# pysal.explore.giddy.mobility.markov_mobility¶

pysal.explore.giddy.mobility.markov_mobility(p, measure='P', ini=None)[source]

Markov-based mobility index.

Parameters: p : array (k, k), Markov transition probability matrix. measure : string If measure= “P”, $$M_{P} = \frac{m-\sum_{i=1}^m P_{ii}}{m-1}$$; if measure = “D”, $$M_{D} = 1 - |\det(P)|$$, where $$\det(P)$$ is the determinant of $$P$$; if measure = “L2”, $$M_{L2} = 1 - |\lambda_2|$$, where $$\lambda_2$$ is the second largest eigenvalue of $$P$$; if measure = “B1”, $$M_{B1} = \frac{m-m \sum_{i=1}^m \pi_i P_{ii}}{m-1}$$, where $$\pi$$ is the initial income distribution; if measure == “B2”, $$M_{B2} = \frac{1}{m-1} \sum_{i=1}^m \sum_{ j=1}^m \pi_i P_{ij} |i-j|$$, where $$\pi$$ is the initial income distribution. ini : array (k,), initial distribution. Need to be specified if measure = “B1” or “B2”. If not, the initial distribution would be treated as a uniform distribution. mobi : float Mobility value.

Notes

The mobility indices are based on [FSZ04].

Examples

>>> import numpy as np
>>> import pysal.lib
>>> import pysal.viz.mapclassify as mc
>>> from pysal.explore.giddy.markov import Markov
>>> from pysal.explore.giddy.mobility import markov_mobility
>>> f = pysal.lib.io.open(pysal.lib.examples.get_path("usjoin.csv"))
>>> pci = np.array([f.by_col[str(y)] for y in range(1929,2010)])
>>> q5 = np.array([mc.Quantiles(y).yb for y in pci]).transpose()
>>> m = Markov(q5)
>>> m.p
array([[0.91011236, 0.0886392 , 0.00124844, 0.        , 0.        ],
[0.09972299, 0.78531856, 0.11080332, 0.00415512, 0.        ],
[0.        , 0.10125   , 0.78875   , 0.1075    , 0.0025    ],
[0.        , 0.00417827, 0.11977716, 0.79805014, 0.07799443],
[0.        , 0.        , 0.00125156, 0.07133917, 0.92740926]])

1. Estimate Shorrock1 mobility index:
>>> mobi_1 = markov_mobility(m.p, measure="P")
>>> print("{:.5f}".format(mobi_1))
0.19759

1. Estimate Shorrock2 mobility index:
>>> mobi_2 = markov_mobility(m.p, measure="D")
>>> print("{:.5f}".format(mobi_2))
0.60685

1. Estimate Sommers and Conlisk mobility index:
>>> mobi_3 = markov_mobility(m.p, measure="L2")
>>> print("{:.5f}".format(mobi_3))
0.03978


(4) Estimate Bartholomew1 mobility index (note that the initial distribution should be given):

>>> ini = np.array([0.1,0.2,0.2,0.4,0.1])
>>> mobi_4 = markov_mobility(m.p, measure = "B1", ini=ini)
>>> print("{:.5f}".format(mobi_4))
0.22777


(5) Estimate Bartholomew2 mobility index (note that the initial distribution should be given):

>>> ini = np.array([0.1,0.2,0.2,0.4,0.1])
>>> mobi_5 = markov_mobility(m.p, measure = "B2", ini=ini)
>>> print("{:.5f}".format(mobi_5))
0.04637