Add examples to elucidate the formulas (GH-14898)

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Raymond Hettinger 2019-07-21 16:32:00 -07:00 committed by GitHub
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@ -527,14 +527,18 @@ However, for reading convenience, most of the examples show sorted sequences.
The default *method* is "exclusive" and is used for data sampled from The default *method* is "exclusive" and is used for data sampled from
a population that can have more extreme values than found in the a population that can have more extreme values than found in the
samples. The portion of the population falling below the *i-th* of samples. The portion of the population falling below the *i-th* of
*m* data points is computed as ``i / (m + 1)``. *m* sorted data points is computed as ``i / (m + 1)``. Given nine
sample values, the method sorts them and assigns the following
percentiles: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%.
Setting the *method* to "inclusive" is used for describing population Setting the *method* to "inclusive" is used for describing population
data or for samples that include the extreme points. The minimum data or for samples that are known to include the most extreme values
value in *dist* is treated as the 0th percentile and the maximum from the population. The minimum value in *dist* is treated as the 0th
value is treated as the 100th percentile. The portion of the percentile and the maximum value is treated as the 100th percentile.
population falling below the *i-th* of *m* data points is computed as The portion of the population falling below the *i-th* of *m* sorted
``(i - 1) / (m - 1)``. data points is computed as ``(i - 1) / (m - 1)``. Given 11 sample
values, the method sorts them and assigns the following percentiles:
0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%.
If *dist* is an instance of a class that defines an If *dist* is an instance of a class that defines an
:meth:`~inv_cdf` method, setting *method* has no effect. :meth:`~inv_cdf` method, setting *method* has no effect.