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QGIS is a free, open source, cross platform (lin/win/mac) geographical information system (GIS)
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zonal statistics #3326

Closed qissue-bot closed 5 years ago

qissue-bot commented 5 years ago

Author Name: flo - (flo -) Original Redmine Issue: 3338, https://issues.qgis.org/issues/3338

Original Assignee: Marco Hugentobler

A zonal statistics plugin would be great. It would allow to extract raster statistics with a vector layer : mean raster value for each vector features (polygon, line or point), and also standard deviation, median...

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Giovanni Manghi (Giovanni Manghi) Original Date: 2010-12-15T07:27:03.000Z

meanwhile you have zonal statistics trough the GRASS plugin.

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: flo - (flo -) Original Date: 2010-12-15T07:38:08.000Z

Replying to [comment:1 lutra]:

meanwhile you have zonal statistics trough the GRASS plugin.

Thank you for your answer, I use also Grass. However, I think it's an "usual" GIS task, and it would be more convenient if it could be directly done in Qgis, without Grass. Moreover, I think the zonal stat in Grass takes a lot of time to compute statistics (in comparison with Arcgis).

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Borys Jurgiel (Borys Jurgiel) Original Date: 2010-12-15T11:45:30.000Z

Could you please add this idea to http://www.qgis.org/wiki/Python_Plugin_Ideas ? We set that page over a year ago, so let's start using it! :)

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Marco Hugentobler (Marco Hugentobler) Original Date: 2010-12-15T23:06:28.000Z

There is a zonal statistic function in the analysis library (analysis/vector/qgszonalstatistics.cpp/.h). I've wrote the function and a plugin because GRASS was too slow for my needs. However, also the function in the analysis lib is still far from optimal performance and follows a 'naive' approach. That's why I didn't commit the (GUI) plugin to trunk.

If you are interested in using the plugin, go to http://www.sourcepole.com/2010/12/16/zonal-statistics-plugin-for-qgis and download the source. It is explained on the page how to recompile.

Regards, Marco

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Giovanni Manghi (Giovanni Manghi) Original Date: 2010-12-16T03:23:26.000Z

Hi Marco, is really that bad? ;)

I would not mind to have even a sub optimal solution in QGIS and then have it upgraded when possible in the future...

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: flo - (flo -) Original Date: 2010-12-20T00:22:21.000Z

Thank you for this function. I've tested it and it seems to work fine ! Couldn't it be by default in Qgis ?

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Paolo Cavallini (Paolo Cavallini) Original Date: 2011-08-11T03:29:06.000Z

I understand it has been added to Windows build - please add it also to debs

qissue-bot commented 5 years ago

Original Redmine Comment Author Name: Jürgen Fischer (Jürgen Fischer) Original Date: 2011-08-11T11:51:46.000Z

fixed in commit:880540baac7fcbbf4217556ca8b251d3cee47ad5