Create a new hash from an existing table

rubyonrails-talk
1

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

2

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

3

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.

4

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.

5

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

Colin