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初赛：

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】1 数据分析及可视化

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】2 问题一 Baseline 和数据

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】3 问题二 思路和python实现
  【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】4 问题三 思路和数据及参考资料

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】5 完整方案和40页论文PDF下载

复赛：

• 【Mathorcup杯大数据挑战赛复赛 B题 二手车估价】思路及Python实现

下载链接

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A】二手车估价问题的数据分析及可视化 代码下载

• [【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】问题一 Baseline 和数据 下载

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】问题二 思路和python实现代码 下载

• [【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】问题三 思路和数据及参考资料 下载

• 【2021 年 MathorCup 高校数学建模挑战赛—赛道A二手车估价问题】5 完整方案和40页论文PDF下载

https://github.com/BetterBench/BetterBench-Shop

1 导入包

import datetime
import numpy as np
import pandas as pd
import numpy as np
from tqdm import tqdm
tqdm.pandas()

读取数据

file1.csv、file2.csv由“附件1：估价训练数据.txt”和“附件2：估价验证数据.txt”格式转换而来

train = pd.read_table('file1.csv',sep='\\t',)
test = pd.read_table('file2.csv',sep='\\t',)

2 特征工程

只使用缺失值较少或者没有的字段

column_tra = ["carid", "tradeTime", "brand", "serial", "model", "mileage", "color", "cityId", "carCode", "transferCount", "seatings", "registerDate",
              "licenseDate", "country", "maketype", "modelyear", "displacement", "gearbox", "oiltype", "newprice", "anonymousFeature1", "anonymousFeature2",
              "anonymousFeature3", "anonymousFeature5", "anonymousFeature6", "anonymousFeature11", "anonymousFeature12", "anonymousFeature14", "price"]
column_te = ["carid", "tradeTime", "brand", "serial", "model", "mileage", "color", "cityId", "carCode", "transferCount", "seatings", "registerDate",
             "licenseDate", "country", "maketype", "modelyear", "displacement", "gearbox", "oiltype", "newprice", "anonymousFeature1", "anonymousFeature2",
             "anonymousFeature3",  "anonymousFeature5", "anonymousFeature6", 
              "anonymousFeature11", "anonymousFeature12", "anonymousFeature14"]

train = train[column_tra]
test = test[column_te]

2.1 缺失值处理

对于分类特征，填充众数

数据不完整

以下每个特征的众数我用字母替代，众数可以自己统计，或者下载完整代码

# 以下分类特征全部填充众数
train['carCode'] = train['carCode'].fillna(a)
train['modelyear'] = train['modelyear'].fillna(b)
train['country'] = train['country'].fillna(c)
train['maketype'] = train['maketype'].fillna(d)
train['gearbox'] = train['gearbox'].fillna(e)
train['anonymousFeature5'] = train['anonymousFeature5'].fillna(f)

test['carCode'] = test['carCode'].fillna(a)
test['modelyear'] = test['modelyear'].fillna(b)
test['country'] = test['country'].fillna(c)
test['maketype'] = test['maketype'].fillna(d)
test['gearbox'] = test['gearbox'].fillna(e)
test['anonymousFeature5'] = test['anonymousFeature5'].fillna(f)


train['anonymousFeature1'] = train['anonymousFeature1'].fillna(a)
# train['anonymousFeature4'] = train['anonymousFeature4'].fillna(b)
# train['anonymousFeature8'] = train['anonymousFeature8'].fillna(c)
# train['anonymousFeature9'] = train['anonymousFeature9'].fillna(d)
# train['anonymousFeature10'] = train['anonymousFeature10'].fillna(e)
train['anonymousFeature11'] = train['anonymousFeature11'].fillna(f)

test['anonymousFeature1'] = test['anonymousFeature1'].fillna(a)
# test['anonymousFeature4'] = test['anonymousFeature4'].fillna(b)
# test['anonymousFeature8'] = test['anonymousFeature8'].fillna(c)
# test['anonymousFeature9'] = test['anonymousFeature9'].fillna(d)
# test['anonymousFeature10'] = test['anonymousFeature10'].fillna(e)
test['anonymousFeature11'] = test['anonymousFeature11'].fillna(f)

2.2 提取时间特征

# # 时间处理(提取年月日)
train['tradeTime'] = pd.to_datetime(train['tradeTime'])
train['registerDate'] = pd.to_datetime(train['registerDate'])
train['licenseDate'] = pd.to_datetime(train['licenseDate'])
test['tradeTime'] = pd.to_datetime(test['tradeTime'])
test['registerDate'] = pd.to_datetime(test['registerDate'])
test['licenseDate'] = pd.to_datetime(test['licenseDate'])


train['tradeTime_year'] = train['tradeTime'].dt.year
train['tradeTime_month'] = train['tradeTime'].dt.month
train['tradeTime_day'] = train['tradeTime'].dt.day
train['registerDate_year'] = train['registerDate'].dt.year
train['registerDate_month'] = train['registerDate'].dt.month
train['registerDate_day'] = train['registerDate'].dt.day
test['tradeTime_year'] = test['tradeTime'].dt.year
test['tradeTime_month'] = test['tradeTime'].dt.month
test['tradeTime_day'] = test['tradeTime'].dt.day
test['registerDate_year'] = test['registerDate'].dt.year
test['registerDate_month'] = test['registerDate'].dt.month
test['registerDate_day'] = test['registerDate'].dt.day

2.3 匿名特征13的特征处理

代码不完整，差time_format函数，完整代码请下载

# # 匿名特征13(转化时间格式)
train = train[train['anonymousFeature13'].notna()]
train = train.reset_index()
test = test[test['anonymousFeature13'].notna()]
test = test.reset_index()

train['anonymousFeature13'].progress_apply(time_format)
test['anonymousFeature13'].progress_apply(time_format)
train['anonymousFeature13'] = pd.to_datetime(train['anonymousFeature13'])
test['anonymousFeature13'] = pd.to_datetime(test['anonymousFeature13'])
train['anonymousFeature13_year'] = train['anonymousFeature13'].dt.year
train['anonymousFeature13_month'] = train['anonymousFeature13'].dt.month
test['anonymousFeature13_year'] = test['anonymousFeature13'].dt.year
test['anonymousFeature13_month'] = test['anonymousFeature13'].dt.month

2.4 匿名特征12的处理

series1 = train['anonymousFeature12'].str.split('*', expand=True)
train['length'] = series1[0]
train['width'] = series1[1]
train['high'] = series1[2]
series2 = test['anonymousFeature12'].str.split('*', expand=True)
test['length'] = series2[0]
test['width'] = series2[1]
test['high'] = series2[2]

train['length'] = train['length'].astype(float)
train['width'] = train['width'].astype(float)
train['high'] = train['high'].astype(float)

test['length'] = test['length'].astype(float)
test['width'] = test['width'].astype(float)
test['high'] = test['high'].astype(float)

2.5 匿名特征11的处理

代码不完整，差dict字典，完整代码下载：

train['anonymousFeature11'] = train['anonymousFeature11'].map(dict)
test['anonymousFeature11'] = test['anonymousFeature11'].map(dict)

2.6 存储为csv

总共挖掘了33个特征，除了以上已有的特征提取外，还可以构造交叉特征，挖掘其他的特征。此处省略

train.to_csv('clear_train.csv',index=0)
test.to_csv('clear_test.csv',index=0)

3 特征筛选和降维

略。。。

4 模型训练

导入包

from sklearn.metrics import mean_squared_error
from sklearn.model_selection import StratifiedKFold, KFold
from sklearn.model_selection import train_test_split
from sklearn.metrics import mean_squared_error
from sklearn.ensemble import RandomForestRegressor
import lightgbm as lgb
from sklearn.tree import DecisionTreeRegressor
from sklearn.svm import SVR
import pandas as pd
import warnings
from sklearn.preprocessing import scale
from sklearn.model_selection import cross_val_score
import lightgbm as lgb
from sklearn.model_selection import KFold
import xgboost as xgb
from catboost import CatBoostRegressor
import time
import numpy as np
from sklearn.preprocessing import StandardScaler

读取数据

train = pd.read_csv('clear_train.csv')
test = pd.read_csv('clear_test.csv')

筛选数据并归一化，大于75的为异常值，直接舍弃

n_price = 75
train_X = train[train['price'] < n_price]
# 使用对数的右偏变换函数，将数据分布转为近似正态分布
train_X['price'] = np.log1p(train_X['price'])
train_y = train_X['price']
del train_X['price']
scaler = StandardScaler()
train_x = scaler.fit_transform(train_X)
test_x = scaler.fit_transform(test)

设计准确率评价函数

params = {'learning_rate': 0.01,
          'boosting_type': 'gbdt',
          'objective': 'regression_l1',
          'metric': 'mae',
          'min_child_samples': 46,
          'min_child_weight': 0.01,
          'feature_fraction': 0.8,
          'bagging_fraction': 0.8,
          'bagging_freq': 2,
          'num_leaves': 32,
          'max_depth': 8,
          'n_jobs': -1,
          'seed': 2019,
          'verbose': -1,
          }


def Accuracy(y_true, y_pred):
    """
    参数:
    y_true -- 测试集目标真实值
    y_pred -- 测试集目标预测值
    
    返回:
    mape -- MAPE 评价指标
    """
	#略。。
    return Accuracy

5折划分训练，并预测测试集，生成提交文件

val_pred = np.zeros(len(train_x))
val_true = np.zeros(len(train_x))
preds = np.zeros(len(test_x))
folds = 5
# seeds = [1234]
# for seed in seeds:
kfold = KFold(n_splits=folds, shuffle=True, random_state=4321)
for fold, (trn_idx, val_idx) in enumerate(kfold.split(train_x, train_y)):
    print('fold ', fold + 1)
    x_trn, y_trn, x_val, y_val = train_x[trn_idx], train_y.iloc[trn_idx], train_x[val_idx], train_y.iloc[val_idx]
    train_set = lgb.Dataset(x_trn, y_trn)
    val_set = lgb.Dataset(x_val, y_val)

    model = lgb.train(params, train_set, num_boost_round=5000,
                      valid_sets=(
                          train_set, val_set), early_stopping_rounds=500,
                      verbose_eval=False)
    val_pred[val_idx] += model.predict(x_val, predict_disable_shape_check=True)
    preds += model.predict(test_x, predict_disable_shape_check=True) / folds
    val_true[val_idx] += y_val
Accuracy = Accuracy(val_true, val_pred)
print('-'*120)
print('Accuracy ', round(Accuracy, 5))
pd.DataFrame(preds).to_csv('估价模型结果.csv',header=0)

本地验证准确率为0.99+

生成的提交的数据如下