Array of date by each week

Question

I have two dates, example :

date1 = "4-02-2017".to_date
date2 = "4-02-2017".to_date + 29

I try to get array of date by each week with this :

(date1..date2).select{|x| Date::DAYNAMES[x.wday] == Date::DAYNAMES[date1.wday] }

Rersult :

[2017年2月04日, 
 2017年2月11日,
 2017年2月18日, 
 2017年2月25日,
 2017年3月04日]

Is there a better way to solve the case other than the way as above?

Answer 1

There's no reason to look up the day's name in the DAYNAMES array. You already have the wday values, so you can just compare those directly.

I.e. if

Date::DAYNAMES[x] == Date::DAYNAMES[y]

it follows that

x == y

so:

(date1..date2).select { |date| date.wday == date1.wday }

Or, simpler, you can specify a step for the range and just skip one week at a time:

(date1..date2).step(7).to_a

Now, a week is typically 7 days long, but there have been a few cases of nations choosing to officially move to the other side of the international dateline, causing a week to not be 7 days long in their calendar. It's rare of course, but something to be aware of.