# `skcriteria.utils.rank` module¶

Functions for calculate and compare ranks (ordinal series).

skcriteria.utils.rank.rank_values(arr, reverse=False)[source]

Evaluate an array and return a 1 based ranking.

Parameters
• arr ((`numpy.ndarray`, `numpy.ndarray`)) – A array with values

• reverse (`bool` default False) – By default (False) the lesser values are ranked first (like in time lapse in a race or Golf scoring) if is True the data is highest values are the first.

Returns

Array of rankings the i-nth element has the ranking of the i-nth element of the row array.

Return type

`numpy.ndarray`

Examples

```>>> from skcriteria.util.rank import rank_values
>>> # the fastest (the lowest value) goes first
>>> time_laps = [0.59, 1.2, 0.3]
>>> rank_values(time_laps)
array([2, 3, 1])
>>> # highest is better
>>> scores = [140, 200, 98]
>>> rank_values(scores, reverse=True)
array([2, 1, 3])
```
skcriteria.utils.rank.dominance(array_a, array_b, reverse=False)[source]

Calculate the dominance or general dominance between two arrays.

Parameters
• array_a – The first array to compare.

• array_b – The second array to compare.

• reverse (bool (default=False)) – array_a[i] ≻ array_b[i] if array_a[i] > array_b[i] if reverse is False, otherwise array_a[i] ≻ array_b[i] if array_a[i] < array_b[i]. Also revese can be an array of boolean of the same shape as array_a and array_b to revert every item independently. In other words, reverse assume the data is a minimization problem.

Returns

dominance – Named tuple with 4 parameters:

• eq: How many values are equals in both arrays.

• aDb: How many values of array_a dominate those of the same

position in array_b.

• bDa: How many values of array_b dominate those of the same

position in array_a.

• eq_where: Where the values of array_a are equals those of the same

position in array_b.

• aDb_where: Where the values of array_a dominates those of the same

position in array_b.

• bDa_where: Where the values of array_b dominates those of the same

position in array_a.

Return type

_Dominance