从哈希中删除重复项

Question

I have the following array of hashes

input = [
  {'line_number' => 1, 'name' => 'Name1', 'value' => 'Value'},
  {'line_number' => 1, 'name' => 'Name2', 'value' => 'Value'},
  {'line_number' => 2, 'name' => 'AnotherName', 'value' => 'AnotherValue'}
]

I want, which after checking for uniqueness the output would be

output = [
  {'line_number' => 1, 'name' => 'Name2', 'value' => 'Value'},
  {'line_number' => 2, 'name' => 'AnotherName', 'value' => 'AnotherValue'}
]

because simple uniqueness

input.uniq! { |i| i['line_number'] }

give me

 output = [ {'line_number' => 1, 'name' => 'Name1', 'value' => 'Value'}, {'line_number' => 2, 'name' => 'AnotherName', 'value' => 'AnotherValue'} ] 

Thanks in advance.

Answer 1

If you want to keep the last one, you can do this

input.each_with_object({}) {|h, obj| obj[h['line_number']] = h}.values
# => [{"line_number"=>1, "name"=>"Name2", "value"=>"Value"},
# =>  {"line_number"=>2, "name"=>"AnotherName", "value"=>"AnotherValue"}]

Answer 2

这个问题很奇怪，但是也许可以帮助您：

input.group_by { |i| i['line_number'] }.values.map! { |i| i.last }

Answer 3

如果要保留最后一个而不是第一个，为什么不简单

input.reverse.uniq { |i| i['line_number'] }

Answer 4

input.each_with_object({}) { |g,h| h.update(g['line_number']=>g) }.values
  #=> [{"line_number"=>1, "name"=>"Name2", "value"=>"Value"},
  #    {"line_number"=>2, "name"=>"AnotherName", "value"=>"AnotherValue"}]