Displays the distribution of groups in a plane using a trellis of bar or pie charts (R.W. Payne).

### Options

COLOURS = variate or text

`PLOT` = string tokens |
What to plot (`barchart` , `piechart` , `scaledpiechart` , `key` ); default `barc` , `key` |

`NPARTITIONS` = scalar |
Number of partitions along each axis; default 8 |

`COLOURS` = variate or text |
Colours for the groups; default uses the colours defined for pens 2 upwards |

`EQUALAXES` = string tokens |
What aspect of the x- and y-axes to make equal (`bounds` , `scaling` ); default `*` i.e. none |

`KEYHEIGHT` = scalar |
Height of the key; default 0.1 |

`LABELSIZE` = scalar |
Size of labels showing the number of points in each unscaled pie chart; default 1 |

`%MARGINSIZE` = scalar |
Ratio as a percentage for margin sizes to their default sizes in pie charts; default 100 |

### Parameters

`Y` = variates |
Y-coordinates of the points in each graph |

`X` = variates |
X-coordinates of the points in each graph |

`GROUPS` = factors |
Groupings for the points in each graph |

`TITLE` = texts |
Title for each graph |

### Description

`D2GROUPS`

is useful when you have large numbers of points that are classified into groups. The x- and y-coordinates of the points are supplied by the `X`

and `Y`

parameters, and their groups are specified by the `GROUPS`

parameter. `D2GROUPS`

divides the plane into a trellis of squares, and calculates the replications of the groups within each of the squares. The `PLOT`

option specifies how the replications are plotted, with settings:

`barchart`

plots a trellis with a bar chart in each square,

`piechart`

plots a trellis with a pie chart in each square, with a label on the left at the top showing the number of points in the square,

`scaledpiechart`

plots a trellis with a pie chart in each square, each one scaled according to the number of points in the square, and

`key`

includes a key showing the colour used for each group. The default is to plot a bar chart with a key.

The `NPARTITIONS`

option specifies the number of partitions (i.e. the number of tellis boxes) along each axis; default 8. The `COLOURS`

option can specify either a variate or a text to define the colours to be used for the groups. (See `PEN`

for details.) The default is to use the colours defined for pens 2 upwards. The `EQUALAXES`

option allows you to specify that the x- and y-axes should share equal bounds or have equal scaling. By default, they will have their own bounds and scaling, The `KEYHEIGHT`

option specifies the height of the key. This must not be less than 0.1 or greater than 0.5. The default is 0.1. The `LABELSIZE`

option specifies the size of the labels showing the number of points in each unscaled pie chart; default 1. The `%MARGINSIZE`

option specifies the ratio (as a percentage) of the margin sizes in pie charts to their default sizes; default 100. The `TITLE`

parameter can supply a title for the plots; by default there is none. Options: `PLOT`

, `NPARTITIONS`

, `COLOURS`

, `KEYHEIGHT`

, `LABELSIZE`

, `%MARGINSIZE`

. Parameters: `Y`

, `X`

, `GROUPS`

, `TITLE`

.

### Action with `RESTRICT`

If either `X`

, `Y`

or `GROUPS`

is restricted, only the units not excluded by the restriction will be plotted.

### See also

Directives `BARCHART`

, `DPIE`

.

Procedures: `CVATRELLIS`

, `DMSCATTER`

, `DSCATTER`

, `TRELLIS`

.

Commands for: Graphics.

### Example

CAPTION 'D2GROUPS example'; STYLE=meta SPLOAD '%data%/Iris.gsh' D2GROUPS Y=Petal_Length; X=Petal_Width; GROUPS=Species & [PLOT=barchart,piechart,key] Y=Sepal_Length; X=Sepal_Width; GROUPS=Species