Creating Thematic Maps in MapInfo _ Geo Information

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18.6.2014 Creating Thematic Maps in MapInfo | Geo Information

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Thematic Maps use a theme to visualise the data stored in a table. Themes represent data with shades

of colour; fill patterns, symbols, grids or charts. They have several advantages:

1. They can be used to visualise complex statistical data,

2. They are quicker to apply than splitting a table and changing the style of each part manually3. They dont disrupt the table

Planning a thematic map

It is important to understand the elements that comprise a thematic map.

4. Thematic Variables This is the data to be displayed (e.g. housing numbers, soil type)

5. Thematic Types:

6. Ranges Data is grouped into ranges (e.g. population


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From the menu, select Map, Create Thematic Map

In the dialogue box, select Individual on the left bar, and Region Indv Value from the list inside the box

Now select the source table and field. In this case the table is Minerals and the field is Description.

Press next. The styles and legend box appears:
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Select the desired style for each individual value.

When complete, press Ok. Now Press the Legend button to edit how each item will appear in the legend:

Items that dont need to be shown in the legend can be hidden by unticking the Show This Range box.

This is useful when one style has been applied to several different items. Eg. If Chalk, Sand and Clay are

being grouped together as Soft Rock., the same style should be applied to all three. However, having

three separate Soft Rock entries in the legend would look very untidy. Therefore, the Show this Range

box should be ticked for one Soft Rock entry but unticked for the remaining two.

Press Ok to close the customize legend box, and press ok to close the Create Thematic Map dialogue


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box.

The new thematic will now appear in the Map Window. The thematic is controlled via a new entry in the

layers panel.

Range based region Style

The following example uses the amount of retail floor space per parish in Wokingham.

1. A query is needed to update the Parish boundary table (clear polygon with red lines) with the amount

of retail floor space which is detailed in the table LandUse_Classes (the small black polygons shown

within each parish).


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12. A query is needed to update the Parish boundary table with the retail floor space. MapInfo can

update columns based on calculations of data in other tables.

13. Select Table, Update Column. The table to update is Parish Boundaries; the column to update is

Retail_sq_m.

14. Select Land Use Classes in the get value from box. The join between the two tables will need to be

specified, as the update is based on data from the other table.

15. Press the join button. In this case the join is where the object from Land Use classes is within the

Parish boundaries. The other spatial option is where an object contains the other one. You can also

join based on data attributes, for example where the County column of a shops address matched

the name column of a table of county boundaries.

You can see how the column has updated:-
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Applying the thematic

Select Map, create Thematic Map

In the dialogue box, select Region Ranges Solid Fill

In the next box (Step 2 of 3) select the table and field the thematic will be based on.


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Step 3 of 3 gives the options to customise the thematic:

Press Ranges to customise the ranges that each colour shade will represent:

Press Styles to customise the style for each range.

Clicking the box in the lower right corner of the colour grid allows custom colours to be entered by their

RGB or Hue, Saturation values:

Back on the Modify thematic map dialogue box, press the Legend button to enter the Customise Legend

text box.
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When satisfied with the thematic map, press ok on all open dialogue boxes to close them. The thematic

will be displayed:-

It is possible to save Thematic Templates. In the Modify Thematic Map dialogue box, press the Template

Save As button. The template file is saved as a .thm file in the Documents and Settings\username?

\Application Data\MapInfo\Professional\version?\ ThmTmplt. To re-use a template, press the merge

button in the Modify Thematic Map dialogue box.

Labels

I would like to label each parish with its name and the amount of retail floorpace.


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Right click on the Parish Boundaries layer, and select Layer Properties

Select the Label Display tab.

Select Label With pull down and select expression, as we are combing two columns plus some

formatting commands.

In the expression box, enter the following: Feature_Name+Chr$(13)+Format$(Retail_sq_m, 0.00)

Select the font, label position and press ok.

Click the label tag on the far right of the Parish Boundaries in the Layer Control panel

Lets examine the labelling expression: Feature_Name+Chr$(13)+Format$(Retail_sq_m, 0.00)

Feature_Name is the first column to be used for the label

Char$(13). Char$() enters a special character. Char$(13) enters a line break

Format$(Retail_sq_m, 0.00) Format$() formats the label string that is enclosed in its brackets. In

this case Format$(Retail_sq_m, 0.00) adds the Retail_sq_m column but formats it to 2 decimal

places.

To achieve this label without an expression, I would have needed to have 2 copies of the parish

boundary table (one to be labelled with the name, another to be labelled with the retail floor space. Plus,

I would have needed to have added an extra column with the retail floor space formatted to decimal

places.
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Creating Thematic Maps in MapInfo _ Geo Information

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