July 2019
Intermediate to advanced
365 pages
8h 13m
Chinese
Content preview from Python机器学习手册：从数据预处理到深度学习
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3.4
根据条件语句来选择行
｜
39
由于在数据清洗时会频繁使用
loc
和
iloc
，所以有必要熟悉它们。
3.4
根据条件语句来选择行
问题描述
根据某个条件语句来选择数据帧的行数据。
解决方案
利用
pandas
很容易实现这个功能。例如，选择泰坦尼克号上所有女性乘客的数据 ：
#
加载库
import pandas as pd
#
创建
URL
url = 'https://tinyurl.com/titanic-csv'
#
加载数据
dataframe = pd.read_csv(url)
#
展示
Sex
列的值是
female
的前两行
dataframe[dataframe['Sex'] == 'female'].head(2)
Name PClass Age Sex Survived SexCode
0 Allen, Miss Elisabeth Walton 1st 29.0 female 1 1
1 Allison, Miss Helen Loraine 1st 2.0 female 0 1
我们一起来看这个解决方案是怎么做的。
dataframe['Sex'] == 'female'
就是条件
语句。我们在它的外面包了一层
dataframe[]
来告诉
pandas
：“选择数据帧中所有
dataFrame['Sex']
的值是
'female'
的行数据”。
要同时使用多个条件语句也很简单。下面的代码就筛选出了所有年龄大于或等于
65
岁
的女性乘客的行数据 ：
#
过滤行
dataframe[(dataframe['Sex'] ...
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