Section Four: Advanced Features

Part Two: Further Analysis

This section of the tutorial demonstrates features of MapInfo which users may require in future. If you do not have the files discussed in these examples then you do not need to use the feature! However, all of these are useful for future reference when additional data may have been obtained.

Creating points

Points may be added to maps which have already been created, for example, if you had a .tab file such as ward boundaries for Bradford, and a point coverage, perhaps imported from ArcGIS, of all the high schools in Bradford with x and y co-ordinates. Open the two relevant files.
Go to Table > Create Points. A dialog box appears. From 'Create points from table,' choose the table containing the points from the drop down list. Choose the columns in that table which contain the X and Y co-ordinates for the points you wish to create, and choose an appropriate symbol to represent the points.
It is important to set the projection of the co-ordinates for the new points. To find out the projection of the existing map, make sure it is the active window, then go to Table > Maintenance > Table Structure. Click the Projection button. Match the projection of the co-ordinates of the points to this.
Click OK when you are happy with your options. Then go to Window > New Map Window (or use the New Mapper button on the toolbar) to view the points overlaid on the boundary map.

Geocoding

Geocoding means adding geographical data to tables of data without co-ordinates, such as addresses, so that they can be dsiplayed on a map. This is related to adding columns of data to mappable tables, as discussed in Section Two, Part Three.
Geocoding may be done by address, by boundary, or by postcode. Two tables are required - the table of addresses (the geocode table) and the search table, for example, a table showing the National Grid co-ordinate of the centroid of each postcode unit.
Go to Table > Geocode. A dialog box appears. Choose the Geocode table and search table from the drop down lists, and choose the appropriate columns where the X and Y co-ordinates of the points are stored. Then choose between automatic and interactive mode.
Automatic mode requires no further input on the point of the user, but will not geocode points for which there is not an exact match. Interactive allows the user to choose the nearest alternative when there is not an exact match (e.g. to assign the point to te adjacent postcode unit). Click OK to begin geocoding.
The results may be displayed as a map layer.
If you cannot see the results of your geocoding operation the layer containing the results is probably not the top layer. Go to Map > Layer Control and change the order of the map layers to rectify this.

Redistricting

Redistricting allows spatial units to be combined int larger spatial units based on their common characteristics. For example, enumeration districts may be combined into wards. MapInfo also sums the data for the newly comined units, and provides totals of these data. There are two methods to do this.
The first method is non-systematic, with the choice of spatial units to be combined entirely subjective. This uses the same process as discussed in Section Two, Part Three, where a new field is added to the existing table to receive the summed data, the spatial units to be combined (which must be adjacent) are selected, and the column is updated (using Table > Update Column.
However, the usual way to perform a redistricting operation is to use Window > New Resdistrict Window (or to use the New Redistricter icon on the toolbar). A dialog box appears.
Choose the table you wish to work with from the drop down list. Choose the field containing the spatial units you wish to combine. Choose which of the Available Fields on the left you wish to know the value of for the new spatial unit and transfer these over to the right using the Add >> button. Use the shift key to select all the fields. Use the << Remove button to move fields from the right back over to the left if you do not wish to include them. Do not remove the field representing the spatial unit though, for example, zone ID. Click OK.
The results of the Redistrict operation appear on the map and in a new browser window entitled District. In the browser, click on in the symbol field to change the symbol for that record.
To make the new districts permanent and save them to the table, go to Redistrict > Assign Selected Objects.
If you do not wish to overwrite your original table with your new one, save a copy of your work before beginning, and give the new table another title.

Buffering

Buffers are used to show distances from objects. Firstly, make sure the layer containing the objects you wish to buffer is selectable using the Layer Contol dialog box (Section Three, Part One). Then select the object(s) you wish to buffer using the methods discussed in Section Four, Part One.
Go to Options > Buffer. A dialog box appears allowing the user to select the distance they would like to buffer, and whether they would like one buffer around all the selected objects or one around each. Click OK when you are happy.
If you cannot see the results of your buffering operation the layer containing the results is probably not the top layer. Go to Map > Layer Control and change the order of the map layers to rectify this.

Drawing and editing

You may wish to add your own drawing objects to a map. Firstly make sure the map layer you wish to work with is editable using the Layer Control dialog box (Section Three, Part One).
Use the tools on the drawing toolbar (Section One, Part Two) to add objects to the map.
To save your changes go to Map > Save Cosmetic Objects. Give the table a new name so that you do not overwrite your previous work.

On to Section Four, Part Three: MapBasic

Section Four
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