November 2023
Intermediate to advanced
512 pages
11h 53m
Chinese
Content preview from 利用 Python 进行数据分析：原书第 3 版
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138
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第
5
章
虽然可以用这种方式用标签选取数据，但是更可取的方式是使用特殊的 loc 运算符选取
索引值：
loc 的方式更为可取，因为用 [] 进行索引时，针对整数的处理有所不同。如果索引包含
整数，常规的基于 [] 的索引会将整数用作标签，因此索引的选取取决于数据类型。例如：
pandas
入门
|
139
使用 loc 时，如果索引中不含整数，则表达式 obj.loc[[0, 1, 2]] 会失效：
loc 运算符只使用标签，iloc 运算符只使用整数。无论索引是否包含整数，都能使用
iloc：
还可以使用标签进行切片，但区别于普通
Python
的切片方式，loc 的切片是
包含末端的：
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第
5
章
使用以上切片方法可以对
Series
的相应部分进行赋值：
像函数那样调用 loc 和 iloc 是新手常犯的错误，正确的方式是用方括号
进行索引。方括号不仅用于切片索引，还用于对
DataFrame
的多个轴进行
索引。
用单个值或序列对
DataFrame
进行索引，以获取单列或多列：
pandas
入门
|
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