get_disparity_min_metric squashes any score_threshold configuration in groups model

[thcrock]

If multiple 'score_thresholds' are configured in group crosstabs, they get squashed if passed to 'get_disparity_min_metric'.

from aequitas.preprocessing import preprocess_input_df
from aequitas.bias import Bias
from aequitas.group import Group
import pandas as pd

protected_df = pd.read_csv('compas_for_aequitas.csv')
g = Group()
score_thresholds = {'rank_abs': [25], 'rank_pct': [50]}
df, attr_cols = preprocess_input_df(protected_df)
groups_model, attr_cols = g.get_crosstabs(df, score_thresholds=score_thresholds, model_id=45, attr_cols=attr_cols)
bias = Bias()
bias_df = bias.get_disparity_min_metric(groups_model, df)
bias_df

The bias_df in this case does end up with more rows than if we were to only give it one score threshold, but they all have the same resulting score_threshold and k values.

This problem does not seem to apply to get_disparity_major_group.