Questions tagged [array]
An arrangement of quantities, symbols or objects in rows and columns; a matrix
21
questions
4
votes
1
answer
1k
views
Using PostGIS to find the overall difference between two (large) polygon datasets
I need to get the Difference of an input layer with ~30k polygons and an overlay layer with ~500k polygons (of which ~200k intersect the input layer).
I am trying to learn PostGIS to do this, as it ...
- 155
4
votes
3
answers
9k
views
Editing .tiff rasters in Python
I am trying to edit .tif rasters in python, but I have some issues regarding the tiff to array conversion.
I read there are multiple options for opening rasters (gdal, PIL, matplotlib), but which of ...
- 338
10
votes
2
answers
13k
views
Optimizing Python GDAL ReadAsArray
I am using the GDAL ReadAsArray method to work with raster data using numpy (specifically reclassification). As my rasters are large, I process the arrays in blocks, iterating though each block and ...
- 327
7
votes
3
answers
14k
views
Is it possible to open rasters as array in NumPy without using another library?
I know that it is possible to open a raster as an array in NumPy using GDAL, but I want to skip GDAL and use NumPy only, as it is cooler handling rasters with NumPy as matrices.
There is a similar ...
- 1,545
3
votes
1
answer
531
views
Automatically create an array of all visible layer names in QGIS
How can I get an array of all visible layer names automatically using QGIS expressions? In principle it should work with the variable @map_layers. Using the following expression works fine for what I ...
- 71.2k
1
vote
0
answers
1k
views
reading raster without making QGIS apply the scale factor to the raster
Since QGIS multiplies the image with the scale factor when reading, it messes up the image if the scale factor is not properly defined to the data as QGIS expected. For example, I am reading MODIS ...
- 139
12
votes
3
answers
704
views
Handling multiple selections result in "Value Relation Widget" in QGIS
Using the "Allow multiple selections" in the "Value Relation Widget" results in {value1,value2,...}. But arrays in QGIS are written like ['value1','value2',...].
How do I handle ...
- 8,262
5
votes
2
answers
129
views
How can cumulative point data be labelled in QGIS?
With the following code I can generate a listing. However, the entire list is displayed and not the data of the attribute of the respective geometry.
'Schäden: '||
array_to_string(
array_agg(
&...
- 71
4
votes
1
answer
4k
views
Select features matching the values in an array (QGIS 3.10 expression)
I want to use an expression to select features matching the values of an array.
Select features from a list is done by the IN operator:
"field" IN ('value1','value2')
But how to select features ...
- 8,262
4
votes
1
answer
468
views
How to sort multi-column lists by first or second column in Google Earth Engine
I have a list with two-segment.
var list = ee.List([
[101, 102],
[102, 103],
[103, 104],
[106, 100],
[104, 105],
[105, 106],
])
How can sort this list by first or second column?
3
votes
2
answers
127
views
QGIS Field Calculator Expression to retrieve index of specific value
I have two tables:
[see image beloW]
HAK where the Column "Volumenstrom_h" has the input value ( x ) needed for the linear interpolation formula displayed which can be seen surrounded by ...
- 161
3
votes
1
answer
326
views
QGIS expressions: remove several elements at once from an array
The problem
Using QGIS expressions with QGIS 3.20, I have an array and I want to exclude a number of elements from this array. Let's say my array is [1,2,3,4,5,6], but I want to get an array like [1,2,...
- 71.2k
3
votes
1
answer
374
views
Create Array From Selected Features Based on the Order in Which They Were Selected
I need to create an array of features from a selection based on the order in which they were selected.
As in: I select feature 5,2,3,4. I need to have an array so I can apply attributes (with python) ...
- 4,387
3
votes
1
answer
2k
views
Methods for converting a regular polygon grid to a numpy array
I have a regularly spaced model grid, 5000 by 5000 feet (517,300 cells), which I need to convert to a numpy array. I am investigation a couple of different methods, using arcpy, by which I can convert ...
- 4,321
3
votes
3
answers
1k
views
Creating polygon from 2 txt files (Parent ID + Coordinates) using ArcPy?
I want to create polygons based on two separate text files:
the first one (as parents) lists the Polygon ID (ID_el) and three to four Points ID (IDpt1, IDpt2, IDpt3..)
the second contains the Points ...
- 407
2
votes
1
answer
973
views
Get data from a raster using two coordinate arrays with Python
I'm trying to find a function in Python, that given two arrays with geographic coordinates, returns a list or array of raster values in those positions. that is to say:
import numpy as np
""&...
2
votes
1
answer
356
views
Determining proportion of raster cells containing each value from list for many rasters in raster stack?
I wrote a function to determine the proportion of raster pixels that contain each of a list of values that I would be interested in. I then wrote a function to apply the previous function to a 3d ...
- 103
2
votes
2
answers
5k
views
How do I sort a geoJSON feature collection alphabetically by a property value?
I am trying to sort the objects in a geoJSON FeatureCollection alphabetically by the values of one of their properties. How do I get to the nested object properties with JavaScript? I have tried using ...
- 21
2
votes
1
answer
851
views
Can I view a Postgis Geometry Array in QGIS?
I've got an array of geometry as a column in a postgis database. Is it possible to view the data (even the n'th element?) in qgis?
- 55
1
vote
1
answer
134
views
Error with array_foreach when using together with aggregate in QGIS expression [closed]
I want to use array_foreach functionality. But it does not seems to work when used in an aggregate function.
This intermediate test ( array predefined, instead of array generated by another aggregate),...
- 630
1
vote
1
answer
964
views
Importing gdal_array from gdal in Conda
I'm working through python examples in a geospatial book using jupyter notebook and have run into trouble trying to import gdal_array from my gdal installation. I've seen several old questions and ...
- 437