相关： Python数据分析招式：pandas库提取清洗排序-1
要点：
- 数据的字符处理
- 数据的过滤
- 数据的分组
- 数据的透视表
引入数据
# -*- coding: utf-8 -*- # @File : 数据集的处理.py # @Date : 2018-06-03 import pandas as pd file = "data/train.csv" df = pd.DataFrame(pd.read_csv(file)) print(df.head(3)) """ PassengerId Survived Pclass ... Fare Cabin Embarked 0 1 0 3 ... 7.2500 NaN S 1 2 1 1 ... 71.2833 C85 C 2 3 1 3 ... 7.9250 NaN S [3 rows x 12 columns] """
1、数据集的字符处理
# 对列的处理 mapping ={ 'PassengerId': '乘客编号', 'Survived':'是否获救', 'Name':'姓名', 'Pclass':'船舱等级','Sex':'性别', 'Age':'年龄','SibSp':'兄弟姐妹数', 'Parch':'父母小孩数','Ticket':'船票', 'Fare':'船票费' } ret = df.rename(columns=mapping) print(ret.head(3)) """ 乘客编号 是否获救 船舱等级 ... 船票费 Cabin Embarked 0 1 0 3 ... 7.2500 NaN S 1 2 1 1 ... 71.2833 C85 C 2 3 1 3 ... 7.9250 NaN S [3 rows x 12 columns] """ # 对数据集里面的特定字符串进行替换 ret = df['Sex'].map({'female':'女','male':'男'}) print(ret.head(3)) """ [3 rows x 12 columns] 0 男 1 女 2 女 Name: Sex, dtype: object """ # 对列的字符进行替换, 只保留数字部分 # contains,split,match,findall,endswith df['Embarked']=df['Embarked'].replace(regex='[CS]', value='xxx') print(df.head(3)) """ PassengerId Survived Pclass ... Fare Cabin Embarked 0 1 0 3 ... 7.2500 NaN xxx 1 2 1 1 ... 71.2833 C85 xxx 2 3 1 3 ... 7.9250 NaN xxx [3 rows x 12 columns] """
2、数据集的过滤
# 用逻辑表达式组合过滤 ==, != ret = df[(df['Sex']=='female')&(df['Age']>10)] print(ret.head(3)) """ PassengerId Survived Pclass ... Fare Cabin Embarked 1 2 1 1 ... 71.2833 C85 xxx 2 3 1 3 ... 7.9250 NaN xxx 3 4 1 1 ... 53.1000 C123 xxx [3 rows x 12 columns] """ # query函数 ret = df.query('Age==[10, 20]') print(ret[["Name", "Age"]].head(3)) """ Name Age 12 Saundercock, Mr. William Henry 20.0 91 Andreasson, Mr. Paul Edvin 20.0 113 Jussila, Miss. Katriina 20.0 """
3、数据的分类
# 用where函数 import numpy as np ret=np.where(df['Age']>=18) # apply函数 def convert_age(age): if age> 0 and age < 10: return "小孩" elif age < 30: return "大人" else: return "老人" df["年龄分类"] = df['Age'].apply(convert_age) print(df[["Name", "Age", "年龄分类"]].sample(3)) """ Name Age 年龄分类 624 Bowen, Mr. David John "Dai" 21.0 大人 880 Shelley, Mrs. William (Imanita Parrish Hall) 25.0 大人 471 Cacic, Mr. Luka 38.0 老人 """
4、 数据的切片和透视表
# groupby函数 print(df.groupby('Sex')[['Name', 'Sex']].count()) """ Name Sex Sex female 314 314 male 577 577 """ # 对数据进行轴切片分析 ret = df.groupby(['Survived','Pclass'])['Age'].agg(['size','max','min','mean']) print(ret) """ Survived Pclass 0 1 80 71.0 2.00 43.695312 2 97 70.0 16.00 33.544444 3 372 74.0 1.00 26.555556 1 1 136 80.0 0.92 35.368197 2 87 62.0 0.67 25.901566 3 119 63.0 0.42 20.646118 """ # 数据透视表 ret = df.pivot_table(columns=['Sex'],index=['Survived','Pclass'],values='Age', aggfunc={'Age':[np.mean,min,max]}) print(ret) """ max mean min Sex female male female male female male Survived Pclass 0 1 50.0 71.0 25.666667 44.581967 2.00 18.00 2 57.0 70.0 36.000000 33.369048 24.00 16.00 3 48.0 74.0 23.818182 27.255814 2.00 1.00 1 1 63.0 80.0 34.939024 36.248000 14.00 0.92 2 55.0 62.0 28.080882 16.022000 2.00 0.67 3 63.0 45.0 19.329787 22.274211 0.75 0.42 """
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