# Tag Info

Accepted

### Getting polygon areas using GeoPandas

If the crs of the GeoDataFrame is known (EPSG:4326 unit=degree, here), you don't need Shapely, nor pyproj in your script because GeoPandas uses them). import geopandas as gpd test = gpd.read_file("...
• 55.2k

### Calculate area for each polygon in R

You can do library(raster) x <- shapefile('file.shp') crs(x) x\$area_sqkm <- area(x) / 1000000 Or with terra library(terra) x <- vect('file.shp') x\$area_sqkm <- expanse(x) / 1000000 That ...
• 10.8k
Accepted

### How to calculate the polygon area and create a column of results in R

Can you provide data for an example? Anyways, try this: library(sf) f <- st_read("shapefile.shp") f\$area <- st_area(f) #Take care of units Best
• 958
Accepted

### Calculating area of lat/lon polygons without transformation using GeoPandas

Overview Since version 0.7.0 geopandas has embedded the pyproj library as the crs object. pyproj, since version 2.3.0, has the ability to calculate the area of arbitrary polygons on a sphere. (see ...
• 1,857
Accepted

### Calculate total area of polygons in shapefile using GDAL?

There's a special field in OGR SQL called OGR_GEOM_AREA which returns the area of the feature's geometry: ogrinfo -sql "SELECT SUM(OGR_GEOM_AREA) AS TOTAL_AREA FROM myshapefile" myshapefile.shp ...
• 14.4k
Accepted

### Using area() or \$area function in QGIS, when the data (polygon) is stored in UTM?

The curved surface of the spheroid is unfailingly deformed when taken to the plane. The planimetric area is not equal to the ellipsoidal area. The differences, moreover, are not constant in a ...
• 14.6k
Accepted

### Calculating length of polygon in GeoPandas

Same way as area but: df.geometry.length or df['geometry'].length See GeoSeries.length: Returns a Series containing the length of each geometry.
• 75.2k
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### Why accurate area of all countries cannot be obtained using a single EPSG code, even if it corresponds to an equal-area projection?

What went wrong: EPSG:3395 is not equal area The CRS you use, EPSG:3395, is definitely not an equal area projection. It is a World Mercator projection that heavily distorts areas, see here, including ...
• 73.3k

### Area is calculating wrong using \$area in field calculator (QGIS 2.8.1-Wien)

Use area(\$geometry) instead of \$area According to the QGIS documentation, area(\$geometry) returns the area of a geometry polygon object. Calculations are always planimetric in the Spatial Reference ...
• 151

### Getting polygon areas using GeoPandas

Yes, simply be sure to reproject your shape in Cylindrical equal-area format with {'proj':'cea'} that preserve area measure. Then you can use .area method of your GeoDataFrame. Your also need to ...
• 141

### How does ST_Area in PostGIS work?

SELECT      st_astext(col)     ,st_area(col, false) AS area FROM table ST_Area(geometry) calculates the polygon area as WGS1984, WITHOUT ...

### Calculating percentage of overlap of two layers in QGIS 3

Since QGIS 3.8, it's now included in QGIS core, without plugin or coding. In the Processing Toolbox, search for Overlap and open the Overlap analysis: Source: http://changelog.qgis.org/en/qgis/...
• 7,300

### Calculating polygon areas in shapefile using QGIS

Try using the "Identify Features" tool (Ctrl+Shift+I) from the Attributes Toolbar. There will be two attributes: "Area (Cartesian)" and "Area (Ellipsoidal - EPSG:7019)" ...
• 33.4k

### Calculating polygon areas in shapefile using QGIS

If not getting very accurate area calculations does not bother you (or if you do not want to play with different options in the field calculator as mentioned by some of the answers and comments above),...
• 473
Accepted

### Calculating area of newly added polygons on same layer?

You can use the AutoFields plugin, which solves exactly that issue. Go to the plugin's docked window, select your polygon layer, choose the 'Area' field from the list of existing fields, choose the ...
• 36.7k

### Calculating proportional area of polygon within another layer's polygon using QGIS

Take your model layer and in the attribute table, add a new field called area_mod for example. Note that there are two ways to generate area: \$area is an ellipsoid based calculation using not just ...
• 10.5k

### Calculate total area of polygons in shapefile using GDAL?

Yes, it is possible, but you need to use the OGR SQLite dialect as follows: ogrinfo -dialect SQLite -sql 'SELECT SUM(ST_Area(geometry))/10000 FROM myshapefile' myshapefile.shp Also, ensure that ...
• 4,902

### Calculating area of polygons without script in QGIS Field calculator

There are two tabs under the field calculator - Expression and Function editor, i suppose you're referring to the function editor tab which requires coding skills. If you stay on the Expression tab ...
• 5,743
Accepted

### Deleting parts of MultiPolygon based on area using PyQGIS

You can make a new part list from the MultiPolygon instead of deleting the parts. layer = iface.activeLayer() # Minimum area threshold minimum_area = 2000 layer.startEditing() # Loop through all ...
• 77.3k

### Calculating area in km² for Polygon in WKT using Python

The other answers seem to be correct, except that at some point, the lat1 and lat2 parameters in the pyproj code were renamed with underscores: lat_1 and lat_2 (see https://stackoverflow.com/a/...
• 203

### Selecting polygon with the largest area in QGIS

You would be better off using "Select by expression" instead of "Select by attribute". Your expression should be something like: "AREA" = maximum("AREA") ...
• 1,986
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### How does \$area function calculate area in QGIS?

Function \$area: Returns the area of the current feature. The area calculated by this function respects both the current project's ellipsoid setting and area unit settings. For example, if an ...
• 14.6k

### Calculating percentage of overlap of two layers in QGIS 3

Using a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer.... Let's assume there are two overlapping polygon layers called 'LayerA' (brown) and 'LayerB' (grey), see ...
• 33.4k
Accepted

### \$area gives NULL for some polygons in QGIS's Field Calculator

Short Answer you have to re-project the shapefile to EPSG:3148 - Indian 1960 / UTM zone 48N Long Answer Load the shapefile Left click the shapefile in Layers pallet Go to Export > Save feature as ...

### Why accurate area of all countries cannot be obtained using a single EPSG code, even if it corresponds to an equal-area projection?

In addition to the fact that EPSG:3395 is not an equal area projection (therefore inaccurate for area measures), as mentioned by @Babel, a precise measure of the area requires a good projection. ...
• 49.8k

### Calculating polygon area in QGIS without adding new field

The identify tool does offer you this information. Click any feature, then expand the topmost dropdown menu. Here all basic geometric information is hidden, incl. the area and circumfence.
• 16.7k

### Calculating polygon area in QGIS without adding new field

Create a label with the expressin \$area (I should have used round(\$area)):
• 75.2k
Accepted

### Calculating polygon area within other polygon using GeoPandas

Use GeoPandas Overlay polygons = gpd.read_file("Polygons.shp") small_polygon = gpd.read_file("Small_polygon.shp") Intersection of the two GeoDataFrames: result = gpd.overlay(...
• 55.2k