[Qgis-user] Group Statistics Tool

[Nicolas Cadieux]

Hi,

This is like a cross tab or a pivot table in Excel. You need to place the polygon layer in the column field.

https://anitagraser.com/2013/02/02/group-stats-tutorial/

Nicolas Cadieux
https://gitlab.com/njacadieux

> Le 18 juill. 2021 à 12:47, krishna Ayyala <ayyalakrishna at gmail.com> a écrit :
> 
> 
> Nicolas,
> Thanks for your reply.They are not multi polygons. They are two separate polygons. That means A with area 60 is one polygon and A with area 30 is second polygon. If I select one polygon on the map, only one polygon gets highlighted. But, in group stats ,I have selected the first row which is A 60. I clicked "Features" and then "Show selected on map" both the polygons on the map are getting highlighted. As I mentioned before, only one polygon should get highlighted. If I create a unique id, that will not serve the purpose. I am trying to derive the polygon with maximum area  from the list of polygons that are labeled as A.
> 
> Regards.
> 
>> On Sun, Jul 18, 2021 at 9:58 AM Nicolas Cadieux <njacadieux.gitlab at gmail.com> wrote:
>> Hi,
>> 
>> I do you have multipolygons in your input files?  If not, perhaps the multipolygon is being created because both polygon have the same ID, A.  Try creating a unique id field to see what is going on.  A multipolygon or multipart object will contain multiple polygons but only one data line in the data table. You can split multipolygon with a «multiple to single »tool found in the vector menu.
>> 
>> Nicolas Cadieux
>> https://gitlab.com/njacadieux
>> 
>>>> Le 17 juill. 2021 à 20:56, krishna Ayyala <ayyalakrishna at gmail.com> a écrit :
>>>> 
>>> 
>>> Hello,
>>> I have a polygon shape file with an attribute table as shown below.
>>> 
>>> <image.png>
>>> 
>>> 
>>> I am using the Group stats tool to derive only those rows that have max area for each polygon. After clicking calculate, I got the results below. In the below window. I have selected the first row which A 60. I clicked "Features" and then "Show selected on map" . Technically, it is supposed to highlight only one polygon which is A with an area 60 on the map. But is highlighting both the polygons i.e..A with an area 60 and also A with an area 30. Is there a way to select only the polygon A with an area 60?
>>> 
>>> <image.png>
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
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