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.
｜
309
分析计算
图
34
-
12
：设置行号随时间增加
这里行号随着订单日期值的增加而递增（见图
34-13
）。
图
34
-
13
：行号计算结果
ROW_NUMBER()
函数可以帮助你在做比较复杂的清理任务时对数据进行排序，使其更
容易分析。
34.3
应用案例
在
Prep
中，有许多应用案例可以从分析计算中受益。本节将只介绍几个例子。
34.3.1
筛选前
N
条记录
在
Prep Builder
的早期版本中，创建“
Top N
”（前
N
个）过滤器是一个相当困难的
问题。对数据进行排名涉及复杂的自连接和棘手的连接条件。现在，排名功能可以
通过过滤轻松生成“
Top N
”的记录列表。让我们回到之前的子类别销售排名，并
将其过滤到仅按销量排名的前
5
个子类别（见图
34-14
）。
310
｜
第
34
章
图
34
-
14
：计算前
5
名的排名
这里只返回
Top 5
（排名前
5
）的值（见图
34-15
）。
图
34
-
15
：应用 Top
5
过滤器后的结果数据集
34.3.2
过滤掉一定比例的数据
使用与排名
Top 5
类似的技术，可以设置希望返回数据集中的多少内容（基于数据
中的一个值）。如果数据量（在本例中为
Sub-Category
子类别）会随着时间的推移
而增加，但你仍然希望返回相同尺寸的样本，那么这是一种有用的技术（见图
34-
16
）。
图
34
-
16
：计算一个排名以返回一个百分比的数据 ...
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.