5.1.9 Frequency analysis of points - LUPMISManual

5.1.9 Frequency Analysis of Points

Level of expertise required for this Chapter: Advanced; general GIS training. This Chapter is available in improved version in Chapter 5.6.2; it will be deprecated here.

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

1. Preparation:

You might have to prepare your attribute source, if crosstab data are not in the label field in the DRA file):

1a. Copy source DRA file to temp DRA file
1b. 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

2. Inherit:

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 1) > Open > Tick: Inherit label > OK >

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

3. 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 ('Export tabular GIS data').

4. Final frequency distribution in Excel:

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