1

我有四种尺寸，每种尺寸都以平方英尺为单位：

# The sizes. Sizes are in sq ft (min, max)
size_hash = {
  'Large'  => [70,139],
  'Medium' => [15,69],
  'Small'  => [1,14]
}

如果给我 number 40，我如何Medium从数组中返回大小？

我需要做这样的事情吗？：

# The sizes. Sizes are in sq ft (min, max)
size_hash = {
  [70..139]  => 'Large',
  #... etc
}
4

4 回答 4

5

您可以使用proc：

size_store = proc{ |n|
  case n
  when 70..139
    'Large'
  when 15..69
    'Medium'
  when 1..14
    'Small'
  end
}
# USAGE: size_store[40]
于 2012-11-25T04:04:00.300 回答
4 
size_hash.find{|_, (min, max)| (min..max) === 40}[0]
# => "Medium"

但我认为首先存储范围而不是最小值和最大值是一个更好的主意。

size_hash = {
    'Large'  => 70..139,
    'Medium' => 15..69,
    'Small'  => 1..14,
}

size_hash.find{|_, r| r === 40}[0]
# => "Medium"
于 2012-11-25T04:41:30.273 回答
2

另一个解决边缘情况的解决方案......

@size_hash = {
  'Large'  => 70..139,
  'Medium' => 15..69,
  'Small'  => 1..14,
}

some_value = @size_hash["Small"]
@min = some_value.first
@max = some_value.last
@size_hash.each_pair do |k, v|
    @min = [@min, v.first].min
    @max = [@max, v.last].max
end

puts "size_hash goes from #{@min} to #{@max}"

    # Given a number, return the name of the range which it belongs to.
def whichSize(p_number)
    @size_hash.each_pair do |k, v|
        return k if v.include?(p_number)
    end

    return "below minimum" if p_number < @min
    "above maximum" if p_number > @max
end

# test
[-10, 0, 1, 10, 14, 15, 20, 69, 70, 80, 139, 140, 1000].each do |e|
    puts "size of #{sprintf("%4s", e)} is #{whichSize(e)}"
end

$ ruby -w t.rb 
size_hash goes from 1 to 139
size of  -10 is below minimum
size of    0 is below minimum
size of    1 is Small
size of   10 is Small
size of   14 is Small
size of   15 is Medium
size of   20 is Medium
size of   69 is Medium
size of   70 is Large
size of   80 is Large
size of  139 is Large
size of  140 is above maximum
size of 1000 is above maximum
于 2012-11-25T14:21:19.230 回答
1

如果您将范围存储为键，您可以这样做：

size_hash = Hash.new {|hash, key| hash.find {|range,_| range.cover?(key) }.last }.merge({
  (1..14)   => 'Small',
  (15..69)  => 'Medium',
  (70..139) => 'Large'
})

这会在哈希中设置一个默认过程，因此当您查找一个值时，例如size_hash[9]，将返回覆盖该值的第一个范围。请记住，这不会处理超出范围的错误。

于 2012-11-25T04:02:56.683 回答