Categorised classification

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Categorized classification in QGIS groups spatial data into distinct categories based on specific attributes. This classification enhances the organization and interpretation of geospatial information for clearer insights.

Categorized classification is usually used for nominal and ordinal scaled data.

Data Scale	Definition	Example	Typical Data Format
Nominal Scale	Categories without inherent order or ranking	Land cover types, districts, livelihood zones	Text (“Desert”) or Integer (5)
Ordinal Scale	Categories with a meaningful order or ranking	Ranks (e.g., low, medium)	Text (“high”) or Integer (5)

Video: Classifying Data

To classify data in categories…

• Right-click on your layer

• Click on Symbology

• Click on Categorized

• In the Value dropdown menu select the column based on which you want to categorize your data.

• Further down the window click on Classify. Now you should see all unique values or attributes of the selected column in Value. To add or delete single values use the - and + buttons.

• Optional: In the Symbol dropdown menu you can select the colours and symbols you want to use

• Optional: In the Color ramp dropdown menu you can specify the range of colours you want to use

• Optional: You can open the panel Layer Rendering on the button of the window. Here you can adjust the opacity/ transparency of the layer.

• Click Apply to put your adjustment into effect.

• Click OK to close the window.