string 检查列表中的值是否是字符串的一部分
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Checking if values in List is part of String
提问by Sibi
I have a string like this:
我有一个这样的字符串：
val a = "some random test message"
I have a list like this:
我有一个这样的清单：
val keys = List("hi","random","test")
Now, I want to check whether the string acontains any values from keys. How can we do this using the in built library functions of Scala ?
现在，我想检查字符串是否a包含来自keys. 我们如何使用 Scala 的内置库函数来做到这一点？
( I know the way of splitting ato List and then do a check with keyslist and then find the solution. But I'm looking a way of solving it more simply using standard library functions.)
（我知道拆分a为 List 的方法，然后使用keyslist进行检查，然后找到解决方案。但我正在寻找一种使用标准库函数更简单地解决它的方法。）
回答by rarry
Something like this?
像这样的东西？
keys.exists(a.contains(_))
Or even more idiomatically
或者更地道
keys.exists(a.contains)
回答by Rick-777
The simple case is to test substring containment (as remarked in rarry's answer), e.g.
简单的情况是测试子字符串包含（如rarry的答案中所述），例如
keys.exists(a.contains(_))
You didn't say whether you actually want to find whole word matches instead. Since rarry's answer assumed you didn't, here's an alternative that assumes you do.
你没有说你是否真的想找到整个单词匹配。由于rarry的回答假设您没有，这里有一个假设您有的替代方案。
val a = "some random test message"
val words = a.split(" ")
val keys = Set("hi","random","test") // could be a List (see below)
words.exists(keys contains _)
Bear in mind that the listof keys is only efficient for small lists. With a list, the containsmethod typically scans the entire list linearly until it finds a match or reaches the end.
请记住，键列表仅对小列表有效。对于列表，该contains方法通常线性扫描整个列表，直到找到匹配项或到达末尾。
For larger numbers of items, a set is not only preferable, but also is a more true representation of the information. Sets are typically optimised via hashcodes etc and therefore need less linear searching - or none at all.
对于数量较多的项目，集合不仅更可取，而且是信息的更真实表示。集合通常通过哈希码等进行优化，因此需要较少的线性搜索 - 或者根本不需要。
