4.2 Multivariate Local Geary

Multivariate local geary (2019) is a multivariate extension of local geary which measures the extent to which neighbors in multiattribute space are also neighbors in geographical space. For more information, please read: https://geodacenter.github.io/workbook/6c_local_multi/lab6c.html

local_multigeary()

local_multigeary() is a PostgreSQL WINDOW function. Please call it with an OVER clause.

Synopsis

Short version:

float[] local_multigeary(anyarray vals,  bytea weights)

Full version:

float[] local_multigeary(anyarray vals,  bytea weights,
    integer permutations, 
    character varying permutation_method,
    float significance_cutoff, 
    integer cpu_threads, 
    integer seed)

Arguments

Name	Type	Description
vals	anyarray	an array of the numeric columns that contains the values for LISA statistics
weights	bytea	a bytea column that stores the spatial weights information
permutations	integer	the number of permutations for the LISA computation. Default: 999.
permutation_method	character varying	The permutation method used for the LISA computation. Options are 'complete', 'lookup'. Default: 'lookup'.
significance_cutoff	float	the cutoff value for significance p-values to filter not-significant clusters. Default: 0.05.
cpu_threads	integer	the number of cpu threads used for parallel LISA computation. Default: 6.
seed	integer	the seed for random number generator used in LISA statistics. Default: 123456789.

Return

Type	Description
float[]	an array contains 3 values, which are {'lisa value', 'pseudo-p value' and 'cluster indicator'}

Cluster Indicators

The predefined values of the cluster indicators of multivariate local moran are:

Cluster indicator value	Description	Color
0	Not significant	#eeeeee
1	Positive	#b2182b
2	Negative	#67adc7
3	Undefined Value	#464646
4	Isolated	#999999

Examples

Apply local multivariate geary statistics on the variable ["hr60", "ue60", "dv60"] (homicide, unemployment, divorce rate 1960 in natregimes dataset)using queen contiguity weights "queen_w":

Please see chapter 'Contiguity Based Weights' for how to create a Queen contiguity weights.

SELECT local_multigeary(ARRAY[hr60, ue60, dv60], queen_w) OVER() FROM natregimes;

       local_multigeary        
-------------------------------
 {0.143230008312297,0.001,1}
 {0.870354875283013,0.001,1}
 {0.463879925600245,0.053,0}
 ...