Miscellaneous Functions

Utility functions for resolution selection and grid statistics.

findResolutionByCLS

Find the resolution whose Characteristic Length Scale (CLS) is closest to a target diameter in metres.

findResolutionByCLS(target_m, prefer?) → int

Parameter	Type	Description
target_m	float	Target cell diameter in metres
prefer	"closest" | "finer" | "coarser"	Strategy when target falls between levels

Python — dggrid4py

dggrid4py has no dedicated lookup function. Use the resolution table from the experimental igeo7_ext module (dggrid as in the API Overview):

from dggrid4py import igeo7_ext

# resolution table, indexed by resolution; ISEA7H has the same cells as IGEO7
stats = igeo7_ext.dggrid_get_res(dggrid, "ISEA7H", 20)

# Find resolution closest to 1 km cell diameter
res = (stats["cls_m"] - 1000).abs().idxmin()
print(res)   # 9  (CLS = 1268.6 m)

# Find resolution closest to 10 m cell diameter
res = (stats["cls_m"] - 10).abs().idxmin()
print(res)   # 14  (CLS = 9.8 m)

Julia — IGEO7.jl

using IGEO7

find_resolution_by_cls_m(1000)                          # 9
find_resolution_by_cls_m(10.0, prefer=:larger)          # 14
find_resolution_by_cls_m(10.0, prefer=:smaller)         # 15

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findResolutionByArea

Find the resolution whose cell area is closest to a target area in m².

findResolutionByArea(target_m2, prefer?) → int

Python

# Resolution closest to 1 km² cell area (stats table as above)
res = (stats["average_hexagon_area_m2"] - 1e6).abs().idxmin()
print(res)   # 9  (area = 1,263,990 m²)

Julia

find_resolution_by_area_m2(1e6)   # 9

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getResolutionStats

Get the precomputed statistics for a single resolution level.

getResolutionStats(resolution) → {num_cells, area_km2, area_m2, cls_km, cls_m}

Python

# One row of the stats table (as above)
print(stats.loc[9].to_dict())
# {'cells': 403536072.0, 'average_hexagon_area_km2': 1.2639902, 'cls_km': 1.2686064,
#  'average_hexagon_area_m2': 1263990.25, 'cls_m': 1268.6064}

Julia

using IGEO7

s = get_resolution_stats(9)
s.num_cells   # 403536072
s.area_m2     # 1263990.2
s.cls_m       # 1268.6064

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gridStatsTable

Generate the full statistics table for all resolutions of a DGGS type.

gridStatsTable(dggs_type, max_resolution) → DataFrame

Python — dggrid4py

df = dggrid.grid_stats_table("IGEO7", 20)
print(df.to_string())

This calls DGGRID directly and returns the authoritative values for all 21 resolution levels. The Resolution Table in this documentation is derived from this output.

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Resolution Stats Reference

The full precomputed table from IGEO7.jl:

Res	Cells	Area (m²)	CLS (m)
0	12	51,006,562,172,408.9	8,199,500.4
1	72	7,286,651,738,915.6	3,053,223.2
2	492	1,040,950,248,416.5	1,151,643.0
3	3,432	148,707,178,345.2	435,153.1
4	24,012	21,243,882,620.7	164,465.6
5	168,072	3,034,840,374.4	62,161.8
6	1,176,492	433,548,624.9	23,494.9
7	8,235,432	61,935,517.8	8,880.2
8	57,648,012	8,847,931.1	3,356.4
9	403,536,072	1,263,990.2	1,268.6
10	2,824,752,492	180,570.0	479.5
11	19,773,267,432	25,795.7	181.2
12	138,412,872,012	3,685.1	68.5
13	968,890,104,072	526.4	25.9
14	6,782,230,728,492	75.2	9.8
15	47,475,615,099,432	10.7	3.7
16	332,329,305,696,012	1.5	1.4
17	2,326,305,139,872,072	0.2	0.528

See Resolution Table for the full table including resolutions 18–20.