August 2022
Beginner to intermediate
463 pages
9h 22m
Chinese
Content preview from Tableau Prep即学即用
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258
第
29
章
处理多余字符
在清理数据时，在数据字段中发现非预期的字符可能会导致重大问题。这些问题可
能发生在你的数据准备过程中的多个阶段：加载、使用和输出数据。因此，本章的
重点是建立什么是多余的字符、它们带来的问题以及如何删除它们的理解。
29.1
什么是多余的字符
多余的字符是指数据字段中你不需要的或者会给你的数据输出带来潜在问题的字母、
数字或符号。数据软件通常对其处理的内容非常精确，这样做是对的，否则，它很
容易产生错误的输出。例如，如果一个数据字段内有不同的数据类型，就会影响到
一个字段是否可以进行逻辑汇总。让我们来看看当数据字段加载到
Prep Builder
中时，
可能会受到多余字符影响的三种主要数据类型：
数字字段
如果一个非数字字符被加载到一个数字字段中，则该字段将被导入为一个字符
串，因此不能再用于汇总。例如，
10+1c3
应该等于什么？正如你所看到的，这
种计算是不可能的，这就是为什么一个数字字段必须只包含数字值的原因。
日期
如果在字段中发现一个非数字字符，而该字段只期望有日期值，那么带有多余
字符的日期值将显示为空，因为日期的格式是无效的。例如，
30/0/4/2023
。
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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.