How to map Component Table attributes

These instructions explain how to prepare data stored in the SLC 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

Polygon (SL)	Component (CMP)	Percent Occurrence	Soil Development (DEVEL)	...other attributes
1	1	40	Brown Solonetzic
	2	30	Brown Chernozemic
	3	30	Brown Chernozemic
2	1	75	Regosolic
	2	25	Brown Chernozemic

If the first (highest percentage) component is used to map soil development, "Brown Solonetzic" will be shown in polygon 1, whereas "Brown Chernozemic" covers a larger percentage of the polygon.

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 DEVEL

Polygon (SL)	Percent Occurrence	Soil Development (DEVEL)
1	60	Brown Chernozemic
1	40	Brown Solonetzic
2	75	Regosolic
2	25	Brown Chernozemic

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

1. The dominant value (where the Soil Development field is mapped)

   Dominant soil development

   Polygon (SL)	Percent Occurrence	Soil Development (DEVEL)
   1	60	Brown Chernozemic
   2	75	Regosolic

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

   % distribution of "Brown Chernozemic"

   Polygon (SL)	Percent Occurrence	Soil Development (DEVEL)
   1	60	Brown Chernozemic
   2	25	Brown Chernozemic

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.

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Dominant value of an attribute

Enter the following information

SLC coverage name (UPPERCASE)
Item to be mapped	KINDMAT VEGET PMDEP CFRAG ROOTDP DRAIN DEVEL CALC LOCSF SLOPE
GIS system	ARC/INFO ARCVIEW

and then press: .

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Percentage Distribution of a given value of an attribute

Enter the following information

SLC coverage name (UPPERCASE)
Item to be mapped	KINDMAT VEGET PMDEP CFRAG ROOTDP DRAIN DEVEL CALC LOCSF SLOPE
Value of item to be mapped
GIS system	ARC/INFO ARCVIEW

and then press: .

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Source: Peter Schut
Contact: Head, CanSIS