August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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｜
131Prep Builder
中的汇总功能
图
15
-
17
：增加要分组的数据字段数量，进一步分列总成本
15.4
剩下的数据在哪里
在汇总操作之后，可能还要进行其他的数据准备步骤。汇总步骤的挑战在于，你得
到的输出只有满足分组和汇总设置中的字段。
让我们回到第二个
Group by
（分组）的例子，其中我们只按项目类型进行分组，并
看看流向下一个清理步骤的数据内容（见图
15-18
）。
我们有三种不同类型的项目，所以我们有三行数据，但需要注意的是，我们把其他
列的数据都落下了。要想把这些数据找回来，需要把刚才添加的总数加入原始数据
集中。在汇总步骤之前，从哪里抽取数据，取决于对该数据做了哪些更改。流程看
起来如图
15-19
所示。
132
｜
第
15
章
图
15
-
18
：汇总步骤只输出分组后或汇总后的数据
图
15
-
19
：Self-join（自连接）以重新引入在汇总步骤中丢失的数据
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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.