The Geostat plugin allows advanced cartographic representation based on attributes of geospatial data. Currently, there is only support for polygonal entities. There will be support for ponctual symbol very soon. Every vectorial formats supported by Mapserver may be use.
The client side of the plugin allow the specification of the mandatory and optional paramaters. These parameters will be passed to the server side which will create the map layer and return some informations about the dataset.
On the server side, the first configuration step is made within the mapfile.
The only requirement is a least on polygonal layer which expose at least one
attribute. You may consider an attribute as exposed if you can use it as
CLASSITEM for this layer. You must add one (and only one) class to this
layer. It will be use as template for the generated classes. You may use
this class to define border color, label or other default parameter.
You should not add this layer to the layers.ini
configuration file.
Choropleth layers are managed differently then ordinary layer within
cartoweb. server_conf/mapId/geostat.ini is used to
define layers that may be used for geostatistics. Take a look to a sample
of this file.
geostat.0.mslayer = region_geostat_fill
geostat.0.label = Region
geostat.0.choropleth = true
geostat.0.choropleth_attribs = POPULATION,HOUSINCOME
geostat.0.choropleth_attribs_label = "Population","Average house income"
These example represents a single layer definition. The general for of
parameter is geostat.n.key =
value. n is an incremental
number (first layer of the config file is 0. key is
a parameter for this layer. value is the value
associated to the following parameter. The following parameters defined
choropleth generation :
msLayer: name of the layer in the mapfilelabel: Label for the layer in the interfacechoropleth: Should choropleth be activated. This is present for future developmentchoropleth_attribs: Comma separated list of attributes that may be used for choroplethchoropleth_attribs_label: Comma separated list of labels to display as description of the preceding attributes
Client-side configuration allow to specify which algorithms should be display within the user interface. Currently, there are 2 algoriths families that may be configured. The first is about classification algorithms. The second is about generation of color ramp. The signification of the parameter is pretty straightforward.
The choroplethDataFromCurrentBoundingBox parameter
allows to choose whether classes should change when users zoom or if they
should remain constant for every scales.
;The following classification method are currently supported
; Custom : 0
; Equal intervals : 1
; Quantils : 2
; Modes : 3
choroplethClassifMethodDefault = 2
choroplethClassifMethodsList = 0,2,3
;The following color ramp generation method are currently supported
; Custom : 0
; RGB interpolation : 1
; HSV interpolation : 2
; Max diffrence : 3
choroplethColorRampMethodDefault = 1
choroplethColorRampMethodList = 1,3
choroplethDataFromCurrentBoundingBox = false
