals in a plot of Y vs Y (main diagonal of the scatter plot matrix). Set dispopt to 'hist' (default) to plot histograms, or 'box' to plot boxplots.

REMARK 1: the style which is used for univariate boxplots is 'traditional' if the number of groups is <=5, else it is 'compact'.

Example:  'dispopt','box' 

Data Types: char

### tag —plot tag.string.

string which identifies the handle of the plot which is about to be created. The default is to use tag 'pl_spm'. Notice that if the program finds a plot which has a tag equal to the one specified by the user, then the output of the new plot overwrites the existing one in the same window else a new window is created.

Example:  'tag','myspm' 

Data Types: char

### overlay —Superimposition on the panels out of the main diagonal of the scatter matrix.scalar, char | structure.

It specifies what to add in the background for the panels specified in undock (default is for all oh them).

The default value is overlay='', i.e. nothing is changed. If overlay=1 the the filled contours are added to each panel, considering all groups, as default. If overlay is a structure it may contain the following fields:

Value Description
type

Type of plot to add in the background or to superimpose. String. It can be: 'contourf', 'contour', 'ellipse' or 'boxplotb', specifying respectively to add filled contour (default when overlay=1), contour, ellipses or a bivariate boxplot (see function boxplotb.m).

include

Boolean vector specifying which groups to include in the type of plot specified in overlay.type, the default value is a vector of ones (i.e. all groups).

cmap

The colormap for the type 'contourf' and 'contour' is grey as default. In these case, this field may specify the colors used for the color map. It is a three-column matrix of values in the range [0,1] where each row is an RGB triplet that defines one color.

Check the colormap function for additional informations.

conflev

When the type specified is 'ellipse', the size of the ellipses is chi2inv(0.95,2) as default. In this case, this field may specify a different confidence level used and it is a value between 0 and 1.

Example:  'overlay',1 

Data Types: single | double

### undock —Panel to undock and visualize separately.matrix | logical matrix.

If undock='' (default), no panel is extracted. If undock is a r-by-2 matrix, it specifies the r coordinates of the scatter plot matrix to undock and visualize separately in a bivariate plot (i.e. for panels out of the main diagonal plots) or in an univariate plot (i.e. the ones on the main diagonal). If undock is a v-by-v logical matrix, where v are the number of columns in Y, the trues of undock are undocked and visualized separately.

REMARK - When used, undock automatically deletes the plots obtained by spmplots. If it is desired to keep some of them, the respective 'Tag' associated has to be changed (e.g.

selecting the figure and then: set(gcf,'Tag','newTag');).

Example:  'undock', [1 1; 1 3; 3 4] 

Data Types: single | double | logical

### selunit —unit labelling in the spmplot and in the malfwdplot.cell array of strings | string | numeric vector for labelling units.

When input argument Y is a structure the threshold is associated with the trajectories of the Mahalanobis distances monitored along the search.

If it is a cell array of strings, only the units that in at least one step of the search had a Mahalanobis distance greater than selunit{1} or smaller than selline{2} will have a textbox in the scatter plot matrix and in the associated malfwdplot after brushing.

If it is a string it specifies the threshold above which labels have to be put. For example selunit='2.6' means that the text labels in the scatter plot matrix (and in the malfwdplot after brushing) are added only for the units which have in at least one step of the search a value of the Mahalanobis distance greater than 2.6.

If it is a numeric vector it contains the list of the units for which it is necessary to put the text labels in each panel of the spmplot and in the associated malfwdplot (if input option databrush is not empty). For example if selunit is [20 34], the labels associated to rows 20 and 34 are added to each scatter plot. The labels which are used are taken from Y.label is Y is a structure or from plo.label if plo.label is notemp and Y is a 2D array, else the numbers 1:n are used.

The default value of selunit is string '2.5' if input argument Y is a structure else it is an empty value if input argument Y is a matrix.

Example:  'selunit','3' 

Data Types: numeric or character

### datatooltip —interactive clicking.empty value (default) | structure.

If datatooltip is not empty the user can use the mouse in order to have information about the unit selected, the step in which the unit enters the search and the associated label. If datatooltip is a structure, it may contain the following fields:

Value Description
DisplayStyle

Determines how the data cursor displays.

SnapToDataVertex

Specifies whether the data cursor snaps to the nearest data value or is located at the actual pointer position. The default options of the structure are DisplayStyle='Window' and SnapToDataVertex='on'.

Example:  'datatooltip','' 

Data Types: empty value, scalar or struct

### databrush —interactive mouse brushing.empty value (default), scalar | cell.

DATABRUSH IS AN EMPTY VALUE.

If databrush is an empty value (default), no brushing is done.

The activation of this option (databrush is a scalar or a cell) enables the user to select a set of observations in the current plot and to see them highlighted in the malfwdplot, i.e. the plot of the trajectories of all observations, grouped according to the selection(s) done by brushing. If the malfwdplot does not exist it is automatically created.

In addition, brushed units can be highlighted in the other following plots (only if they are already open):

- minimum Mahalanobis distance plot;

Remark. the window style of the other figures is set equal to that which contains the spmplot. In other words, if the scatterplot matrix plot is docked all the other figures will be docked too.

DATABRUSH IS A SCALAR.

If databrush is a scalar the default selection tool is a rectangular brush and it is possible to brush only once (that is persist='').

DATABRUSH IS A CELL.

If databrush is a cell, it is possible to use all optional arguments of function selectdataFS and the following optional argument:

- persist = Persistent brushing.

Persist is an empty value or a scalar containing the strings 'on' or 'off'.

The default value of persist is '', that is brushing is allowed only once.

If persist is 'on' or 'off' brushing can be done as many time as the user requires.

If persist='on' then the unit(s) currently brushed are added to those previously brushed. It is possible, every time a new brushing is done, to use a different color for the brushed units.

If persist='off' every time a new brush is performed units previously brushed are removed.

- labeladd= point labelling. If this option is '1', we label the units of the last selected group with the unit row index in input Y if Y is a matrix or with the labels contained in Y.label if input Y is a struct.

The default value is labeladd='', i.e. no label is added in the malfwdplot.

Remark: The options which follow (subsize, selstep and selunit) work in connection with previous option databrush and produce their effect on the monitoring MD plot (malfwdplot). Note that the options which follow can only be used if the first argument of spmplot is a structure containing information about the fwd search (i.e. the fields MAL, Un and eventually label).

Example:  'databrush',1 

Data Types: single | double | struct

### subsize —x axis control in malfwdplot.vector.

numeric vector containing the subset size with length equal to the number of columns of matrix Y.MAL.

If it is not specified it will be set equal to size(Y.MAL,1)-size(Y.MAL,2)+1:size(Y.MAL,1)

Example:  'subsize',10:100 

Data Types: single | double

### selstep —position of text labels of brushed units in malfwdplot.vector.

Numeric vector which specifies for which steps of the forward search text labels are added in the monitoring MD plot after a brushing action in the spmplot. The default is to write the labels at the initial and final step. The default is selstep=[m0 n] where m0 and n are respectively the first and final step of the search.

Example:  'selstep',100 

Data Types: single | double

## Output Arguments

### H —array of handles H to the plotted points. 3D array

See gplotmatrix for further details.

### AX —handles to the individual subaxes.  Matrix

See gplotmatrix for further details.

### BigAx —handle to big (invisible) axes framing the subaxes. Scalar

See gplotmatrix for further details.