August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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117
第
14
章
将行转为列
在上一章中，我们介绍了第一种类型的数据转换：从列到行。在这一章中，我们将
探讨如何以相反的方向（从行到列）进行数据转换（有时也称“
unpivot
，逆 转 换 ”）。
首先，我们将看看何时需要将行转为列，然后来学习如何在
Prep Builder
中实际应
用这种技术。
14.1
何时使用行到列的数据转换
行到列的数据转换选项是在后来的工具版本中才添加到
Prep Builder
中的，这个功
能是一个很好的补充，可以避免在常见应用场景中通过变通手段来实现相关功能。
数据经常来自将多个度量或维度保存在一列中的源。为了使
Tableau Desktop
中的数
据分析更容易，需要将这些数据分离出来，变成将每个度量或维度放在独立的列中。
如果不把它们分开，从技术上讲，仍然可以在
Tableau Desktop
中分析数据（见图
14-1
）。
但是，如果想创建一个比较两个度量的散点图，如果不创建多个计算或者重复数据
字段并对它们进行过滤，你就没法实现这样的功能。需要记住，数据准备的目的是
让最终用户更容易进行数据分析。
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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.
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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.