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I'm trying to show (in QGIS) how the distribution of 7 or 8 different attributes of a given shapefile vary across polygons within the layer.

For a given attribute, this is simple (well, the basics are): use a categorized or graduated style to show which polygons are high- and which are low-intensity in the attribute.

Because I've no formal background in GIS-ing, I'd like to know what the most common/straightforward way to do this several times.

Right now my approach is to bring in 7-8 copies of the layer into the ?layer space?, and repeat the process on each of the layer copies--so that in the end I have 7 (identical except for aesthetic style) copies of the original layer, each colored according to one attribute.

Then, I bring them all in to the print composer one-by-one and use subtitles to distinguish them.

This seems somewhat inefficient to me, so I wanted to reach out to SE to see if there are any recommendations for a speedier approach to scaling up the process of illustrating attribute distributions in a shapefile.

Compounding the issue is that the base layer doesn't have the attributes--I'm bringing them in via an attribute join, so I have to re-join the table to each layer copy.

I thought of re-saving the layer once the table's joined, but I'm hoping there's a better way--the table being joined is still sort of dynamic (early in development) so it's likely to evolve (if slightly) as analysis progresses. This is a slight improvement on my current approach (only re-save the layer once if the table updates, as opposed to re-join the table 7 times), but I'm on the look out for something more drastic.

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  • I tried doing that--what do you mean by copy? What I meant was to re-add the shapefile 7 times. See edit about re-saving Feb 6, 2015 at 21:34
  • ah! yes indeed. for reference that procedure in QGIS is called Duplicate and is accessible from a layer TOC right click or the Layer menu. That makes it much easier; I think the only scope for improvement is through Python scripting (which I'm open to try if someone is willing to offer some help). Feb 6, 2015 at 22:28
  • Yea, that's typical--same functions, different names. I'm cursing my eyes for skipping over it so many times. Feb 6, 2015 at 23:36

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To turn this in to a proper answer and clean up the comments a bit, one time saving method I use is to add the data set first as one layer and get the symbology set up on the first field the way I want it. Then I copy that layer, or in QGIS terms Duplicate it, as many times as I need for the other attributes. By going in to the symbology of each layer and just changing the field that symbology is based on, I don't have to set up the symbology each time. Nor would I have to redo a Join.

In ArcGIS, if the illustrations are to be on the same page, then you can use the same trick in the layout. Get one view framed as you like it, copy that view/dataframe as many times as needed, and turn off all but one layer in each one. Not sure if QGIS would allow this workflow in Print Composer. So far as I know, neither program lets you have multiple pages in a single layout except in certain circumstances (like Data Driven Pages) that wouldn't work for what you're doing. I usually create a template file in that case, and save a copy for each attribute rather than creating duplicate layers.

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