August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.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.
｜
201
创建附加数据
（汇总）步骤，在该步骤中，你可以设置这些度量值的计算方式（例如，区域级别
的总销售额）。
22.1.2
数据连接中的重复记录
创建附加数据行的一种方法是将数据集连接在一起（见图
22-2
）。如果你将某个数
据集连接到另一个数据集，其中的粒度是相同的，或者附加了一个值，那么如果有
匹配的数据字段，就不太可能生成重复的数据行。但是，如果粒度级别不同，或者
连接条件字段不匹配，那么就有可能生成重复的数据行。
图
22
-
2
：Prep Builder 中的连接步骤
换句话说，如果被添加的数据集的粒度较高，那么连接很可能会通过重复原始数据
集的记录来增加行。任何形式的无意重复都会妨碍分析。
连接在第
16
章和第
32
章有更详细的介绍。
那么应该采取什么方法来创建附加的列或行呢？
22.2
创建附加的列
正如本节将讨论的那样，可以有多种方法在数据集中创建额外的列。
22.2.1
使用计算
创建计算从而向数据集添加新列（除非该计算与现有数据字段名称相同，在这种情
况下，原字段将被覆盖）。计算可以是数据清理，也可以是数据创建函数。
202
｜
第
22
章
数据清理
数据清理计算是将较长的字符串拆分，或将现有的数据字段转换为对分析更有
用的新列。在图
22-3
中，我们需要为英镑（
GBP
）值创建一个单独的列，在它
从美元（
USD
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.