Create a new hash from an existing table

[edward michaels]

I have an active record Times table with a date column and an hour
column. The hours are unique but the dates can have many hours. How
would I create a hash that mapped a date key to its hours? Something
like:

hours_per_date['2/14/2012'] => ['6:00', '8:00', '11:00', '2:00']

Thanks

[Everaldo Gomes]

Hi!

Take a look at:

http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-group_by

and

http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-collect

I think they could help.

E.g:

hash = Time.all.collect { |t| [ t.date  , t.hour ] }.group_by { |date,hour| date.strftime("%-m/%-d/%Y") }

I hope it works.

Regards,

Everaldo

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[Everaldo Gomes]

On Sat, Feb 11, 2012 at 11:50 PM, Everaldo Gomes <everald...@gmail.com> wrote:

Hi!

Take a look at:

http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-group_by

and

http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-collect

I think they could help.

E.g:

hash = Time.all.collect { |t| [ t.date  , t.hour ] }.group_by { |date,hour| date.strftime("%-m/%-d/%Y") }

I forgot that after using group_by you will have to discard the date from the hash values.

[edward michaels]

Thanks, your idea did help.

if I do:

date = <some_date>
reduce = Time.where(:date => date)
hour_on_date = reduce.collect {|x| x.hour}

Now I just need to figure out how to make <some_date> a hash key which
triggers the hour_on_date array value.

On Feb 11, 8:50 pm, Everaldo Gomes <everaldo.go...@gmail.com> wrote:
> Hi!
>
> Take a look at:
>
> http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-group_by
>
> and
>
> http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-collect
>
> I think they could help.
>
> E.g:
>
> hash = Time.all.collect { |t| [ t.date  , t.hour ] }.group_by { |date,hour|
> date.strftime("%-m/%-d/%Y") }
>
> I hope it works.
>
> Regards,
> Everaldo
>

[Colin Law]

On 13 February 2012 07:00, edward michaels <mica...@gmail.com> wrote:
> Thanks, your idea did help.
>
> if I do:
>
> date = <some_date>
> reduce = Time.where(:date => date)

I think you might run into trouble using a class Time as this is
already a ruby class.

Colin