Contents
How to iterate over layers in pyqgis Python?
Then you can iterate over layers like: Because .mapLayers () returns a dictionary ( dict ), you can also use .values () method of dictionary which returns just a list which contains layers in that case. Then you can iterate over layers like: Note: After grouping I have to remove the duplicate layer so I used root.removeLayer (lyr).
How to traverse a list in reverse order in Python?
To use negative indices: start at -1 and step back by -1 at each iteration. To access the index as though you were iterating forward over a reversed copy of the collection, use i – 1: Assuming task is to find last element that satisfies some condition in a list (i.e. first when looking backwards), I’m getting following numbers:
Is there a reverse list function in Python 3?
Obviously, the reversed limitations still apply. Also, you could use either “range” or “count” functions. As follows: In python 3, list creates a copy, so reversed (list (enumerate (collection)) could be inefficient, generating yet an other list is not optimized away.
Which is the fastest way to traverse a list in reverse order?
Assuming task is to find last element that satisfies some condition in a list (i.e. first when looking backwards), I’m getting following numbers: So, the ugliest option xrange (len (xs)-1,-1,-1) is the fastest.
How to run a QGIS processing algorithm in Python?
You can also run a QGIS Processing algorithm via Python using the processing.runAndLoadResults () function instead of processing.run () as shown above – which will load the result to QGIS canvas directly.
Is there any new way to iterate selected vectors?
I used to be able to iterate over selected features using the following script in v2.0. However, this doesn’t seem to work when I upgraded my QGIS to v2.2. Is there any new way on how to iterate selected vectors? But if you look at what’s in the module (version 2.2):
How to load a.bil file in QGIS?
Each layer is presented with a set of files .bil file containing the actual data, a .hdr file describing the data structure and a .prj file containing the projection information. QGIS can load the .bil file and provided the other files exist in the same directory.
Do you need to loop through layers in GIS?
For many GIS operations you need to loop through the map layers to look for specific information or to apply a change to all layers. In this recipe, we’ll loop through the layers and get information about them. We’ll need two layers in the same map projection to perform this recipe.
How to create dynamic maps in QGIS Python?
This section of the preview chapter, Creating Dynamic Maps from QGIS Python Programming CookBook takes a look at how to control an object through the Map Canvas, change map units, and how to loop through map layers.
When to change the map units in GIS?
The most common use case for changing map units is to switch between imperial and metric units depending on the user’s preference. For many GIS operations you need to loop through the map layers to look for specific information or to apply a change to all layers. In this recipe, we’ll loop through the layers and get information about them.