{"id":14955,"date":"2025-08-18T10:00:00","date_gmt":"2025-08-18T08:00:00","guid":{"rendered":"https:\/\/www.sigterritoires.fr\/?p=14955"},"modified":"2025-08-07T15:13:56","modified_gmt":"2025-08-07T13:13:56","slug":"associating-points-with-their-municipality-or-zone-simple-spatial-joins-with-mmqgis","status":"publish","type":"post","link":"https:\/\/www.sigterritoires.fr\/index.php\/en\/associating-points-with-their-municipality-or-zone-simple-spatial-joins-with-mmqgis\/","title":{"rendered":"Associating points with their municipality or zone: simple spatial joins with MMQGIS"},"content":{"rendered":"\n

When you have a layer of points (field surveys, geocoded addresses, incidents, observations, etc.) and a polygon layer (municipalities, sectors, zones), it is often useful to know which zone each point is located in.<\/p>\n\n\n\n

This is what a spatial join allows you to do. And with the MMQGIS plugin, you can do it in just a few clicks, without writing a single line of code.<\/p>\n\n\n\n

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

Objective<\/a><\/li>
Required data<\/a><\/li>
Steps in QGIS<\/a><\/li>
Result<\/a><\/li>
Best practices<\/a><\/li>
Concrete example<\/a><\/li><\/ul><\/nav><\/div>\n
<\/span>Objective<\/span><\/h2>\n\n\n\n
For each point, add descriptive information from the polygon in which it is located: name of the municipality, sector, INSEE code, etc.<\/p>\n\n\n\n
\n\n\n\n
<\/span>Required data<\/span><\/h2>\n\n\n\n
- A point layer (Shapefile<\/a>, GeoPackage<\/a>, or geocoded CSV<\/a> format).<\/li>\n\n\n\n
- A polygon layer containing the attribute to be reported (e.g., municipality_name, zone_code, etc.).<\/li>\n<\/ul>\n\n\n\n
  Both layers must be in the same coordinate system (ideally EPSG:4326<\/a> or EPSG:2154 for France).<\/p>\n\n\n\n
  \n\n\n\n
  <\/span>Steps in QGIS<\/span><\/h2>\n\n\n\n
  \n
  Open both layers in QGIS (points + polygons).<\/li>\n\n\n\n
  Menu:\n
  \n
  MMQGIS \u2192 Combine \u2192 Spatial Join<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n
  \n
  $\"\"$ <\/a><\/figure>\n<\/div>\n\n\n
  \n
  In the dialog box:\n
  \n
  Target Layer = point layer (the one that will receive the attribute).<\/li>\n\n\n\n
  Join Layer = polygon layer (the one that contains the attributes to be added).<\/li>\n\n\n\n
  Field Operation = First (\u201cTake attributes of first matching feature\u201d).<\/li>\n\n\n\n
  Select the fields to retrieve (e.g., municipality_name).<\/li>\n\n\n\n
  Specify an output file (shapefile or other).<\/li>\n<\/ul>\n<\/li>\n\n\n\n
  Click OK.<\/li>\n<\/ol>\n\n\n
  \n
  $\"\"$ <\/a><\/figure>\n<\/div>\n\n\n
  \n\n\n\n
  <\/span>Result<\/span><\/h2>\n\n\n\n
  A new enriched point layer appears. Each point now contains one or more additional fields from the polygon in which it is located.<\/p>\n\n\n\n
  \n\n\n\n
  <\/span>Best practices<\/span><\/h2>\n\n\n\n
  \n
  If a point does not fall within any polygon, the added fields will remain empty. Remember to check for \u201cout of zone\u201d cases.<\/li>\n\n\n\n
  You can choose to add the first intersecting polygon or all of them (but MMQGIS only handles one match per point).<\/li>\n\n\n\n
  For complex cases (points in multiple areas, overlaps), the QGIS Processing Toolbox offers more options (including \u201cJoin attributes by location (summary)\u201d).<\/li>\n<\/ul>\n\n\n\n
  \n\n\n\n
  <\/span>Concrete example<\/span><\/h2>\n\n\n\n
  You have:<\/p>\n\n\n\n
  \n
  schools (points),<\/li>\n<\/ul>\n\n\n\n
  $\"\"$ <\/a><\/figure>\n\n\n\n
  \n
  municipalities (polygons).<\/li>\n<\/ul>\n\n\n\n
  $\"\"$ <\/a><\/figure>\n\n\n\n
  After spatial joining, each school carries the attribute fields of the municipalities, which is useful for:<\/p>\n\n\n\n
  \n
  grouping data,<\/li>\n\n\n\n
  creating thematic maps,<\/li>\n\n\n\n
  generating reports by municipality.<\/li>\n<\/ul>\n\n\n\n
  $\"\"$ <\/a><\/figure>\n\n\n\n
  \n\n\n\n
  <\/p>\n","protected":false},"excerpt":{"rendered":"
  When you have a layer of points (field surveys, geocoded addresses, incidents, observations, etc.) and a polygon layer (municipalities, sectors, zones), it is often useful to know which zone each point is located in. This is…<\/p>\n","protected":false},"author":1,"featured_media":14839,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[3394,1377],"tags":[1435,3542,1758,1386,2763],"class_list":["post-14955","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-pluigin-en","category-qgis-en","tag-join","tag-mmqgis-en","tag-plugin-en","tag-qgis-en","tag-spatial-en"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t