How to group zones in GeoAgro GIS
In a Productivity map, polygons are divided in 7 different classes: VERY HIGH, HIGH, MEDIUM TO HIGH, MEDIUM, MEDIUM TO LOW, LOW AND VERY LOW. The management zones map will group those polygons in 3 different classes: LOW, MEDIUM and HIGH.
- Carry out a search based on the “Management zone” criteria to choose all items characterized as, let's say, MEDIUM. This will include MEDIUM TO HIGH, MEDIUM and MEDIUM TO LOW. To do this, use the Find_Objects tool in the Navigation panel:
- A dialog will pop up asking you to enter your search criteria. E.g.
- Layer: Management zones
- Field: Management zone
- Wording: ==(contains)
- Valor: 'MEDIUM".
- Click on Accept to do your search.
- GeoAgro GIS will now select all items containing the aforementioned 3 values.
Modifying data in the selected polygons
In order to identify the selected polygons as part of the same management zone, you need to enter the same value for all of them in the corresponding structure column
- Having your items selected, click on the Edit selected object data tool from the Edition panel.
- A table will pop up showing rows corresponding to each selected object, and columns corresponding to each atrribute. Clicking on a cell will show a cursor, allowing you to modify existing data or add new.
|Note:||You may modify data only from those columns colored yellow. White columns are completed automatically and cannot be modified.|
- Enter the "MEDIUM" value in the Management zone attribute for all selected objects. You may do it cell by cell or modify all data at once by double clicking in any cell. A new dialog will pop up, asking you to enter the value you want to assign to the whole column. Click on Accept.
- You have now automatically assigned the MEDIUM value to all cells in the column. To finish this, click on the Save button.
All your polygons are now identified under a single management zone. However, they're still separate objects. You now need to join them and merge them into a single polygon.
- Click on the Edit Object button in the Edition panel. The Drawing tools panel will show up. Click on the Join objects tool.
- A window will pop up, asking you to choose the main object; its data will be kept and assigned to the new object which will absorb all other polygons. In this case, all objects have similar values, so you may pick the first item and click on Accept.
- The split between polygons will disappear. As a consequence, all objects which used to have the word "MEDIUM" among its attributes have now merged into a single object named "MEDIUM".
You may now do the same process to generate your other two management zones, LOW and HIGH.
To finish the process, you may now assign a symbology which will allow you to identify each polygon with a different colour.
- Make sure the Management zones layer is active.
- Click the Edit cartography and layer properties tool in the Edition panel.
- A dialog will pop pup. Select the Symbology Tab and the option Classes.
- Use the Classes wizard to generate your classes. In Identifier select the attribute you'd like to use to differentiate objects; in this case, Management Zones. Click on "Accept" and you will now have three classes based on those values: HIGH, MEDIUM and LOW.
- For each layer, assign these colors:
- LOW: Yellow
- HIGH: Blue
- MEDIUM: Green