Question

在没有过多循环的情况下，有没有直接的方法来执行以下操作？

myArray = [["a","b"],["c","d"],["e","f"]]
if myArray.includes?("c")
   ...

我知道如果它只是一个正常的字符数组，这样可以正常工作...但是我想要一个字符数组的数组同样优雅（用于帮助将其转换为元组数组的奖励点）。< / p>

Answer 1

如果你只需要一个真/假答案，你可以flatten数组和电话包括：

>> myArray.flatten.include?("c")
=> true

Answer 2

您可以使用assoc：

my_array = [['a', 'b'], ['c', 'd'], ['e', 'f']]

if my_array.assoc('c')
  # ...

它实际上返回整个子阵列：

my_array.assoc('c') #=> ["c", "d"]

如果没有匹配，请

或nil：

my_array.assoc('g') #=> nil

还有rassoc来搜索第二个元素：

my_array.rassoc('d') #=> ["c", "d"]

Answer 3

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Severe:   ContainerBase.addChild: start: 
org.apache.catalina.LifecycleException:    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userDetailsService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException:   Could not autowire field: com.lisawestberg.noxml.dao.FacultyDAO com.lisawestberg.noxml.service.LoginService.dao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.lisawestberg.noxml.dao.FacultyDAO] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.apache.catalina.core.StandardContext.start(StandardContext.java:5985)

Answer 4

您可以使用Array#any?

myArray = [["a","b"],["c","d"],["e","f"]]
if myArray.any? { |x| x.includes?("c") }
  # some code here

Answer 5

find_index方法适用于此：

myArray = [["a","b"],["c","d"],["e","f"]]
puts "found!" if myArray.find_index {|a| a[0] == "c" }

返回值是对的数组索引，如果找不到对，则为nil。

您可以通过这种方式捕捉配对的价值（如果没有找到nil）：

myArray.find_index {|a| a[0] == "c" } || [nil, nil])[1]
# => "d"

如何检查数组数组中是否存在键？

5 个答案: