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Hei!

I got shapefile with 1800 points. They are classified by attribute in 10 classes. How can I display only 1 or 2 classes (like - switch on/off layer)?

It seems quite usual function, but I couldnt find such option in QGIS. The only solution witch I could figure out, is to make 10 different shapefiles for each class.

Thanks!

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2 Answers

up vote 4 down vote accepted

You certainly don't need 10 different shapefiles.

You can load the same shapefile 10 times (into 10 different layers) and use the query definition (in Layer Properties - General tab) to define the class. Then you can turn the layers off and on as you like. This takes a little time to set it up but at least it does not clutter your harddrive with million shapefiles.

Another solution would be to use a rule-based renderer where you can adjust the query that defines the classes that are drawn.

enter image description here

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Thanks for the tip. Although, at the first moment it looks not so handy to move between classes. –  Oskars May 19 '12 at 8:18
    
@Oskars: added another option –  underdark May 19 '12 at 9:46
    
@Oskars Please consider accepting the answer or clarifying if you need more help. –  underdark May 20 '12 at 10:49
    
This solution, while it is the only one that is feasible with current QGIS, is really sub-sub-optimal. I took the liberty to submit a feature request gis.stackexchange.com/questions/25759/… –  steko Feb 22 '13 at 12:10
1  
Correct link to the QGIS feature request hub.qgis.org/issues/7213 by the way it was much appreciated by several QGIS developers :-) –  steko Feb 23 '13 at 18:45
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Another option is to run a query on the shapefile. You get to the query builder with a right-click on the layer name (in the TOC) and choose Query. Then setup the query such that it reads: [Class_Column] = 'Class'

To display a different class you'll change the query each time.

You can also manipulate the query to display several classes [Class_Column] = 'Class1' OR [Class_Column] = 'Class2' and so on...

Does that get you any closer?

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Not sure I want to make query each time to turn on/off different clases...:) @underdark first suggested option was helpfull. I open 10 the same shapefiles, but instead of making a query in each shape file, I just delete unnecessary class. So I have 10 separate classes (layers), which I can easily turn on/off. And, as mentioned above, this solution doesnt make tonns of shapefiles, because I can do it within 1 shapefile. Maybe it is not logic or whatever, but at least I understand what I am doing and it is easier to explain it for others...as I am using QGIS in master thesis:) –  Oskars May 19 '12 at 17:59
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