{"id":14527,"date":"2025-07-15T10:00:00","date_gmt":"2025-07-15T08:00:00","guid":{"rendered":"https:\/\/www.sigterritoires.fr\/?p=14527"},"modified":"2025-07-01T10:28:58","modified_gmt":"2025-07-01T08:28:58","slug":"building-an-interactive-dashboard-in-qgis-dynamic-analysis-with-data-plotly-widgets-and-expressions","status":"publish","type":"post","link":"https:\/\/www.sigterritoires.fr\/index.php\/en\/building-an-interactive-dashboard-in-qgis-dynamic-analysis-with-data-plotly-widgets-and-expressions\/","title":{"rendered":"Building an interactive dashboard in QGIS: dynamic analysis with Data Plotly, widgets and expressions"},"content":{"rendered":"\n

<\/span>Objective<\/span><\/h2>\n\n\n\n

Create a dynamic monitoring interface in QGIS with :<\/p>\n\n\n\n

A map that adapts to filtered data<\/li>\n<\/ul>\n\n\n\n

All without leaving the QGIS interface!<\/p>\n\n\n\n

\n\n\n

Contenu <\/p>\nToggle<\/span>

Objective<\/a><\/li>

Use case: monitoring beach litter<\/a>

Step 3: Display dynamic indicators with labels<\/a>

To be continued\u2026<\/a><\/li><\/ul><\/nav><\/div>\n\n\n\n\n

\n\n\n\n

<\/span>Use case: monitoring beach litter<\/span><\/h2>\n\n\n\n

Let’s take our releves_dechets layer with :<\/p>\n\n\n\n

Field Description beach Name of beach type_waste Waste category quantity Quantity observed date_obs Date of observation<\/p>\n\n\n\n

Field <\/th> Description<\/th><\/tr><\/thead>

beach <\/td> Name of beach<\/td><\/tr>

type_waste<\/td> Waste category<\/td><\/tr>

quantity<\/td> Quantity observed<\/td><\/tr>

date_obs<\/td>

Date of observation<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Objective: enable a user to filter data (by range, date\u2026) and immediately see :<\/p>\n\n\n\n

Updated indicators<\/li>\n<\/ul>\n\n\n\n

\n\n\n\n

<\/span>Step 1: Filter data interactively<\/span><\/h3>\n\n\n\n

Then click on the filter form icon.<\/li>\n<\/ul>\n\n\n\n

The fields will appear with the widgets defined (single values, date range…). Select the desired values and click on \u201cApply filter\u201d.<\/p>\n\n\n\n

This filter does not directly modify the map, but you can :<\/p>\n\n\n\n

use only the entities selected in Data Plotly,<\/li>\n\n\n\n

or create a virtual layer with a SELECT * FROM releves_waste WHERE ….<\/li>\n<\/ul>\n\n\n\n

\n\n\n\n

<\/span>Step 2: create an interactive chart with Data Plotly<\/span><\/h3>\n\n\n\n

Configure :\n

Check Use only selected features if you are filtering via the table.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n

As soon as you modify the filter or select other features, the graph is updated.<\/p>\n\n\n\n

\n\n\n\n

<\/span>Step 3: Display dynamic indicators with labels<\/span><\/h3>\n\n\n\n

To avoid complex scripts or temporary views, QGIS lets you display dynamic statistics directly on the map, in the form of labels attached to features.<\/p>\n\n\n\n

<\/span>Objective<\/span><\/h4>\n\n\n\n

Display, for selected features only :<\/p>\n\n\n\n

Beach name<\/li>\n\n\n\n

Total waste observed on this range<\/li>\n<\/ul>\n\n\n\n

<\/span>Method<\/span><\/h4>\n\n\n\n

Activate labels on your layer.<\/li>\n\n\n\n

In the label expression, use :<\/li>\n<\/ul>\n\n\n

<\/div>

<\/div><\/div>

<\/p>\n\n\n\n

if(\n  is_selected(),\n  \"plage\"  || '\\n'  ||  \n  'Total d\u00e9chets : ' || \n  aggregate(\n    'suivi_plages_dechets',\n    'sum',\n    \"quantite\",\n    filter:= \"plage\" = attribute(@parent, 'plage')\n  ),\n  ''\n)\n<\/code><\/pre>\n\n\n\n<\/div><\/div>\n\n\n\n
This expression checks whether the range is selected (is_selected()), then displays :<\/p>\n\n\n\n
\nIts name<\/li>\n\n\n\n
The sum of waste for this range, calculated dynamically via aggregate().<\/li>\n<\/ul>\n\n\n\n<\/span>Result<\/span><\/h4>\n\n\n\nWhen you select one or more ranges, the label is displayed only on those selected, with their respective waste totals.<\/p>\n\n\n\n
\n\n\n\n<\/span>Variant (optional)<\/span><\/h3>\n\n\n\nYou can also filter via the attribute table or a search form, and the labels will react automatically to the selection.<\/p>\n\n\n\n