在ruby中，在一个日期范围内具体发生了多少次?

i have two dates i.e.

我有两个约会。

start date = "2013-06-01" 
end date = "2013-12-01"

I am trying to achieve how many times mondays and tuesdays occur within this date range?

我正在努力实现在这个日期范围内星期一和星期二发生了多少次?

specific_days = 2 #monday and tuesday
total days = end_date - start_date 
total_weeks = total_days/7
total_specific_days = total_weeks * specific_days

but this doesnt assures the mondays and tuesdays occurences

但这并不能保证周一和周二会发生

4 个解决方案

#1

This question is very similar to How do I get all Sundays between two dates in Ruby?.

这个问题非常类似于我如何在Ruby中得到两个约会之间的所有星期天。

Get all days between this dates and select the days, which weekday number is 1 or 2. Sunday is the first weekday (= 0).

在这个日期之间找一天的时间，选择工作日的天数为1或2。星期天是第一个工作日。

require 'date'

start_date = DateTime.parse('2013-06-01')
end_date = DateTime.parse('2013-12-01')

result = (start_date..end_date).to_a.select { |d| [1,2].include?(d.wday) }

result.count

The result is 52 times.

结果是52倍。

#2

Use wday method of Date class that returns the day of week (0-6, Sunday is zero), so Mon is 1 and Tue is 2.

使用日期类的wday方法返回星期的日期(0-6，星期日为0)，因此Mon是1,Tue是2。

require 'date'
dates = [*Date.new(2014,1,1)..Date.new(2014,10,1)]
p dates.count{|d| (d.wday == 1) || (d.wday == 2) }

Result:

结果:

#=> 78

Updated

更新

To compare array and range sets:

比较数组和范围集:

require 'date'
require 'benchmark'

d1 = [*Date.new(2013,2,11)..Date.new(2013,12,25)]
d2 = Date.new(2013,2,11)..Date.new(2013,12,25)

n = 10000
Benchmark.bm do |x|
  x.report('array') { n.times do d1.count{|d| (d.wday == 1) || (d.wday == 2) }; end }
  x.report('range') { n.times do d2.count{|d| (d.wday == 1) || (d.wday == 2) }; end }
end

Result:

结果:

         user     system      total        real
array  0.405000   0.000000   0.405000 (  0.419041)
range  1.498000   0.000000   1.498000 (  1.505150)

#3

A bit more verbose using Date#monday?, Date#tuesday? and Enumerable#count:

在周一的日期上有点啰嗦?周二,日期# ?和可列举的#数:

require 'date'
start_date = Date.parse("2013-06-01")
end_date = Date.parse("2013-12-01")

(start_date..end_date).count { |d| d.monday? || d.tuesday? }
#=> 78

#4

=> (Date.parse(start_date)..Date.parse(end_date)).count{|d| d.wday == 1 || d.wday == 2 }
# 52