esda.Moran_Local_BV

class esda.Moran_Local_BV(x, y, w, transformation='r', permutations=999, geoda_quads=False, n_jobs=1, keep_simulations=True, seed=None, island_weight=0)[source]

Bivariate Local Moran Statistics.

Parameters:
wW | Graph

spatial weights instance as W or Graph aligned with y

transformation{‘R’, ‘B’, ‘D’, ‘U’, ‘V’}

weights transformation, default is row-standardized “r”. Other options include “B”: binary, “D”: doubly-standardized, “U”: untransformed (general weights), “V”: variance-stabilizing.

p_values

If True use GeoDa scheme: HH=1, LL=2, LH=3, HL=4 If False use PySAL Scheme: HH=1, LH=2, LL=3, HL=4

keep_simulationsBoolean

(default=True) If True, the entire matrix of replications under the null is stored in memory and accessible; otherwise, replications are not saved

seedNone/int

Seed to ensure reproducibility of conditional randomizations. Must be set here, and not outside of the function, since numba does not correctly interpret external seeds nor numpy.random.RandomState instances.

island_weight:

value to use as a weight for the “fake” neighbor for every island. If numpy.nan, will propagate to the final local statistic depending on the stat_func. If 0, then the lag is always zero for islands.

Attributes:
wW | Graph

original w object

values indicate quandrant location 1 HH, 2 LH, 3 LL, 4 HL

p-value based on permutations (one-sided) null: spatial randomness alternative: the observed Ii is further away or extreme from the median of simulated values. It is either extremelyi high or extremely low in the distribution of simulated Is.

average values of local Is from permutations

variance of Is from permutations

seI_sim: array

(if permutations>0) standard deviations of Is under permutations.

z_simarrray

(if permutations>0) standardized Is based on permutations

p_z_sim: array

(if permutations>0) p-values based on standard normal approximation from permutations (one-sided) for two-sided tests, these values should be multiplied by 2

Examples

>>> import libpysal
>>> import numpy as np
>>> np.random.seed(10)
>>> w = libpysal.io.open(libpysal.examples.get_path("sids2.gal")).read()
>>> f = libpysal.io.open(libpysal.examples.get_path("sids2.dbf"))
>>> x = np.array(f.by_col['SIDR79'])
>>> y = np.array(f.by_col['SIDR74'])
>>> from esda.moran import Moran_Local_BV
>>> lm =Moran_Local_BV(x, y, w, transformation = "r",                                permutations = 99)
>>> lm.q[:10]
array([3, 4, 3, 4, 2, 1, 4, 4, 2, 4])
>>> lm = Moran_Local_BV(x, y, w, transformation = "r",                                permutations = 99, geoda_quads=True)
>>> lm.q[:10]
array([2, 4, 2, 4, 3, 1, 4, 4, 3, 4])

Note random components result is slightly different values across architectures so the results have been removed from doctests and will be moved into unittests that are conditional on architectures.

__init__(x, y, w, transformation='r', permutations=999, geoda_quads=False, n_jobs=1, keep_simulations=True, seed=None, island_weight=0)[source]

Methods

__init__(x, y, w[, transformation, ...])

by_col(df, x[, y, w, inplace, pvalue, outvals])

Function to compute a Moran_Local_BV statistic on a dataframe

classmethod by_col(df, x, y=None, w=None, inplace=False, pvalue='sim', outvals=None, **stat_kws)[source]

Function to compute a Moran_Local_BV statistic on a dataframe

Parameters:
the bivariate statistic. If no Y is provided, pairwise comparisons among these variates are used instead.

the bivariate statistic. if no Y is provided, pariwise comparisons among the X variates are used instead.

wW | Graph

spatial weights instance as W or Graph aligned with the dataframe. If not provided, this is searched for in the dataframe’s metadata

return a series contaning the results of the computation. If operating inplace, the derived columns will be named ‘column_moran_local_bv’

the Moran_Local_BV statistic’s documentation for available p-values

Moran_Local_BV statistic

documentation for the Moran_Local_BV statistic.

Returns:
the relevant columns attached.