Calculating the Number of Weeks in a Year with Ruby

Calculating the number of weeks in a year with Ruby

def num_weeks(year = Date.today.year)
  Date.new(year, 12, 28).cweek # magick date!
end

long_iso_years = (2000..2400).select{|year| num_weeks(year) == 53} 

Yields the same list as wikipedia

Rails number of weeks in month

i dont know exactly what you want... But maybe you want something like this:

(Time::days_in_month(05,2010).to_f / 7)

#> 4.42857142857143

Generate a list of commercial weeks falling between 2 dates in Ruby / Rails

Thank you to those who replied t. I've finally solved the problem like this:

  campaign_weeks = []

  campaign_start_date = "2014-07-23 06:59:00" # or any date
  campaing_end_date = "2015-03-01 06:59:00" # or any date

  start_year = DateTime.parse(campaign_start_date).cwyear
  start_cweek_of_the_campaign = "%04d%02d" % [start_year, DateTime.parse(campaign_start_date).cweek]

  end_year = DateTime.parse(campaing_end_date).cwyear
  end_cweek_of_the_campaign = "%04d%02d" % [end_year, DateTime.parse(campaing_end_date).cweek]

  if start_year == end_year
    (start_cweek_of_the_campaign..end_cweek_of_the_campaign).each do |w|
      campaign_weeks << ("%04d%02d" % [start_year, w])
    end
  else
    (start_year..end_year).each do |y|
      first_cweek_number_of_the_year = (y == start_year) ? start_cweek_of_the_campaign : 1
      last_cweek_number_of_the_year = (y == end_year) ? end_cweek_of_the_campaign : DateTime.new(y, 12, 28).cweek
      (first_cweek_number_of_the_year .. last_cweek_number_of_the_year).each do |w|
        campaign_weeks << ("%04d%02d" % [y, w])
      end
    end
  end

  return campaign_weeks

Notes: 28th Dec always fall in the last cweek/iso-week of the year. last ISO week of the year is either 52 or 53.

Reference: http://en.wikipedia.org/wiki/ISO_week_date#Last_week

Got some hint from this answer: Calculating the number of weeks in a year with Ruby

Calculating the number of weeks in a month for a calendar in Rails

Ok, so some fiddling around lead me to this solution:

  def week_rows
     weeks.map {|week|
        content_tag :div, class: week_classes do
           week.map { |day| day_cell(day) }.join.html_safe
        end
     }.join.html_safe
  end

  def week_classes
     classes = ['week']
     classes << "wk_rows_4" if weeks_in_month == 4
     classes << "wk_rows_5" if weeks_in_month == 5
     classes << "wk_rows_6" if weeks_in_month == 6
     classes.empty? ? nil : classes.join(" ")
  end

  def weeks_in_month
     (0.5 + (date.end_of_month.day + date.at_beginning_of_month.wday).to_f / 7.0).round
  end

It wasn't necessary to pass in (date) as a parameter.

Given a timestamp, how to determine how many weeks ago?

If you just want to build a human-friendly string, I believe time_ago_in_words is what you are after.

https://apidock.com/rails/ActionView/Helpers/DateHelper/time_ago_in_words

Otherwise, I would resort to something like the following:

(Time.new - user.created_at) / 1.week

If you want a more elegant solution, Subtract dates in Ruby and get the difference in minutes mentions the Time Difference gem for Ruby.

e.g.

TimeDifference.between(user.created_at.to_time, Time.now).in_weeks

Week number calculation in rails

You could compare the current calendar week with Date.current.cweek (Reference) with your number.

require 'active_support/core_ext' # Already included in Rails

def calendar_week(week)
  now = Date.current
  year = now.cweek < week ? now.year : now.year + 1
  Date.commercial(year, week, 1)
end

p calendar_week(49)
# => Mon, 02 Dec 2013

p calendar_week(1)
# => Mon, 30 Dec 2013 # don't know if that's the way calendar weeks are counted

p calendar_week(27)
# => Mon, 30 Jun 2014

How to calculate the current week in the month in Ruby

In order to handle the requirements you listed, I would suggest writing a helper function to get the number of the week in a month.

def get_month_week(date_or_time, start_day = :sunday)

  date = date_or_time.to_date
  week_start_format = start_day == :sunday ? '%U' : '%W'

  month_week_start = Date.new(date.year, date.month, 1)
  month_week_start_num = month_week_start.strftime(week_start_format).to_i
  month_week_start_num += 1 if month_week_start.wday > 4 # Skip first week if doesn't contain a Thursday

  month_week_index = date.strftime(week_start_format).to_i - month_week_start_num
  month_week_index + 1 # Add 1 so that first week is 1 and not 0

end

This can then just be called like so:

get_month_week(Date.today)

If you really feel like monkey-patching is something you want, you can add to the Date class:

class Date

  def month_week(start_day = :sunday)

    week_start_format = start_day == :sunday ? '%U' : '%W'

    month_week_start = Date.new(self.year, self.month, 1)
    month_week_start_num = month_week_start.strftime(week_start_format).to_i
    month_week_start_num += 1 if month_week_start.wday > 4 # Skip first week if doesn't contain a Thursday

    month_week_index = self.strftime(week_start_format).to_i - month_week_start_num
    month_week_index + 1 # Add 1 so that first week is 1 and not 0

  end

end

And this can be called on a date or time like so:

Date.today.month_week

or

Time.current.to_date.month_week

I would advise against this since it may collide with other libraries or violate least-surprise for other developers working on the project.

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