Question

嘿，伙计们，我有一个问题。我想将数组。[[1, [-1, 1]], [1, [20, 8]], [1, [30, 4]], [1, [40, 2]], [1, [41, 6]], [1, [70, 243]]]转换为此样式[1,[[-1,1],[20,8],[30,4]...]或哈希[1 =＆gt; ...] 我怎么能这样做？谢谢！

Answer 1

Dict方法：

array = [your array]
dict = {}
array.each{ |a| (dict[a[0]] ||= []) << a[1] }

为了清楚起见，查克的建议将带来：

array = [your array]
dict = Hash.new {|h,k| h[k] = []}
array.each{ |a| dict[a[0]] << a[1] }

然后，您可以按照您想要的样式从中获取数组：

new_arr = dict.select{|k,v| [k, v]}

哪个会给你：

[[1, [[-1, 1], [20, 8], [30, 4], [40, 2], [41, 6], [70, 243]]]]

注意额外的数组，因为如果你有2开头的数组，你最后会有另一个数组。因此new_arr[0]会为您提供您最初寻找的数组。

Answer 2

如果您希望它为Hash，则只需

h = Hash[ary.group_by(&:first).map {|k, v| [k, v.map(&:last)] }]

如果您想将其作为Array，则只需将Hash转换为Array：

a = *h

Answer 3

你可以这样做：

array = [[1, [-1, 1]], [1, [20, 8]], [1, [30, 4]],
         [1, [40, 2]], [1, [41, 6]], [1, [70, 243]]]

# map into hashes that can be merged together
hashes = array.map do |key,value|
  { key => [value] }
end

# fold all hashes into one hash by merging the values by key
merged_hash = hashes.inject({}) do |accu,value|
  accu.merge!(value) {|_,o,n| o|n }
end

这可以写成一个不那么容易的单行词：

array.map{|k,v|{k=>[v]}}.inject({}){|a,v|a.merge!(v){|_,o,n|o|n}}
#==> {1=>[[-1, 1], [20, 8], [30, 4], [40, 2], [41, 6], [70, 243]]}

一个ruby数组问题！

3 个答案: