August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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160
｜
第
18
章
18.3.3
描述
描述是大多数新用户了解所选函数实际作用的地方。函数的名称通常是一个很好的
线索，但描述提供了更多的细节，说明该函数到底是用来做什么的。
18.3.4
示例
示例可以帮助各个级别的用户演示
date_part
的含义，或者如何编写
start_of_
week
代码。有些例子并不是最容易理解的，所以在网上搜索是一个很好的增进你的
理解的方法。只要在搜索引擎中输入“
Tableau
”和函数名称，你就会发现更多的示例，
而且往往还有一两篇博文。
18.4
建立计算
有了所有这些来自
Tableau Prep
工具的支持，建立计算应该很容易，对吧？好吧，
其实并不尽然。计算可能真的很复杂，一个简单的排版错误就会破坏计算。让我们
来看一些例子，其既可能是完善的计算，也可以是潜在的陷阱。
18.4.1
当计算顺利进行时
当你使用一个或多个
Tableau Prep
认为格式正确的函数时，计算就会顺利进行。在
图
18-7
中计算的左下角，
Prep Builder
和
Tableau Desktop
一样，表明它是
valid
（有
效的）。
计算有效并不意味着该计算在你的预期目标方面是正确的。验证数据是否正确取决
于你自己，因为只有你知道想做的是什么。
这个界面中的关键要素之一是计算字段中使用的颜色编码：
•
蓝色代表有效函数。
•
橙色代表数据集中的数据字段。如果它们以黑色出现，则要么缺少了方括号，
要么拼错了数据字段名。需要记住，要调用字段，你必须匹配其名称中的大写
和标点符号（例如，空格）。
｜
161
计算
图
18
-
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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.