在 Ruby/Rails 中合并数组
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Merge arrays in Ruby/Rails
提问by Croaton
How can I merge two arrays? Something like this:
如何合并两个数组？像这样的东西：
@movie = Movie.first()
@options = Movie.order("RANDOM()").first(3).merge(@movie)
But it doesn't work.
但它不起作用。
In @optionsI need an array with four elements includes @movie.
在@options我需要一个包含四个元素的数组包括@movie.
回答by Nick Veys
Like this?
像这样？
?? irb
2.2.2 :001 > [1,2,3] + [4,5,6]
=> [1, 2, 3, 4, 5, 6]
But you don't have 2 arrays.
但是你没有 2 个数组。
You could do something like:
你可以这样做：
@movie = Movie.first()
@options = Movie.order("RANDOM()").first(3).to_a << @movie
回答by joshua.paling
There's two parts to this question:
这个问题有两个部分：
How to "merge two arrays"? Just use the
+method:[1,2,3] + [2,3,4] => [1, 2, 3, 2, 3, 4]How to do what you want? (Which as it turns out, isn't merging two arrays.) Let's first break down that problem:
@movieis an instance of yourMoviemodel, which you can verify with@movie.class.name.@optionsis anArray, which you can verify with@options.class.name.All you need to know now is how to append a new item to an array (i.e., append your
@movieitem to your@optionsarray)You do that using the double shovel:
@options << @moviethis is essentially the same as something like:
[1,2,3] << 4 => [1,2,3,4]
如何“合并两个数组”？只需使用以下
+方法：[1,2,3] + [2,3,4] => [1, 2, 3, 2, 3, 4]如何做你想做的事？（事实证明，这不是合并两个数组。）让我们首先分解这个问题：
@movie是您的Movie模型的一个实例，您可以使用@movie.class.name.@options是Array，您可以使用 进行验证@options.class.name。您现在需要知道的是如何将新项目附加到数组中（即，将您的
@movie项目附加到@options数组中）你使用双铲来做到这一点：
@options << @movie这基本上与以下内容相同：
[1,2,3] << 4 => [1,2,3,4]
回答by spickermann
@movieisn't an array in your example, it is just a single instance of a movie. This should solve your problem:
@movie在您的示例中不是数组，它只是电影的单个实例。这应该可以解决您的问题：
@options << @movie
回答by Ana María Martínez Gómez
To merge (make the union of) arrays:
合并（合并）数组：
[1, 2, 3].union([2, 4, 6]) #=> [1, 2, 3, 4, 6] (FROM RUBY 2.6)
[1, 2, 3] | [2, 4, 6] #=> [1, 2, 3, 4, 6]
To concat arrays:
连接数组：
[1, 2, 3].concat([2, 4, 6]) #=> [1, 2, 3, 2, 4, 6] (FROM RUBY 2.6)
[1, 2, 3] + [2, 4, 6] #=> [1, 2, 3, 2, 4, 6]
To add element to an array:
向数组添加元素：
[1, 2, 3] << 4 #=> [1, 2, 3, 4]
But it seems that you don't have arrays, but active records. You could convert it to array with to_a, but you can also do directly:
但似乎您没有数组，而是活动记录。您可以使用 将其转换为数组to_a，但您也可以直接执行以下操作：
Movie.order("RANDOM()").first(3) + [@movie]
which returns the array you want.
它返回你想要的数组。
回答by Ayman Hussain
Well, If you have an element to merge in an array you can use <<:
好吧，如果你有一个元素要合并到一个数组中，你可以使用<<：
Eg: array = ["a", "b", "c"], element = "d"
array << element
=> ["a", "b", "c", "d"]
Or if you have two arrays and want duplicates then make use of +=or simply +based on your requirements on mutability requirements:
或者，如果您有两个数组并想要重复，则使用+=或简单地+基于您对可变性要求的要求：
Eg: array_1 = [1, 2], array_2 = [2, 3]
array_1 += array_2
=> [1, 2, 2, 3]
Or if you have two arrays and want to neglect duplicates then make use of |=or simply |:
或者，如果您有两个数组并想忽略重复项，请使用|=或简单地使用|：
Eg: array_1 = [1, 2], array_2 = [2, 3]
array_1 |= array_2
=> [1, 2, 3]
