5.6.2 Points per polygons - LUPMISManual

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5. Conversion of data > 5.6 Export to tables

5.6.2 Points Over Polygons: Frequency Analysis of Points

Level of expertise required for this Chapter: Advanced; general GIS training. This Chapter is repeated in 5.1.9 (shortly to be deprecated).

For a GIS crosstabulation to produce statistics how many points occur in particular areas, you overlay points with polygons (also called 'point crosstabulation').

1. Preparation of point map

You have to p
repare your point map:

- Copy point DRA file to temp DRA file

2. Preparation of polygon map

You have to prepare your polygon overlay map:

2a. Copy polygon DRA file to temp DRA file
2b. If the overlay information is in the ID field: Copy this temp DRA file to live layer, then
Live layer actions > IDs and labels > Amend labels and IDs > OK > Set display labels equal to IDs > OK > Save live layer as... > Same name > Save

3. Inherit

You can now transfer the information of the polygon map to the point map with the Inherit command:

Utilities > Vector utilities > Actions > Choose DRA file of points > Open > Transform window: Spatial queries > Inherit attributes from other file > OK >

Inherit attributes from other file window: Polygons file > Select temp DRA file (from step 2) > Open > Tick: Inherit label > OK >

Save as window: Specify new file name (DRA file)

4. Export crosstabulation for all points

Utilities > Database utilities > Generate database from DRA > Select file, just created > Open > Generate database window:
Tick Display label > OK > Save as window: Specify new file name > Save as type: CSV > Save.

This step is also explained in Chapter 5.6.1 ('Export tabular GIS data: From DRA').

5. Final frequency distribution in Excel

The next steps are carried out in Excel, explained in Annex 20.2 (Excel: Frequency).


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