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How to map Component Table attributes

These instructions explain how to prepare data stored in the CLI Component Table for mapping.

It is not appropriate to map the primary component in each polygon, since this component will not necessarily share the dominant attribute of the polygon. Choropleth mapping of the primary component will produce deceptive results! The following table is used to illustrate this point.

Table 1:
Sample data from the Component Table
CLI	Component (CMP)	Percent Occurrence	CLASS	Subclass 1
1	1	40	3	C
	2	30	1	P
	3	30	1	W
2	1	75	2
2	2	25	1	T

If the first component is used to map CLI polygon "1", it would be 40% class "3" whereas class "1" covers a larger percentage (60%) of CLI polygon "1". To correctly map data in the Component Table, the percent occurrence field must be summarized by the values of the relevant field, as shown in Table 2.

Table 2:
Sample data summarized by CLASS
CLI	Percent Occurrence	CLASS
1	60	1
1	40	3
2	75	2
2	25	1

There are three ways in which this data can be mapped:

The dominant value (where the Class field is mapped)

Table 3: Dominant Class Value
CLI Percent Occurrence CLASS

1 60 1

2 75 2

2. The percentage distribution of a value (where the Percent Occurrence field is mapped)

**Table 4: Percent Distribution of Class "1"**
CLI	Percent Occurrence	Percent Distribution CLASS
1	60	1
2	25	1

3. Queries of the Component Table (ie All Class 1 that are also subclass P are higlighted in yellow)

**Table 5: Query of the Component Table**
CLI	Percent Occurrence	CLASS	SUBCLASS
1	60	1	P
1	40	3	W
2	75	2	S
2	25	1	P

You can use the Component Table Mapping Extension for ARCVIEW to facilitate this mapping process, or try out the following tools to produce step by step instructions.

Source: Peter Schut
Contact: Head, CanSIS