August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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155
第
18
章
计算
一般来说，数据很难直接从源头上为后续分析提供完美的支持。计算是使得数据能
够适用于回答相关问题的关键工具之一。很多人害怕计算，但本章提供了一些简单
的技巧，可以让计算不那么令人生畏，并释放计算的力量和灵活性。
18.1
计算在数据准备中的作用是什么
在最简单的层面上，计算可以创建一个新的数据字段或覆盖一个现有的数据字段。
大多数计算使用现有的数据字段作为基础来形成新的数据字段。新的或修改后的字
段被称为计算字段，表明它并不是源于准备流程中的初始输入数据。新的数据字段
是基于以下原因创建的：
•
数据清理（删除多余字符、分割名称等）。
•
算术运算（求和、平均或乘法运算）。
•
合并多个字段（来自日期、电子邮件地址等字段）。
由这些操作产生的计算数据字段可用于分析或进一步的数据准备。计算会在
Table
Prep
中创建新字段，除非计算的名称与现有数据字段相同，而在这种情况下，原始
数据字段会被覆盖。
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.