How to get middle period of 2 date periods in ruby?

Question

c should be inner period of 2 periods. How to get it in most elegant way?

a1=Date.current
a2=Date.current + 2.months

b1=Date.current + 1.month
b2=Date.current + 3.months

c=???

c.should_be [Date.current + 1.month, Date.current + 2.months]

@Sergio you don't want to see current implementation. your eyes will bleed. — Arnis Lapsa, May 24 '12 at 08:13
"what have you tried" isn't appropriate for general questions like this imho — pguardiario, May 24 '12 at 08:21
@SergioTulentsev didn't try too hard. just got it working. but I'm not looking for any implementation, looking for elegant one. usually knowing how to do things best takes years of experience and i lack them atm. — Arnis Lapsa, May 24 '12 at 08:29

score 2 · Accepted Answer · edited May 23 '17 at 12:28

2

Hurried implementation:

xs = (a1..a2).to_a & (b1..b2).to_a
(xs.first..xs.last)
# => Sun, 24 Jun 2012..Tue, 24 Jul 2012

There is nothing special about a range of dates. So search "range intersection" to do it more efficiently (for example here). Now you can write:

(a1..a2) & (b1..b2)

edited May 23 '17 at 12:28

Community

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1

answered May 24 '12 at 08:14

tokland

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yap... intersection is the word i couldn't remember :) – Arnis Lapsa May 24 '12 at 08:16
Be careful that neither of your dates are really Time objects, or your range will have one element for every second between the two ;-) – Pavling May 24 '12 at 12:41

score 0 · Answer 2 · answered May 24 '12 at 08:23

0

d= [a1, a2, b1, b2]
[*1..d.length/ 2].map do |dt| 
    d.shift(2) 
end.map do |dx| 
    Date.current+ (dx[1]- dx[0]) 
end

[Sun, 24 Jun 2012, Tue, 24 Jul 2012]

answered May 24 '12 at 08:23

nurettin

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How to get middle period of 2 date periods in ruby?

2 Answers2