1

I'm tasked with displaying reserve data on a map but also displaying the category data for each site even though they overlap with other reserves. E.g. I have a category, "Birdwatching" which applies to 50 sites whilst the category, "Grassland" applies to 30 sites but overlaps with the birdwatching category thus a site could have "birdwatching and grasslands".

I created a layer for every category, so a user could select "birdwatching" and view the 50 of 100 reserves that meet this rule. But how do I go about composing a map that includes all ten categories?

  • Take a look at the options for "fill style" for your layer symbology. You can either choose some kind of point or line-based fill, or adjust transparency levels so that other layers will show through. – JoshC Mar 17 '18 at 14:07
1

The OP suggests that the sites across the 10 layers are the same and a single site can be a grassland and a bird watching site at the same time.

The solution to this is not to create a layer for every category but rather have one layer and create a column for every category and fill it with 1 if the site belongs to this category and 0 if not. Then you could represent the sites using the rule-based styling.

Edit:

Based on an additional comment by the OP, a good option to represent the attributes of the sites is to use Layer Diagram Options in QGIS (Second button on the label toolbar). Using a rule-based symbology with 10 attributes can potentially create lots of classes.

enter image description here

You have the option to represent the data as:

  • A pie chart

enter image description here

  • Text diagram

enter image description here

  • Histogram

enter image description here

The tool settings are rather straightforward to use.

  • This is something I also considered (data is already displayed yes/no) but i'm confounded by how to compose a map that displays this information as that is part of my instructions. I understand how a GIS interface could answer the question, E.g. User selects the categories they are interested in then it shows relevant sites but I don't know how show that on a single or multiple maps for the sake of a report. Is it possible to have a symbol segmented based on the number of categories for that site? – McGraw Mar 18 '18 at 9:09
  • This seems like a solution but QGIS crashes each time I select the categories. I reduced it two categories and it created the pie chart but it was not filled in for any of the sites. – McGraw Mar 19 '18 at 9:35
  • Did you add the attributes to the assigned attributes? – Techie_Gus Mar 19 '18 at 10:00
  • I completed the following: Selected layer>diagram options>pie chart>selected the 10 attributes from available attributes>clicked green cross to place them into assigned attributes>clicked ok> layer appears with circle over each node but no segments>qgis crashes. – McGraw Mar 19 '18 at 11:28
  • 1
    Can't argue with that. – McGraw Mar 19 '18 at 11:50
1

You need to use rule based styling to use more then one category. There are many online tips guides and tutorials on rule based styling in qgis.

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.