4 Map Classification

pygeoda provids following methods for univariate map classification:

  • Hinge box breaks: hinge15_breaks() and hinge30_breaks()

  • Natural breaks: natural_breaks()

  • Quantile breaks: quantile_breaks()

  • Percentile breaks: percentile_breaks()

  • Standard deviation breaks: stddev_breaks()

These methods of map classification calculate a corresponding breakpoint list for a selected variable. For more information about the map classification, please read Dr. Luc Anselin’s lab note: http://geodacenter.github.io/workbook/6a_local_auto/lab6a.html.

4.1 Hinge Box Breaks

Hinge Box Breaks calculates a list of breakpoints, including the top, bottom, median, and two quartiles of the data. Here the hinge can be 1.5 or 3.0. For example, we can call function hinge15_breaks() or hinge30_breaks with the data “Crm_prp” as input parameter:

>>> breaks15 = pygeoda.hinge15_breaks(guerry['Crm_prp'])
>>> print(breaks15)
(1190.0, 5990.0, 7624.0, 9190.0, 13990.0)

>>> breaks30 = pygeoda.hinge30_breaks(guerry['Crm_prp'])
>>> print(breaks30)
(-3610.0, 5990.0, 7624.0, 9190.0, 18790.0)

4.2 Natural Breaks

Natural Breaks calculates a list of breakpoints based on the fracture principle of maximum similarity within a group. For example, we can call function natural_breaks() with the data “Crm_prp” and the number of classification “k” as input parameters:

>>> breaks = pygeoda.natural_breaks(5, guerry['Crm_prp'])
>>> print(breaks)
(5521.0, 7204.0, 10237.0, 15890.0)

4.3 Quantile Breaks

Quantile Breaks is based on sorted values for a variable that are then grouped into bins that each have the same number of observations, the so-called quantiles. For example, we can call function quantile_breaks() with the data “Crm_prp”, and the number of classification “k” as input parameters:

>>> breaks = pygeoda.quantile_breaks(5, guerry['Crm_prp'])
>>> print(breaks)
(5439.0, 6886.0, 8205.0, 9584.5)

4.4 Percentile Breaks

Percentile Breaks divides the data into six ranges: the lowest 1%, 1-10%, 10-50%, 50-90%, 90-99% and the top 1%. It returns the range boundaries as a breakpoint list. For example, we can call function natural_breaks() with the data “Crm_prp” as input parameter:

>>> breaks = pygeoda.percentile_breaks(guerry['Crm_prp'])
>>> print(breaks)
(1906.3, 4529.0, 7624.0, 10954.0, 19467.8)

4.5 Standard Deviation Breaks

Standard Deviation Breaks calculates the number of standard deviational units of the range from lowest to highest, returning a breakpoint list. For example, we can call function stddev_breaks() with the data “Crm_prp” as input parameter:

>>> breaks = pygeoda.stddev_breaks(guerry['Crm_prp'])
>>> print(breaks)
(1784.1106064421238, 4832.725891456355, 7881.341176470588, 10929.95646148482, 13978.571746499052)