18 gars

Working with GARS in Vgrid DGGS¶

Full Vgrid DGGS documentation is available at vgrid document.

To work with Vgrid DGGS directly in GeoPandas and Pandas, please use vgridpandas. Full Vgridpandas DGGS documentation is available at vgridpandas document.

To work with Vgrid DGGS in QGIS, install the Vgrid Plugin.

To visualize DGGS in Maplibre GL JS, try the vgrid-maplibre library.

For an interactive demo, visit the Vgrid Homepage.

Install vgrid¶

Uncomment the following line to install vgrid.

In [1]:

# %pip install vgrid --upgrade

# %pip install vgrid --upgrade

latlon2gars¶

In [2]:

from vgrid.conversion.latlon2dggs import latlon2gars

lat = 10.775276
lon = 106.706797
res = 3
gars_id = latlon2gars(lat, lon, res)
gars_id

from vgrid.conversion.latlon2dggs import latlon2gars lat = 10.775276 lon = 106.706797 res = 3 gars_id = latlon2gars(lat, lon, res) gars_id

Out[2]:

'574JK19'

GARS to Polygon¶

In [3]:

from vgrid.conversion.dggs2geo.gars2geo import gars2geo

gars_geo = gars2geo(gars_id)
gars_geo

from vgrid.conversion.dggs2geo.gars2geo import gars2geo gars_geo = gars2geo(gars_id) gars_geo

Out[3]:

GARS to GeoJSON¶

In [ ]:

from vgrid.conversion.dggs2geo.gars2geo import gars2geojson

gars_geojson = gars2geojson(gars_id)
# gars_geojson

from vgrid.conversion.dggs2geo.gars2geo import gars2geojson gars_geojson = gars2geojson(gars_id) # gars_geojson

GARS Generator¶

In [1]:

from vgrid.generator.garsgrid import garsgrid

gars_grid = garsgrid(
    resolution=4,
    bbox=[106.50410038, 10.68281767, 106.88230310, 10.82281670],
    output_format="geoparquet",
)
# gars_grid.plot(edgecolor="white")

from vgrid.generator.garsgrid import garsgrid gars_grid = garsgrid( resolution=4, bbox=[106.50410038, 10.68281767, 106.88230310, 10.82281670], output_format="geoparquet", ) # gars_grid.plot(edgecolor="white")

Generating GARS DGGS: 100%|██████████| 207/207 [00:00<00:00, 4712.42 cells/s]

Output file saved as: d:\Github\vgrid\docs\notebooks\gars_grid_4.parquet

GARS Inspect¶

In [1]:

from vgrid.stats.garsstats import garsinspect

resolution = 1
gars_inspect = garsinspect(resolution)
gars_inspect.head()

from vgrid.stats.garsstats import garsinspect resolution = 1 gars_inspect = garsinspect(resolution) gars_inspect.head()

Generating GARS DGGS: 100%|██████████| 259200/259200 [00:29<00:00, 8664.08 cells/s] 

Out[1]:

	gars	resolution	center_lat	center_lon	cell_width	cell_height	cell_area	cell_perimeter	geometry	crossed	norm_area	ipq	zsc	cvh
0	001AA	1	-89.75	-179.75	0.000000	55846.975448	1.360844e+07	112181.299964	POLYGON ((-179.5 -90, -179.5 -89.5, -180 -89.5...	False	0.006915	0.013589	0.116571	1.0
1	001AB	1	-89.25	-179.75	487.349067	55846.889466	4.082421e+07	113155.788271	POLYGON ((-179.5 -89.5, -179.5 -89, -180 -89, ...	False	0.020746	0.040066	0.200164	1.0
2	001AC	1	-88.75	-179.75	974.660272	55846.717528	6.803661e+07	114129.991081	POLYGON ((-179.5 -89, -179.5 -88.5, -180 -88.5...	False	0.034574	0.065638	0.256198	1.0
3	001AD	1	-88.25	-179.75	1461.895753	55846.459688	9.524342e+07	115103.832790	POLYGON ((-179.5 -88.5, -179.5 -88, -180 -88, ...	False	0.048400	0.090337	0.300561	1.0
4	001AE	1	-87.75	-179.75	1949.017659	55846.116027	1.224424e+08	116077.237862	POLYGON ((-179.5 -88, -179.5 -87.5, -180 -87.5...	False	0.062222	0.114195	0.337928	1.0

GARS Normalized Area Histogram¶

In [2]:

from vgrid.stats.garsstats import gars_norm_area_hist

gars_norm_area_hist(gars_inspect)

from vgrid.stats.garsstats import gars_norm_area_hist gars_norm_area_hist(gars_inspect)

Distribution of GARS Area Distortions¶

In [3]:

from vgrid.stats.garsstats import gars_norm_area

gars_norm_area(gars_inspect)

from vgrid.stats.garsstats import gars_norm_area gars_norm_area(gars_inspect)

GARS IPQ Compactness Histogram¶

Isoperimetric Inequality (IPQ) Compactness (suggested by Osserman, 1978):

$$C_{IPQ} = \frac{4 \pi A}{p^2}$$ The range of the IPQ compactness metric is [0,1].

A circle represents the maximum compactness with a value of 1.

As shapes become more irregular or elongated, their compactness decreases toward 0.

In [4]:

from vgrid.stats.garsstats import gars_compactness_ipq_hist

gars_compactness_ipq_hist(gars_inspect)

from vgrid.stats.garsstats import gars_compactness_ipq_hist gars_compactness_ipq_hist(gars_inspect)

Distribution of GARS IPQ Compactness¶

In [5]:

from vgrid.stats.garsstats import gars_compactness_ipq

gars_compactness_ipq(gars_inspect)

from vgrid.stats.garsstats import gars_compactness_ipq gars_compactness_ipq(gars_inspect)

GARS Convex hull Compactness Histogram:¶

$$C_{CVH} = \frac{A}{A_{CVH}}$$

The range of the convex hull compactness metric is [0,1].

As shapes become more concave, their convex hull compactness decreases toward 0.

In [6]:

from vgrid.stats.garsstats import gars_compactness_cvh_hist

gars_compactness_cvh_hist(gars_inspect)

from vgrid.stats.garsstats import gars_compactness_cvh_hist gars_compactness_cvh_hist(gars_inspect)

Distribution of GARS Convex hull Compactness¶

In [7]:

from vgrid.stats.garsstats import gars_compactness_cvh

gars_compactness_cvh(gars_inspect)

from vgrid.stats.garsstats import gars_compactness_cvh gars_compactness_cvh(gars_inspect)

GARS Statistics¶

Characteristic Length Scale (CLS - suggested by Ralph Kahn): the diameter of a spherical cap of the same cell's area

In [11]:

from vgrid.stats import garsstats

garsstats("km")

from vgrid.stats import garsstats garsstats("km")

Out[11]:

	resolution	number_of_cells	avg_edge_len_km	avg_cell_area_km2	cls_km
0	1	259200	44.360408	1967.845763	50.055392
1	2	1036800	22.180204	491.961441	25.027684
2	3	9331200	7.393401	54.662382	8.342560
3	4	233280000	1.478680	2.186495	1.668512