Matrix of scatter plots by group

`gplotmatrix(x,[],group)`

`gplotmatrix(x,y,group)`

`gplotmatrix(x,y,group,clr,sym,siz)`

`gplotmatrix(x,y,group,clr,sym,siz,doleg)`

`gplotmatrix(x,[],group,clr,sym,siz,doleg,dispopt)`

`gplotmatrix(x,[],group,clr,sym,siz,doleg,'variable',xnam)`

`gplotmatrix(x,y,group,clr,sym,siz,doleg,[],xnam,ynam)`

`[h,ax,bigax] = gplotmatrix(___)`

`gplotmatrix(x,[],group)`

creates a matrix of scatter plots of
the data in `x`

, grouped by the grouping variable in
`group`

. Each individual set of axes in the resulting figure
contains a scatter plot of a column of `x`

against another column
of `x`

. It also plots the outlines of the grouped histograms in the
diagonals.

`gplotmatrix(x,y,group)`

creates a matrix
of scatter plots. Each individual set of axes in the resulting figure contains a
scatter plot of a column of `x`

against a column of
`y`

. All plots are grouped by the grouping variable
`group`

.

`x`

and `y`

are matrices with the same number of
rows. If `x`

has *p* columns and
`y`

has *q* columns, the figure contains a
*p*-by-*q* matrix of scatter plots. If you
omit `y`

or specify it as the empty matrix, `[]`

,
`gplotmatrix`

creates a square matrix of scatter plots of
columns of `x`

against each other.

`group`

is a grouping variable that can be a categorical
variable, vector, character array, string array, or cell array of character vectors.
`group`

must have the same number of rows as
`x`

and `y`

. Points with the same value of
`group`

are placed in the same group, and appear on the graph
with the same marker and color. Alternatively, `group`

can be a
cell array containing several grouping variables (such as ```
{g1 g2
g3}
```

); in that case, observations are in the same group if they have
common values of all grouping variables.

`gplotmatrix(x,y,group,clr,sym,siz)`

specifies the color, marker type, and size for each group.
* clr* is a character array or string array of colors
recognized by the

`plot`

function.
`sym`

`plot`

command, with the default value
`'.'`

. `siz`

is a vector of sizes, with the
default value determined based on the number of observations. If you do not specify
enough values for all groups, `gplotmatrix`

cycles through the
specified values as needed.`gplotmatrix(x,y,group,clr,sym,siz,doleg)`

controls whether a
legend is displayed on the graph
(* doleg* is

`'on'`

, the
default) or not
(`doleg`

`'off'`

).`gplotmatrix(x,[],group,clr,sym,siz,doleg,dispopt)`

controls what appears along the diagonal of a plot matrix of `x`

.
Allowable values are `'none'`

, to leave the diagonals blank,
`'hist'`

, to plot histograms, `'stairs'`

to
display the outlines of grouped histograms (default if there is more than one
group), `'grpbars'`

to plot grouped histogram bars.

`gplotmatrix(x,[],group,clr,sym,siz,doleg,'variable',xnam)`

displays the variable names along the diagonal of the plot matrix of
`x`

. It also uses these column names to label the
*x-* and *y*-axes.

`gplotmatrix(x,y,group,clr,sym,siz,doleg,[],xnam,ynam)`

labels
the *x-* and *y*-axes using the column names
specified in `xnam`

and `ynam`

.

`xnam`

and `ynam`

must be character arrays,
string arrays, or cell arrays of character vectors, with one name for each column of
`x`

and `y`

, respectively.

`[h,ax,bigax] = gplotmatrix(___)`

returns three arrays of handles for any of the previous input arguments.
`h`

is an array of handles to the lines on the graphs. The
array's third dimension corresponds to groups in the input argument
`group`

. `ax`

is a matrix of handles to the
axes of the individual plots. If

is
`dispopt`

`'hist'`

, `'stairs'`

, or
`'grpbars'`

, `ax`

contains one extra row of
handles to invisible axes in which the histograms are plotted.
`bigax`

is a handle to big (invisible) axes framing the entire
plot matrix. `bigax`

is fixed to point to the current axes, so a
subsequent `title`

, `xlabel`

, or
`ylabel`

command will produce labels that are centered with
respect to the entire plot matrix.