Questions tagged [calculator]
Related to a "field calculator" interface for modifying field attributes.
2
votes
2answers
55 views
How to get directory from filepath in QGIS action
I have in QGIS layer that contains filepath (e.g. D:/file/28238/pic/D4D3-06_1.png) and I would like to get directory path only like D:/file/new/28238/pic.
Is it possible to do by expression in field ...
-2
votes
0answers
23 views
Filling attributes through a calculator (function editor) by the field value
Help to write for example (only in the function editor)
I need a function Python
What do I need for an example:
if "fclass" = 'water' then "COLOR" = 16 and
if "fclass" = 'water' and "AREA" >= 50 ...
2
votes
1answer
45 views
Batch Raster Calculator
Newbie, tasked with something I think can be done this way, but not sure how to get it to work.
It seems quite simple. I want to subtract a sequence of rasters (daily data): one day from the previous....
0
votes
1answer
92 views
Why does the raster calculator only give out 1 and 0 values
I have a problem with the raster calculator of ArcMap 10.5.1 because it only gives out a raster with 0 an 1 values. I'd like to calculate the Leaf Area Index out of a NDVI-Raster by using this ...
1
vote
1answer
61 views
ArcMap and QGIS Raster Calculator different values
I was carrying out a calculation in raster calculator in ArcMap 10.4 where I multiplied two rasters together. Both rasters had the same extent, were snapped to each other and have the same pixels ...
0
votes
3answers
52 views
If then question with raster calcuator
I have several buffers to be added together (Cold, Hot, Raining, etc.), but they only need to be added if they exist.
So I currently have create buffer if Cold else no buffer. (I did convert polys ...
0
votes
1answer
230 views
Calculating Sequential Field ID For Unique Identifier using Field Calculator
I have a feature class of 7308 features. I have given each feature a unique name (WM-0001 for example) as the FID's jump all over the place. I realized that my new ID's do not match up with the number ...
1
vote
1answer
50 views
Calculating mean between the intersection of two polygons
I need to calculate the mean value (for a specific field of the attribute table) at the intersection of many polygons (.shp). I converted the polygons to raster based on the value I want to use to ...
5
votes
2answers
89 views
Is inverting slope map same as invert surface?
Is it possible to invert a slope map same as invert a surface?
I found code on this website https://support.esri.com/en/technical-article/000006694
The code is following:
(([elevgrd] - Z_Max) * -...
0
votes
1answer
987 views
Using QGIS 3.0 raster calculator?
I have a lesson/class assignment that teaches the use of format and export environmental raster data, but the issue is the lesson is outdated from the new QGIS version.
Lesson states:
Multiply the ...
0
votes
0answers
114 views
Using custom python function with raster calculator
I have a function in a python class that takes two values and returns a third value. I would like to apply the function to two overlapping rasters on a per pixel level and come up with a third raster. ...
2
votes
1answer
48 views
How do I transfer data from one raster to another in qgis
I have 2 raster layers. The first is a mobile signal coverage raster with 0 and 1 values. The second is a population raster with value from 0.89 to 236. I want to transfer the population layer to the ...
0
votes
1answer
142 views
Subtract two DEM to find volumetric change for a glacier without bedrock topography
I am a masters student, and trying to calculate the volume change for a glacier. I have 4 different DEMs, none of them are of the bedrock topography below the glacier. I have read that you can simply ...
6
votes
1answer
432 views
Calculating urban areas that need pharmacies using QGIS?
I'm very new in QGIS.
The task is to calculate the urban areas that has lack of pharmacies.
I have buildings points with apartments count and existing pharmacies points. Then I made two raster ...
2
votes
1answer
168 views
How to use raster calculator to create cumulative ZTV?
I need to create a raster layer with cumulative values for 72 viewsheds.
Each viewshed is from a different point along a line and has been clipped to a 20km buffer from each viewing point.
When I try ...
1
vote
0answers
19 views
QGIS 2.14.8 - Illustrate Multiple Lots [closed]
I am having trouble illustrating multiple properties on QGIS.
Basically I want to illustrate multiple properties/polygons based on their identifying fields - lot and plan.
Can anyone give me an ...
3
votes
2answers
101 views
Copy and transfer only the maximum values of data from one column to another in the field calculator
In the Attribute Table there is a field with the diameter and width of the pipe. I want to transfer all the data from this field to a new field. While in one line there can be several values of the ...
1
vote
1answer
95 views
Syntax to add attributes in a line in the Expression String Builder
I have several columns with certain values, here's an example:
| Apple | Banana| Orange | Pear | Expected result
| 1 | 1 | 1 | 1 | red
| 1 | 2 | 2 | 1 ...
0
votes
1answer
3k views
How to calculate polygon areas in acres or square miles instead of feet?
I have a layer in State Plane NAD83. When I use "Vector|Geometry Tools|Add/export geometry columns" or Field Calculator they both create the area in feet. What if I want acres or square miles? Thanks
...
9
votes
2answers
3k views
How to get latitude /longitude in Degree Minute Second (DMS) using QGIS field calculator?
I have come up with the following expression to convert 5.1234 to 5° 7`24.24"
toint ($x) || '° ' || toint((($x) - toint ($x)) * 60) ||'`' || substr( (tostring(((($x) - toint ($x)) * 60) - toint(...
1
vote
2answers
1k views
How to select only areas bigger than x acres?
I would like to create a new shapefile from another area shapefile. The new shapefile should only contain all areas that are bigger than 5 acres (10.000 m²).
How do I do this?
3
votes
1answer
532 views
Sum up area left “underneath” polygons in QGIS?
I have an area shape layer and multiple other area shape layers. Now I would like to calculate how much space (square kilometers or percentage of area) of the polygons of this area layer is NOT ...
