Average time of day?

Question

I'm writing a Rails app that will allow users to input what time of day they finish a task.

I am storing the times as Time objects, and I need a way to get the average time of day the task was completed for a user.

How can I accomplish this?

My attempt with Малъ Скрылевъ's answer

@deliveries = Delivery.all


times = Array.new
@deliveries.each do |d|
  times.push(d.time)
end
puts times # gives me [2000-01-01 06:15:00 UTC, 2000-01-01 07:18:00 UTC]
unless times.empty?
  @avg = Time.at(times.map(&:to_i).reduce(:+) / times.size)
end
puts @avg #gives me 1999-12-31 23:46:30 -0700

@RSB essentially yes. I have a database of time objects. I can easily get one. — Deekor, Apr 21 '14 at 05:28
This question explains it well http://stackoverflow.com/questions/20223656/average-array-of-times-as-strings-in-ruby — Rajdeep Singh, Apr 21 '14 at 05:29
@RSB I think that is different. Mine are actual ruby time objects — Deekor, Apr 21 '14 at 05:33
Look at my answer over here: https://stackoverflow.com/a/56451064/293280 — Joshua Pinter, Jun 04 '19 at 20:44

Малъ Скрылевъ · Answer 1 · 2014-04-22T07:59:54.943

3

Just you can use mathematic equations and statement on the Time object represented as Integer:

times = [ Time.now, Time.now ]
Time.at(times.map(&:to_i).reduce(:+) / times.size)

Examples

And the same for the specific time array:

First:

times = ["2000-01-01 08:13:00 UTC", "2000-01-01 18:14:00 UTC", "2000-01-01 16:55:00 UTC", "2000-01-01 23:53:00 UTC", "2000-01-01 00:56:00 UTC", "2000-01-01 02:57:00 UTC", "2000-01-01 00:01:00 UTC"].map {|t| Time.parse(t) }
Time.at(times.map(&:to_i).reduce(:+) / times.size)
# => 2000-01-01 13:09:51 +0300

Second:

times = ['2000-01-01 06:15:00 UTC', '2000-01-01 07:18:00 UTC'].map {|t|Time.parse(t)}
# => [2000-01-01 06:15:00 UTC, 2000-01-01 07:18:00 UTC] 
Time.at(times.map(&:to_i).reduce(:+) / times.size)
# => 2000-01-01 09:46:30 +0300

edited Apr 22 '14 at 07:59

answered Apr 21 '14 at 05:34

Малъ Скрылевъ

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`reduce(0, &:+)` can be simplified to `reduce(:+)`. – sawa Apr 21 '14 at 05:37
This seems to return the same time every time now that I've been testing it – Deekor Apr 21 '14 at 05:59
@Deekor show up the input array you have – Малъ Скрылевъ Apr 21 '14 at 06:02
@МалъСкрылевъ You have not understood my comment. – sawa Apr 21 '14 at 06:02
@sawa not quite understood =) – Малъ Скрылевъ Apr 21 '14 at 06:03
2000-01-01 08:13:00 UTC 2000-01-01 18:14:00 UTC 2000-01-01 16:55:00 UTC 2000-01-01 23:53:00 UTC 2000-01-01 00:56:00 UTC 2000-01-01 02:57:00 UTC 2000-01-01 00:01:00 UTC Are the array values. No matter what I add or take away from that it comes out to 1969-12-31 17:33:20 -0700 – Deekor Apr 21 '14 at 06:03
@Deekor see update, the average time is quite properly calculated – Малъ Скрылевъ Apr 21 '14 at 06:10
Ah that makes sense. I was leaving it an array of strings instead of an array of `Time` objects – Deekor Apr 21 '14 at 06:13
Actually no - I put one time in of 2000-01-01 06:15:00 UTC and get the avg 1999-12-31 23:15:00 -0700 – Deekor Apr 21 '14 at 06:16
Ive updated my question with what i am doing. What am I doing wrong? – Deekor Apr 21 '14 at 06:19
@Deekor please specify the array dump directly in the question – Малъ Скрылевъ Apr 21 '14 at 06:21
Ok see the comment next to the `puts` statements – Deekor Apr 21 '14 at 06:23
@Deekor I can't reproduce, please show exact dump – Малъ Скрылевъ Apr 21 '14 at 06:47
What do you mean exact dump? – Deekor Apr 21 '14 at 07:00
Like this: `2000-01-01 08:13:00 UTC 2000-01-01 18:14:00 UTC 2000-01-01 16:55:00 UTC 2000-01-01 23:53:00 UTC 2000-01-01 00:56:00 UTC 2000-01-01 02:57:00 UTC 2000-01-01 00:01:00 UTC` – Малъ Скрылевъ Apr 21 '14 at 07:01
that was the exact dump.. i only had 2 in my list that time – Deekor Apr 21 '14 at 07:22
@Deekor so you can see the result for the dump in my answer – Малъ Скрылевъ Apr 21 '14 at 11:03
@Deekor please see update for second example, I got correct result. – Малъ Скрылевъ Apr 22 '14 at 08:00

score 2 · Accepted Answer · answered Apr 21 '14 at 07:48

You can calculate avg by Time objects (they can be in different days). Something like this should work.

deliveries_at = @deliveries.map { |d| d.time.hour * 3600 + d.time.min * 60 + t.sec }
avg = deliveries_at.inject(:+) / deliveries_at.count
avg_hour = avg / 3600
avg_minute = (avg % 3600) / 60
avg_second = avg % 60

First line collect seconds-from-the-start-of-the-day for each delivery. Second line calculate average (in seconds) and last three lines turn it into hour/minute/second.

Average time of day?

2 Answers2

Examples