# Off Topic Advice Needed (Time objects) **URL:** \ **Category:** Rails\ **Created:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167 "2010-06-17T16:22:07Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/1 "2010-06-17T16:22:07Z")
I know this is a Ruby question but I’m not on any Ruby mailing lists and it’s for a Rails project (so might come under select\_time etc. 😉 ) I thought I’d try here. A user can choose integer values from select drop down boxes to predict how long an event will take. Obvious values are secs (0-59), minutes (0-59) … weeks (0-4), months (0-11) … These values are then converted to seconds and stored as decimal in the DB (I allow fractions of a second, too (tenth, hundredth, millisecond). when they are retrieved form the DB, I convert the seconds to a string format of, for example, 01:39:11 (from 5951 seconds). If fractions are used, they are just appended to the string. (non of this is elegant IMO) That’s all done in my Converter class. I am going to write a Calculator class to compare all times entered for an event and picking the closest times to how long the actual event took. So my question is, I know I can’t use a Time object but it would be really nice to know if there is something out there that could help me with this as to write my own Calculator is going to be a bit of a pain. Also, by throwing this out there, somebody might say something that I haven’t thought of doing and could totally change the way I’m doing this. CIA -Ants ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/2 "2010-06-17T16:22:45Z")
> So my question is, I know I can’t use a Time object but it would be really > nice to know if there is something out there that could help me with this as > to write my own Calculator is going to be a bit of a pain. If you have two floating point values representing seconds (and parts of) why can’t you just compare the two floating point values? What part are you stuck with? Can you give us some code with a comment on which bit you can’t do. Andy ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:27pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/3 "2010-06-17T16:27:00Z")
On 16 June 2010 15:54, Andy J. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > So my question is, I know I can’t use a Time object but it would be really > > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). I don’t have a problem with comparing floats, but I might need to find the 10 closest times to the actual event time and 4 of those times could be less than the actual event time and 6 could be higher. I don’t mind rolling my own and am quite looking forward to it, but I don’t want to re-invent the proverbial wheel. FWIW, here’s the conversion code to convert integer values to their respective seconds. ``` @@time_constants = {:years => YEAR, :months => MONTH, :weeks => WEEK, :days => DAY, :hours => HOUR, :mins => MIN } def to_decimal(time_units={}) raise ArgumentError if time_units.empty? time_units.each_pair do |key, value| ## skip seconds and fractions thereof next unless @@time_constants.has_key?(key) ## convert integer time units into seconds @decimal_time += @@time_constants[key] * value end ## whack on the seconds @decimal_time += time_units[:secs] if time_units.has_key?(:secs) ## need validation (can't have hundtedth without tenth, for ``` example) fraction = ‘’ fraction = ‘.’ + time\_units[:tenth].to\_s if time\_units.has\_key?(:tenth) fraction \<\< time\_units[:hundredth].to\_s if time\_units.has\_key?(:hundredth) fraction \<\< time\_units[:millisecond].to\_s if time\_units.has\_key?(:millisecond) ``` ## concat fraction string to @decimal_time, convert to float for ``` DB @decimal\_time = (@decimal\_time.to\_s \<\< fraction).to\_f end ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:34pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/4 "2010-06-17T16:34:42Z")
On 16 June 2010 15:51, Ants P. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I don’t have a problem with comparing floats, but I might need to find the > 10 closest times to the actual event time and 4 of those times could be less > than the actual event time and 6 could be higher. As a starting point, IIWM I would: - Get the ten times either side (so I have twenty objects). - Calculate the difference of how far each is from the event (ignoring sign) - Order the twenty by the difference - Take the first ten of them. With a bit of thought this could all be done in SQL… possibly with a couple of sub-queries. But it could certainly be stepped through in Ruby very easily. ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:35pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/5 "2010-06-17T16:35:19Z")
> than the actual event time and 6 could be higher. > > I don’t mind rolling my own and am quite looking forward to it, but I don’t > want to re-invent the proverbial wheel. This seems a fairly simple wheel to be worried about re-inventing though (or even to look forward to). OK, so you have an array of times. You sort through them based on: (predicted\_time - actual\_time).abs and pick the smallest 10 items. Cheers, Andy ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:35pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/6 "2010-06-17T16:35:19Z")
On 16 June 2010 16:57, Michael P. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > sign) > To post to this group, send email to removed\_email\_address@domain.invalid. > To unsubscribe from this group, send email to > removed\_email\_address@domain.invalid[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > . > For more options, visit this group at > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). As I have said before, I have no problems with all of that but thanks for the suggestions. Things do get a bit more complicated with the Calculator, though and I was only looking to make sure I wasn’t wasting my time when there was something already out there. I’ll just press on. Again, thanks for your time. ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 5:23pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/7 "2010-06-17T17:23:26Z")
On 16 June 2010 18:07, Michael P. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > [http://snippets.dzone.com/posts/show/1137](http://snippets.dzone.com/posts/show/1137) > > Of course, ignore me if there’s some critical reason they _must_ be > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). Not to worry about this as I’m happy where I’m going. Logically it’s not a huge problem, getting it Rubyish might be 😉 Long time Perl programmer. Thanks for the links, I’d already seen the second link. Thanks for the bit about the fractions, it’s given me something to think about but from what I can see, they will still have to be tacked on to the decimal. The decimals were done the way you suggested but now they’re just in a loop (more flexible) as time\_units may well be added in the future. I don’t want to labour on this so I’ll just do what I was going to do. Again, thanks. ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 17, 2010, 4:51pm UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/8 "2010-06-17T16:51:47Z")
On 16 June 2010 16:45, Ants P. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > As I have said before, I have no problems with all of that but thanks for > the suggestions. To be honest, I don’t really understand what you’re asking for help with. If you can state your position in different terms, because what you’ve said so far obviously hasn’t clicked with anyone (or at least we’ve clicked the same, wrong, way! 😉 Feeling around in the dark a little: [http://snippets.dzone.com/posts/show/1137](http://snippets.dzone.com/posts/show/1137) [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/170729](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/170729) The code you posted does look a little smelly. I don’t know why you’re turning your numbers into strings and then back into numbers again. For instance, where you say " ## need validation (can’t have hundtedth without tenth, for example)", I think you could ignore if you just approach adding up the seconds differently. So for instance if : time\_units = {:seconds =\> 22, :hundredths =\> 0, :milliseconds =\> 8} you can just do the arithmetic: fraction = 0 fraction += time\_units[:tenths] \* .1 if time\_units.has\_key?(:tenths) fraction += time\_units[:hundredths] \* .01 if time\_units.has\_key?(:hundredths) fraction += time\_units[:milliseconds] \*.001 if time\_units.has\_key?(:milliseconds) should result in 0.008 Frankly, stuff the fraction variable. Treat @decimal\_time the same: @decimal\_time += time\_units[:seconds] if time\_units.has\_key?(:seconds) @decimal\_time += time\_units[:minutes] \* 60 if time\_units.has\_key?(:minutes) @decimal\_time += time\_units[:hours] \* 3600 if time\_units.has\_key?(:hours) @decimal\_time += time\_units[:milliseconds] \*.001 if time\_units.has\_key?(:milliseconds) etc… Of course, ignore me if there’s some critical reason they _must_ be strings! 🙂 ---
**Author:** ![Ants\_P](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/6de8d8/32.png) [@Ants\_P](https://www.ruby-forum.com/u/Ants_P)\ **Post date:** [June 18, 2010, 2:50am UTC](https://www.ruby-forum.com/t/off-topic-advice-needed-time-objects/190167/9 "2010-06-18T02:50:40Z")
Ants P. wrote: > I know this is a Ruby question but I’m not on any Ruby mailing lists Then get on one (perhaps ruby-talk) and ask there. Don’t make lazy excuses for asking off-topic questions. > and > it’s for a Rails project (so might come under select\_time etc. 😉 ) That may be a better reason to ask here. > I > thought I’d try here. I’ll look at your question when I have a little more time, but please remember that “because I couldn’t bother to join the appropriate list” is not a valid reason for posting off-topic questions. 🙂 ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid