Ruby数组按月分组

require 'date'

def group_by_month(array)
  result = Hash.new { |hash, key| hash[key] = [] }
  
  array.each do |date_str|
    date = Date.parse(date_str)
    formatted_date = date.strftime("%Y-%m")
    result[formatted_date] << date_str
  end

  result
end

# 示例用法
dates = ['2022-01-01', '2022-01-10', '2022-02-05', '2022-02-20', '2022-03-15']
grouped_dates = group_by_month(dates)

grouped_dates.each do |month, dates|
  puts "#{month}: #{dates}"
end

2022-01: ['2022-01-01', '2022-01-10']
2022-02: ['2022-02-05', '2022-02-20']
2022-03: ['2022-03-15']