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Select points with maximum value in each polygon

I have Census areas as polygons and Census population counts as points at a lower geographic level (i.e., there are many points within each polygon). I need to select 1 point from within each polygon ...
Thomas Hochkins's user avatar
0 votes
1 answer
27 views

Create a point that represents the maximum raster value (elevation) within a polygon: Google Earth Engine

I have around 300 polygons spread across a large area and wish to create a set of points, one for each polygon, that represents the maximum elevation value along the edge (or within) the polygon. I ...
Erin's user avatar
  • 157
2 votes
1 answer
167 views

Finding maximum possible distance of point to polygon boundary using QGIS Expression

Points layer is structured as below Polygons layer also has code as a field For each point, I want to get maximum possible distance to the edge of the polygons listed with code in the overlap column. ...
Alexander B's user avatar
4 votes
3 answers
769 views

Zooming to maximum raster cell value in QGIS

I have a Float 64 TIFF in QGIS that has greater than 500 million cells. Without converting to a point layer, is there a way to zoom to the cell that contains the maximum value? I have looked at ...
Dunner's user avatar
  • 43
3 votes
2 answers
258 views

Combination of maximum values in QGIS

I'm making classification by rules to create a map with different colors; I have 4 values (A,B,C,D) assigned to some areas and I want to find the maximum values between the four in each area. Thus, I ...
Mark's user avatar
  • 33
0 votes
0 answers
69 views

Maximum value for the GCI index is not correct

I'm working with QGIS 3.28.6 software. I have calculated the GCI index using a raster calculator. The formula used GCI = (NIR/GREEN)-1. Unfortunately, the max values obtained are not in the range ...
xavier's user avatar
  • 1
0 votes
0 answers
43 views

How to create a surface from a raster which goes through all the local maximum altitudes of my raster using QGIS?

I am struggling to create a surface from a raster using QGIS. The surface needs to go through all local maximum altitudes of my raster (tangent to vertices) and needs to have some kind of smoothed ...
PARISI's user avatar
  • 9
5 votes
2 answers
200 views

Finding field containing maximum value for each row in QGIS

I have a table with the number of buildings constructed per time period in each district, and I would like to determine the time period in which most buildings were built. For example, for the ...
cyirand's user avatar
  • 95
3 votes
2 answers
403 views

Selecting the maximum value from series of polygons that intersect with line in QGIS

Is there a way to select the cell (single) with the maximum value in a polygon layer using the intersection of a line? The first image is the grid (polygon) layer with the attribute field "VALUE&...
Anthony's user avatar
  • 127
1 vote
1 answer
506 views

Google Earth Engine - Get Image with highest max Scene NDWI

By adapting code from Getting Image with highest max Scene NDVI from Image collection using Google Earth Engine I have been able to make a script that gives me the date and mean highest NDVI for each ...
willbutdontwanna's user avatar
0 votes
1 answer
162 views

Finding maximum value on raster transect between two points using PyQGIS

I have a raster layer and two points with their coordinates, and I want to find the maximum raster value on the line between these two points. Is there a built-in function in PyQGIS to find the pixel ...
S.E.'s user avatar
  • 336
1 vote
1 answer
208 views

Google Earth Engine - Get Image with lowest NDVI from a time period

One of the answers to this question (Google Earth Engine - Get Image with highest max Scene NDVI from a time period) provides code which gives a Sentinel image/date with the highest NDVI for each ...
willbutdontwanna's user avatar
3 votes
2 answers
802 views

Getting polygon with max attribute within polygons with same geometry using GeoPandas

I have a GeoDataframe containing the spatially joined result of a square grid map and flood hazard data. However, there are instances of rows with the same "geometry" but differing "...
SS-Salt's user avatar
  • 139
5 votes
1 answer
452 views

Creating longest line within polygon that crosses point

I am performing a morphometric analysis of dolines using QGIS. I want to generate longest axis within basin polygon that crosses the lowest point (from other layer) of basin. Is there a way to ...
Arief's user avatar
  • 83
5 votes
6 answers
2k views

Returning column name of the max value in QGIS

I am working with some age group data in QGIS based on point counts within a polygon grid and I would like to calculate the max value from a row with 11 different age groups in order to get the ...
John's user avatar
  • 81
5 votes
2 answers
1k views

Selecting features by expression with SQL syntax in QGIS

I have a table (shapefile) in QGIS where I want to select features that satisfies this condition: group by a field ("join_label") and within the "grouped field", pick the attribute ...
AchB's user avatar
  • 131
6 votes
2 answers
655 views

Finding the longest horizontal line inside polygon in QGIS

I have a state polygon like the pic shown below, is there a way to find the line which is the maximum horizontal line? Like this, but I want the maximum distance line.
Anand's user avatar
  • 79
2 votes
1 answer
38 views

Replace a field with maximum of it's attribute values based on values repeated on another field's attribute values using ArcPy

So I have performed Spatial Join between a point and line feature class. Now for each point there are several lines. What I want is the maximum count of line features as an attribute value in the &...
soumik chakraborty's user avatar
4 votes
2 answers
714 views

Using max function to group max value by unique ID in QGIS

I have been using the maximum function to group max value by unique "id"; maximum("Ni_ppm_1", group_by:="Hole_id") The function pulls the maximum "Ni_ppm_1" ...
Donny's user avatar
  • 93
2 votes
2 answers
246 views

Getting maximum value of measured values ​every xx meters

I have huge CSV files from measurements (most of them are done by car), like this: measurement file The measurement system record one value every second and save this together with the GPS coordinates....
Peter's user avatar
  • 61
6 votes
1 answer
575 views

Placing point over pixel with maximum value falling in grid overlay using QGIS

I have a raster layer with a Shapefile grid with cells measuring 3 x 3 m overlaid on top. All I want to do is find the pixel with the maximum value within each cell, and place a Shapefile point over ...
Jesse's user avatar
  • 207
0 votes
1 answer
115 views

Getting maximum distance for point features in the same point group

For each group I want to find the maximum point-to-point distance (and which of the id1 features participate in the max). For example, if I have the following attribute table: FID Long Lat id1 ...
a11's user avatar
  • 950
1 vote
1 answer
429 views

Showing only maximum value for each point feature

I have a dataset with concentrations of copper from different stations taken over several years. I would like to show only the highest concentration "mikromolar" for each station "STATN&...
Linda's user avatar
  • 21
9 votes
3 answers
2k views

Finding longest straight line within polygon in QGIS

I'm looking for an algorithm to draw max distance straight lines contained in a polygon (without crossing polygon boundaries). How can I perform it? As you can see some polygons are very oddly shaped. ...
Michael Sousa's user avatar
2 votes
2 answers
1k views

Google Earth Engine - Get Image with highest max Scene NDVI from a time period

I have a shapefile with several fields, corresponding to different wheat fields of a certain year. Using as Input an image collection converted to NDVIs, I would like to calculate the mean NDVI value ...
Alfonso de Lara's user avatar
14 votes
4 answers
4k views

Calculating line with the longest distance inside polygon in QGIS

I want to calculate the "diameter" of polygons in QGIS. The "diameter" is defined as the distance between the two most distant points of the polygon. I couldn't find a fitting ...
gis_student's user avatar
13 votes
4 answers
4k views

Maximum value of field of vector layer using PyQGIS

If I have a vector layer in QGIS, how do I use Python to find the maximum value which a given field has? I need to convert the values in one field into values between 0 and 1. I guess I therefore need ...
Tom Chadwin's user avatar
  • 5,862
3 votes
0 answers
381 views

Centering map on maximum value of raster in QGIS [duplicate]

I have a very large QGIS raster layer showing the differences between two nearly identical rasters. Because of this, it is very difficult to find where in this layer the few pixels that are different ...
Richard's user avatar
  • 1,831
7 votes
3 answers
8k views

Using 'max()' in expression with QGIS

I want to make a rule-based style on the maximum value from a field. I set my expression like: max("fieldname") It returns every value instead of only the maximum one. Can anyone tell me ...
PieterB's user avatar
  • 5,287
5 votes
3 answers
3k views

Determining the longest side of polygon in QGIS

Is there a possibility to determine the longest side of a polygon with QGIS? As I need to do that for hundreds of polygons I would prefer an automized method (like a plugin). So far my idea was: ...
ragavendra's user avatar