Rummaging in the Toolbox – Connect the Dots with the Spider Graph tool
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The Spider Graph tool creates lines between objects in a single table, or between objects from two tables based on a common identifier, for example, let' say you have stores and customers. If both tables have a store identifier then the Spider Graph tool can be used to create lines connecting each customer to their store.
The resulting table contains the lines as well as chosen attributes from the input table(s), together with a column that stores the length of each line. The lines can be color-coded based on their attribute of origin.
How does it work?
The first step is to load the Spider Graph tool using the Tool Manager. In the 32 bit versions of MapInfo Pro this is in the Tools menu (click on the Tool Manager command)
In the 64 bit version the Tool Manager is found on the Home tab. You can also open it up into a separate window from the Window Gallery (also on the Home tab).
Next, you access the Spider Graph dialog box as follows:
The Spider Graph dialog box appears below.
Figure 1: The map now includes the new table containing the lines. This can be used as the end result for printing or exporting, or as starting point for further analysis.
Did you know?
In some analytic models the lengths of the resulting lines in a Spider Graph are used as an approximate rating for driving time and accessibility. It is interesting that for various countries or in different areas, different weighting factors can be applied to the line lengths in relation to the density of the local road network and traffic congestion.
It is also possible to use the resulting line lengths to represent the 'willingness to travel' in a customer profile. Just as in regular drive time analysis you will find a decay effect when aggregating line lengths in classes. See the next screen shot below for an example:
If approximating driving time and accessibility in this way is considered to be insufficient, consider using Pitney Bowes Software's desktop or service based Drivetime solutions.
Figure 2: Decay effect for length with percentages. It is intuitive to consider that fewer people will travel longer distances to visit a store or service location. This analysis can help quantify the changes as distance increases in more detail.
Why is it useful?
The Spider Graph tool provides visual and analytic insight in your data:
- about connections between customers and stores they visit
- warehouses and amount and volume of deliveries
- mobile phones connecting to telecom antennas
- crimes scenes to crook hideouts
- assigned post code areas as part of sales zones to branch offices etc
- visualize where students are going to school or patients are going to hospitals
Figure 3: Visualizing assigned post code areas for a branch office
By using different thematic displays you can even bring more information to the map. For example, you can colorize all lines connecting to a specific end point, apply line width based on the length or any other attribute you connect to the line to display the weight of each line.
Figure 4: Detail of Spider Graph map displaying delivered volumes.
Original article written by Emil Zegers, Pre-sales Engineer.