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 try out the following tools to produce step by step instructions.


Dominant value of an attribute


Enter the following information


Percentage Distribution of a given value of an attribute


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Source: Peter Schut
Contact: Head, CanSIS