QGIS » QGIS Application

Martin Dobias wrote:

Maybe using field calculator would be a better solution rather than adding such functionality directly to categorized symbol renderer? The GUI might get bloated quickly.

so, the suggestion would be to add a function to calculate a new field with all the possible permutations between two or more fields and then use it to style the layer... sounds nice to me!

In any case this was just a suggestion from a Arc* user.

What about just doing a concatenation of ATT1 with ATT2 in a new field and then using categorized symbol renderer on this new field? This should effectively include all existing permutations of those two fields.

Martin Dobias wrote:

What about just doing a concatenation of ATT1 with ATT2 in a new field and then using categorized symbol renderer on this new field? This should effectively include all existing permutations of those two fields.

Hi Martin.

I have doubts now. Concatenating fields it is already possible with the field calculator, like

tostring ( ATT1 )||tostring ( ATT2 )

is this what you mean?

The "problem" is that using two or more fields and making possible permutations of the values, then the permutations number can be very well > then the number of the records in the table of attribute.

If the field calculator way then cannot be used, I suggest a solution to help don't make the symbology GUI too bloated:

on the side of the "column" dropdown in the categorized symbology panel, add a "+" button, exactly as you can see here in Redmine (if you are admin) to allow add categories, versions, etc.

If the user click on this icon, then under the first "column" dropdown, show a second one, and if clicked again a third one (I guess three fields is more than enough).

Hi Giovanni,

The "problem" is that using two or more fields and making possible permutations of the values, then the permutations number can be very well > then the number of the records in the table of attribute.

I don't quite see how this would be true... I think that the number unique registers resulting from concatenating using the field calculator would be the correct ammount of permutations... Thus, the tool/functionality you suggest would just be a shortcut to this concatenating function and perhaps skipping the necessity of a new field in the attributes table. Am I missing something?

I don't quite see how this would be true... I think that the number unique registers resulting from concatenating using the field calculator would be the correct ammount of permutations... Thus, the tool/functionality you suggest would just be a shortcut to this concatenating function and perhaps skipping the necessity of a new field in the attributes table. Am I missing something?

I think you are right.