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Basic operations in H3

This article builds on Introduction to H3 and presents basic H3 operations in Python. Although the core library is written in C, there are bindings for many other languages. H3 supports efficient spatial analysis through key functions, such as converting coordinates to indexes, finding neighboring cells, and computing distances.

image of Víctor Centelles
Víctor Centelles
Software Architect
December 4th, 2025

    Lat/Long to H3 index conversion

    This operation converts a specific geographic coordinate (latitude and longitude) into a unique H3 hexagonal index at a specified resolution.

    Function:

    Lat/Long to H3 index conversion 
          
import h3

lat, lng = 37.769377, -122.388903
resolution = 9

h3_idx = h3.latlng_to_cell(lat, lng, resolution)
# h3_idx = h3.geo_to_h3(lat, lng, resolution)  # ► in v3.x

print(h3_idx)

# Output: 89283082e73ffff
    article image

    Lat/Long to H3 index conversion (image from https://clupasq.github.io/h3-viewer/)

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    H3 index to Lat/Long conversion

    The reverse operation converts an H3 index back into the geographic coordinates of the hexagon's center.

    Function:

    snippet.python 
          
import h3

h3_idx = '89283082803ffff'

coordinates = h3.cell_to_latlng(h3_idx)
# coordinates = h3.h3_to_geo(h3_idx)  # ► in v3.x

print(coordinates)

# Output: (37.773515097238146, -122.4182710369247)
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    Finding neighboring hexagons

    You can identify the cells immediately surrounding a specific index using the k_ring function. This is essential for analyzing proximity and spatial smoothing,.

    Function (where k is the ring size; k=1 returns immediate neighbors):

    Finding neighboring hexagons 
          
import h3

h3_idx = '873975442ffffff'

neighbors = h3.grid_disk(h3_idx, k=1)
# neighbors = h3.k_ring(h3_idx, k=1)   # ► in v3.x

print(neighbors)

# Output
# ['873975442ffffff', 
# '873975455ffffff', 
# '873975451ffffff', 
# '87397545cffffff', 
# '873975443ffffff', 
# '873975440ffffff', 
# '873975446ffffff']
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    Neighboring hexagons

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    Determining hexagon hierarchy (parent/children)

    H3 is hierarchical, allowing you to move between resolution levels. You can find the smaller subdivisions ("children") of a hexagon or the larger container ("parent") hexagon.

    Functions:

    Returns the finer hexagons contained within the index.

    Returns the coarser parent index.

    Determining hexagon hierarchy (parent/children) 
          
import h3

h3_idx = '873975442ffffff'

children = h3.cell_to_children(h3_idx)
# neighbors = h3.k_ring(h3_idx, k=1)   # ► in v3.x

print(children)
# Output:
# ['8839754421fffff',
# '8839754423fffff',
# '8839754425fffff',
# '8839754427fffff',
# '8839754429fffff',
# '883975442bfffff',
# '883975442dfffff']

parent = h3.cell_to_parent('8839754421fffff')
# parent = h3.h3_to_parent('8839754421fffff')  # ► in v3.x

print(parent)
# Output: '873975442ffffff'
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    Obtaining the H3 cell area

    This operation calculates the physical area of a specific H3 cell, which defaults to square kilometers (km²).

    Function:

    Obtaining the H3 cell area 
          
import h3

h3_idx = '873975442ffffff'

area = h3.cell_area(h3_idx)

print(area)
# Output: 5.036490172849032

h3.cell_area(h3_idx, 'm^2')
# Output: 5036490.172849031
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    Obtaining H3 cell area (image from https://clupasq.github.io/h3-viewer/)

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    Distance between H3 cells

    H3 allows you to calculate the grid distance between two cells. This is the number of steps required to move from one hexagon to another on the grid.

    Function:

    Distance between H3 cells 
          
import h3

# Neighboring cells 

c1 = '873975473ffffff'
c2 = '873975454ffffff'
c3 = '873975450ffffff'

print(h3.grid_distance(c1, c2)) # Output: 1
print(h3.grid_distance(c2, c3)) # Output: 1
print(h3.grid_distance(c1, c3)) # Output: 2

# print(h3.h3_distance(c1, c2)) # Output: 1   # ► in v3.x
# print(h3.h3_distance(c2, c3)) # Output: 1   # ► in v3.x
# print(h3.h3_distance(c1, c3)) # Output: 2   # ► in v3.x
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    Distance between H3 cells (image from https://clupasq.github.io/h3-viewer/)

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