ClassifyLogInterval

Classify functions ClassifyLogInterval

syntax

Since GeoDMS 20.20.0 the second form classifies a value-count table that was calculated before, with values and count the two [[subitem sub items]] of a weeded_counts result. Use it when more than one result is derived from the same scan of a, since the [[calculation cache]] then calculates that scan once; the GeoDMS GUI uses it for the classification it generates for a map layer without a configured Classification. Below 4096 distinct values it gives the same class breaks as the two argument form; above it they can differ, because weeded_counts merges values that the two argument form counts separately.

definition

ClassifyLogInterval(a, domain unit) results in a Data item with class breaks, based on a logarithmic interval distribution of classes. The resulting Values unit is the values unit of data item a, the resulting domain unit is the domain unit Argument.

  • a: numeric data item to be classified
  • domain unit: determining the number of class breaks.

description

A logarithmic interval of classes means the data item to be classified is split up in classes with, as far as possible, an equal logarithmic interval size of each class.

The same function can also be applied from the GUI, by requesting the Palette Editor of a map layer and activating the Classify > Logarithmic Intervals classification.

The ClassifyLogInterval results in a set of ClassBreaks that can be used in the Classify function to classify a data item.

applies to

  • data item a with Numeric Value type
  • domain unit with value type from group CanBeDomainUnit

since version

7.019

example 

attribute<nrPersons> classifyLiNrInh (inh_4K) := ClassifyLogInterval(NrInh, inh_4K);
classifyLiNrInh
0
1
10
100

Table inh_4K, nr of rows = 4

NrInh
550
1025
300
200
0
null
300
2
20
55
860
1025
1025
100
750

Table District, nr of rows = 15