2

I have installed QGIS 2.12 Lyon and I need to dissolve multiple polygons according to one column in the dbf file (my layer is a shapefile).

I have used SAGA "Polygon dissolve by attribute" algorithm and it works OK. The issue is that in my original file I have 7 columns, one of which is used to dissolve the polygons. The dbf file of the new layer has only 1 field - the one used to dissolve polygons.

How do I force SAGA to keep my other fields?

I just need one entry for each new polygon - information is repeated anyway.

Using the interface I could not see any option to select a method to retain information for other fields.

  • What if the other columns have different contents? Should the values be written as comma separated list or what? – user30184 Nov 6 '15 at 17:35
  • Hi. For this specific set of data I did not mind, since I knew that all those fields had repeated values for the same dissolving records. Ideally there should be a list of different options depending on the field type. For example, for a string there should be: first, last, max, min, distinct list, full list, count. For numeric, I would expect min, max, sum, mean, median, count. – Michele Nov 10 '15 at 21:52
1

Not exactly what I wanted but it's a workaround. I have imported both layers in QGIS. On my new layer I selected "Properties", then selected "Joins". I have added a new Join and set up as: Join layer: old layer Join field: field used to dissolve polygons Target field: the only field in the table Choose which field are joined: checked the box and selected few fields from the original file.

Clicked OK and my new layer dbf file has additional fields.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.