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+# -*- coding:utf-8 -*-
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+"""
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+@author: yq
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+@time: 2024/1/2
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+@desc: iv值及单调性筛选类
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+"""
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+from itertools import combinations_with_replacement
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+from typing import List
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+
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+import numpy as np
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+import pandas as pd
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+
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+from entitys import DataSplitEntity, CandidateFeatureEntity, DataProcessConfigEntity
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+from .feature_utils import f_judge_monto
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+from .filter_strategy_base import FilterStrategyBase
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+
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+
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+class StrategyIv(FilterStrategyBase):
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+
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+ def __init__(self, *args, **kwargs):
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+ super().__init__(*args, **kwargs)
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+
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+ def _f_get_best_bins(self, data: DataSplitEntity, x_column: str):
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+ # 贪婪搜索【训练集】及【测试集】加起来【iv】值最高的且【单调】的分箱
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+ interval = self.data_process_config.bin_search_interval
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+ iv_threshold = self.data_process_config.iv_threshold
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+ special_values = self.data_process_config.get_special_values(x_column)
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+ y_column = self.data_process_config.y_column
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+
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+ def _n0(x):
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+ return sum(x == 0)
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+
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+ def _n1(x):
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+ return sum(x == 1)
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+
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+ def _f_distribute_balls(balls, boxes):
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+ # 计算在 balls - 1 个空位中放入 boxes - 1 个隔板的方法数
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+ total_ways = combinations_with_replacement(range(balls + boxes - 1), boxes - 1)
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+ distribute_list = []
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+ # 遍历所有可能的隔板位置
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+ for combo in total_ways:
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+ # 根据隔板位置分配球
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+ distribution = [0] * boxes
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+ start = 0
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+ for i, divider in enumerate(combo):
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+ distribution[i] = divider - start + 1
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+ start = divider + 1
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+ distribution[-1] = balls - start # 最后一个箱子的球数
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+ # 确保每个箱子至少有一个球
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+ if all(x > 0 for x in distribution):
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+ distribute_list.append(distribution)
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+ return distribute_list
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+
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+ def _get_sv_bins(df, x_column, y_column, special_values):
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+ # special_values_bins
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+ sv_bin_list = []
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+ for special in special_values:
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+ dtm = df[df[x_column] == special]
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+ if len(dtm) != 0:
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+ dtm['bin'] = [str(special)] * len(dtm)
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+ binning = dtm.groupby(['bin'], group_keys=False)[y_column].agg(
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+ [_n0, _n1]).reset_index().rename(columns={'_n0': 'good', '_n1': 'bad'})
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+ binning['is_special_values'] = [True] * len(binning)
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+ sv_bin_list.append(binning)
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+ return sv_bin_list
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+
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+ def _get_bins(df, x_column, y_column, breaks_list):
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+ dtm = pd.DataFrame({'y': df[y_column], 'value': df[x_column]})
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+ bstbrks = [-np.inf] + breaks_list + [np.inf]
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+ labels = ['[{},{})'.format(bstbrks[i], bstbrks[i + 1]) for i in range(len(bstbrks) - 1)]
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+ dtm.loc[:, 'bin'] = pd.cut(dtm['value'], bstbrks, right=False, labels=labels)
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+ dtm['bin'] = dtm['bin'].astype(str)
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+ bins = dtm.groupby(['bin'], group_keys=False)['y'].agg([_n0, _n1]) \
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+ .reset_index().rename(columns={'_n0': 'good', '_n1': 'bad'})
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+ bins['is_special_values'] = [False] * len(bins)
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+ return bins
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+
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+ def _calculation_iv(bins):
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+ bins['count'] = bins['good'] + bins['bad']
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+ bins['badprob'] = bins['bad'] / bins['count']
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+ # 单调性判断
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+ bad_prob = bins[bins['is_special_values'] == False]['badprob'].values.tolist()
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+ if not f_judge_monto(bad_prob):
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+ return -1
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+ # 计算iv
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+ infovalue = pd.DataFrame({'good': bins['good'], 'bad': bins['bad']}) \
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+ .replace(0, 0.9) \
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+ .assign(
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+ DistrBad=lambda x: x.bad / sum(x.bad),
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+ DistrGood=lambda x: x.good / sum(x.good)
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+ ) \
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+ .assign(iv=lambda x: (x.DistrBad - x.DistrGood) * np.log(x.DistrBad / x.DistrGood)) \
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+ .iv
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+ bins['bin_iv'] = infovalue
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+ bins['total_iv'] = bins['bin_iv'].sum()
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+ iv = bins['total_iv'].values[0]
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+ return iv
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+
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+ train_data = data.train_data
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+ train_data_filter = train_data[~train_data[x_column].isin(special_values)]
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+ train_data_filter = train_data_filter.sort_values(by=x_column, ascending=True)
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+ train_data_x = train_data_filter[x_column]
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+
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+ test_data = data.test_data
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+ test_data_filter = None
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+ if test_data is not None and len(test_data) != 0:
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+ test_data_filter = test_data[~test_data[x_column].isin(special_values)]
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+ test_data_filter = test_data_filter.sort_values(by=x_column, ascending=True)
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+
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+ # 构造数据切分点
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+ # 计算 2 - 5 箱的情况
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+ distribute_list = []
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+ points_list = []
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+ for bin_num in list(range(2, 6)):
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+ distribute_list.extend(_f_distribute_balls(int(1 / interval), bin_num))
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+ for distribute in distribute_list:
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+ point_list_cache = []
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+ point_percentile_list = [sum(distribute[0:idx + 1]) * interval for idx, _ in enumerate(distribute[0:-1])]
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+ for point_percentile in point_percentile_list:
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+ point = train_data_x.iloc[int(len(train_data_x) * point_percentile)]
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+ if point not in point_list_cache:
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+ point_list_cache.append(point)
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+ if point_list_cache not in points_list:
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+ points_list.append(point_list_cache)
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+ # IV与单调性过滤
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+ iv_max = 0
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+ breaks_list = []
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+ train_sv_bin_list = _get_sv_bins(train_data, x_column, y_column, special_values)
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+ test_sv_bin_list = None
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+ if test_data_filter is not None:
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+ test_sv_bin_list = _get_sv_bins(test_data, x_column, y_column, special_values)
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+ from tqdm import tqdm
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+ for point_list in tqdm(points_list):
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+ train_bins = _get_bins(train_data_filter, x_column, y_column, point_list)
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+ # 与special_values合并计算iv
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+ for sv_bin in train_sv_bin_list:
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+ train_bins = pd.concat((train_bins, sv_bin))
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+ train_iv = _calculation_iv(train_bins)
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+ # 只限制训练集的单调性与iv值大小
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+ if train_iv < iv_threshold:
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+ continue
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+
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+ test_iv = 0
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+ if test_data_filter is not None:
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+ test_bins = _get_bins(test_data_filter, x_column, y_column, point_list)
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+ for sv_bin in test_sv_bin_list:
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+ test_bins = pd.concat((test_bins, sv_bin))
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+ test_iv = _calculation_iv(test_bins)
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+
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+ iv = train_iv + test_iv
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+ if iv > iv_max:
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+ iv_max = iv
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+ breaks_list = point_list
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+
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+ return iv_max, breaks_list
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+
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+ def filter(self, data: DataSplitEntity, *args, **kwargs):
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+ x_columns_candidate = self.data_process_config.x_columns_candidate
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+ candidate_num = self.data_process_config.candidate_num
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+ candidate_list: List[CandidateFeatureEntity] = []
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+ for x_column in x_columns_candidate:
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+ iv_max, breaks_list = self._f_get_best_bins(data, x_column)
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+ candidate_list.append(CandidateFeatureEntity(x_column, breaks_list, iv_max))
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+ candidate_list.sort(key=lambda x: x.iv_max, reverse=True)
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+
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+ return candidate_list[0:candidate_num]
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