22
votes
Iterating over map layers using PyQGIS
For QGIS 3, QgsMapLayerRegistry's functionality has been moved to QgsProject.
So, for iterating over map layers, you should use that structure:
layers = QgsProject.instance().mapLayers()
....
- 56.8k
21
votes
Accepted
Mosaicking Image Collection by Date (day) in Google Earth Engine
var poly = /* color: #d63000 */ee.Geometry.Polygon(
[[[-76.0803, 10.8656],
[-76.0913, 7.7436],
[-73.1909, 7.7545],
[-73.3776, 9.4273],
[-75.2124, 10.9304]]])
var start = ...
- 9,336
16
votes
Iterating over map layers using PyQGIS
For QGIS 2.6 here is the code to identify each layer and group them:
#make the desired groups for layers
toc = self.iface.legendInterface()
root = QgsProject.instance().layerTreeRoot()
group1 = root....
- 2,630
13
votes
Accepted
Iterating features and buffering using GeoPandas?
Look at the answer to Updating value in iterrow for pandas:
The rows you get back from iterrows are copies that are no longer
connected to the original data frame, so edits don't change your
...
- 54k
9
votes
Mosaicking Image Collection by Date (day) in Google Earth Engine
Here is another solution that does not involve iterating through days, but maps through unique dates (after removing seconds, microseconds...) that appear in the image collection. It also adds the ...
8
votes
Accepted
Iterating through fields and generating formatted string output
Is this code faster (tested on a 300 features memory layer) :
layer = iface.activeLayer()
# Get name and type of attributes in layer
intfieldsnames = [i.name() for i in layer.fields() if i.type() in [...
- 13k
7
votes
Repeating steps based on different field using ModelBuilder?
There is not an Iterate Fields tool in ModelBuilder.
I can think of two possible workarounds:
Modify the model to run as a Python script. Define a list of the fields you want to use, and define a ...
- 8,926
7
votes
Accepted
Any way to clear selections from features in a map only if they have selected features?
Yes, each Layer has a method called getSelectionSet(), which returns a list of selected OIDs for the layer.
>>> for lyr in arcpy.mapping.ListLayers(mxd):
... if lyr.isFeatureLayer and ...
- 8,384
6
votes
Accepted
repeating steps in GRASS r.mapcalc
You can call r.mapcalc in for loop. In shell it could look like this:
X=5
# initialize first map
r.mapcalc "old = 10"
# loop
for I in `seq $X`
do
r.mapcalc "new = old + 10" --overwrite
g.rename ...
- 731
6
votes
Automate & set layers for PDF maps
You are describing the exact functionality of Data-Driven Pages (DDP), a built-in feature of ArcGIS. You can implement them either in a Python script or in ArcMap. If you've never used them before, I'...
- 12k
6
votes
Accepted
Reading value of point (x, y) in raster and changing its value to another raster using PyQGIS?
To do that is preferable to use a QgsRasterBlock object to get raster values and python GDAL module to write resulting raster values in a new raster. In this case you only need raster1. Complete code ...
- 26.9k
6
votes
Accepted
Iterate over ImageCollection returning pandas dataframe using earth engine & python
Found a solution, by making a list of the scene IDs from the imageCollection and iterating over the list. Then in a loop I import the individual images instead of mapping/iterating over the ...
- 367
6
votes
Accepted
Iterating clip over multiple layers using QGIS?
You can use the Graphical Modeller (Processing menu) to build the desired process. Add as many layers as you like, add your grid, then switch tabs and add a clip-process for each vector-layer and set ...
- 13.2k
6
votes
Accepted
Returning image for each iteration using Google Earth Engine?
Furthermore it appears only 3 items are stored in the list which makes me assume the iteration is more complex than a literal iteration where all images are calculated one by one?
You've got some of ...
- 9,046
6
votes
Accepted
Problems with for iteration in arcpy
In your script, calculate field will compute the values of group for ALL the row (or the selected rows if you used a layer) at each iteration. Therefore the GROUP values for all rows are overwritten ...
- 48.7k
6
votes
Iterate through a list of polygons' centroids in QGIS
In your code, polycent is always set the last polygon's centroid. So you must add centroids to a list.
Change your code into that:
polycents = [] # empty list
for feature in layer.getFeatures():
...
- 56.8k
6
votes
Using RECURSIVE in Virtual Layer
I don't think you need recursive, it looks like you want subtotals for different categories of "DIST_KM"
Does this give something close to want you expect:
SELECT COUNT(*) as anzahl, SUM(FLUX) AS ...
- 1,732
6
votes
Iterating through fields and generating formatted string output
You can also use Refactor fields. Takes ~15 s for a feature class with 44.000 features with 15 integer fields:
lyr = QgsProject.instance().mapLayersByName('sksNaturvardsavtal')[0]
#List all fields ...
- 54k
5
votes
Iterate through features to use selection as input for ExtractByMask
The SearchCursor will return geometries with the SHAPE@ token which can be used as extracting features etc.:
SHAPE@ —A geometry object for the feature.
import arcpy
feature_class = r'C:\test.gdb\...
- 54k
5
votes
Iterating over features in vector layer
Check that the layer is valid. If the layer, or the path is not valid qgis will no raise an error, it will return a QgsVectorLayer object where you can call the methods but with mostly no-op.
layer = ...
- 4,163
5
votes
Iterating raster pairs using ArcPy?
To get started with a Python script you can try code below. ListRasters will sort your rasters by name so if they are named like you say, it should work. Otherwise there are other ways of sorting the ...
- 54k
5
votes
Accepted
Using RECURSIVE in Virtual Layer
With RECURSIVE query, you have to do a generate_series (PostgreSQL function not supported by SQLite), which create you a number series from conf.start to conf.stop by conf.step.
Then, retrieve this ...
- 13k
5
votes
Accepted
arcpy.SelectByAttribute 'Parameters are not valid' error
As the exception states, SelectLayerByAttribute_management expects a layer (which is not the same thing as feature class -fc variable in your case, that you are passing, which is just the data) and ...
- 4,828
5
votes
Accepted
Shortest path (point to point) in iteration, safe for the case there is no route
Try something like that:
n=0
for f1 in layer1:
p1 = f1.geometry().asPoint()
x1, y1 = p1.x(), p1.y()
coord1= f"{x1},{y1}"
for f2 in layer2:
p2 = f2.geometry()....
- 56.8k
5
votes
Iterate over features in a model
I don't know if it is possible using actual options in Modeler or Processing window, but you can make a script doing that.
from qgis.PyQt.QtCore import QCoreApplication
from qgis.core import (...
- 56.8k
4
votes
Iterating over map layers using PyQGIS
Visible layers
You can iterate visible layers in this way:
# Iterate visible layers (warning: only spatial ones)
def iterate_visible_layers():
for layer in iface.mapCanvas().layers():
# ...
- 34k
4
votes
Accepted
Obtaining feature extent while iterating using PyQGIS?
Assuming that layer is your polygon layer, you may use this code:
for feature in layer.getFeatures():
bbox = feature.geometry().boundingBox()
bbox_extent = '%f,%f,%f,%f' % (bbox.xMinimum(), ...
- 15.6k
4
votes
Accepted
Looping and Adding All Feature Classes From File Geodatabase Feature Dataset into Current Map
Take a look at arcpy.ListFeatureClasses() and how that works in a `for loop. See the Code Sample at the bottom of that page.
Then as you loop through the feature classes you just use your same code, ...
- 29.2k
4
votes
Problems with for iteration in arcpy
The problem is in arcpy.CalculateField_management. It overwrite ALL of the field rows when you run it. Using selection will solve this problem but it may cause perfomance problems. To avoid them use ...
- 5,914
4
votes
Problems with for iteration in arcpy
As Mr Che and radouxju have said calculate field does all the rows, and that you should be using an update cursor but I would like to add that you're using an older style of cursor.. the arcpy.da ...
- 25.2k
Only top scored, non community-wiki answers of a minimum length are eligible