getis_ord
Getis Ord functions. From the 1992 paper by Getis & Ord.
Getis, A., & Ord, J. K. (1992). The analysis of spatial association by use of distance statistics. Geographical Analysis, 24(3), 189-206. https://doi.org/10.1111/j.1538-4632.1992.tb00261.x
g_local(dataframe, x, weights='weights', permutations=0, star=False, island_weight=0.0)
Performs the Gi or Gi* statistic on the x column of the dataframe.
Weights should be the neighbors of this row. The members of the weights should be comprised of structs containing a
value column and a neighbor column. The neighbor column should be the contents of the neighbors with the same types
as the parent row (minus neighbors). You can use wherobots.weighing.add_distance_band_column
to achieve this. To
calculate the Gi* statistic, ensure the focal observation is in the neighbors array (i.e. the row is in the weights
column) and star=true
. Significance is calculated with a z score. Permutation tests are not yet implemented and
thus island weight does nothing. The following columns will be added: G, E[G], V[G], Z, P.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
dataframe
|
DataFrame
|
the dataframe to perform the G statistic on |
required |
x
|
str
|
The column name we want to perform hotspot analysis on |
required |
weights
|
str
|
The column name containing the neighbors array. The neighbor column should be the contents of
the neighbors with the same types as the parent row (minus neighbors). You can use
|
'weights'
|
permutations
|
int
|
Not used. Permutation tests are not supported yet. The number of permutations to use for the significance test. |
0
|
star
|
bool
|
Whether the focal observation is in the neighbors array. If true this calculates Gi*, otherwise Gi |
False
|
island_weight
|
float
|
Not used. The weight for the simulated neighbor used for records without a neighbor in perm tests |
0.0
|
Returns: A dataframe with the original columns plus the columns G, E[G], V[G], Z, P.