# Newbie question \> count array key?

**URL:** <https://www.ruby-forum.com/t/newbie-question-count-array-key/161250>\
**Category:** Ruby\
**Created:** [February 24, 2009, 6:57pm UTC](https://www.ruby-forum.com/t/newbie-question-count-array-key/161250 "2009-02-24T18:57:19Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![remco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/9d8465/32.png) [@remco](https://www.ruby-forum.com/u/remco)\
**Post date:** [February 24, 2009, 6:57pm UTC](https://www.ruby-forum.com/t/newbie-question-count-array-key/161250/1 "2009-02-24T18:57:19Z")

</div>

Hi,

newbie question(i guess)

a = Bookings.find(:all, :conditions =\> [3.days.ago])  
a = [id : 1, departure : ‘AMS’, arrival =\> ‘NY’],[id : 2, departure :  
‘AMS’, arrival =\> ‘BCN’],[id : 3, departure : ‘AMS’, arrival =\>  
‘BKK’],[id : 4, departure : ‘AMS’, arrival =\> ‘BKK’] ect.

The value of the key departure and arrival is dynamic based on  
table(3000 combinations) and the bookings

I want to find the bookings and count the arrival and departure(s). I  
the case of the code above, i want the following output.

departure = AMS \> total = 5  
arrival = BCN \> total = 1  
arrival = NY \> total = 1  
arrival = BKK \> total = 2

How can i do this

Grtz…remco

---

<div class="post-metadata">

**Author:** ![remco](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/9d8465/32.png) [@remco](https://www.ruby-forum.com/u/remco)\
**Post date:** [February 25, 2009, 4:46pm UTC](https://www.ruby-forum.com/t/newbie-question-count-array-key/161250/2 "2009-02-25T16:46:14Z")

</div>

Remco S. wrote:

> newbie question(i guess)
> 
> a = Bookings.find(:all, :conditions =\> [3.days.ago])  
> a = [id : 1, departure : ‘AMS’, arrival =\> ‘NY’],[id : 2, departure :  
> ‘AMS’, arrival =\> ‘BCN’],[id : 3, departure : ‘AMS’, arrival =\>  
> ‘BKK’],[id : 4, departure : ‘AMS’, arrival =\> ‘BKK’] ect.
> 
> The value of the key departure and arrival is dynamic based on  
> table(3000 combinations) and the bookings
> 
> I want to find the bookings and count the arrival and departure(s). I  
> the case of the code above, i want the following output.
> 
> departure = AMS \> total = 5  
> arrival = BCN \> total = 1  
> arrival = NY \> total = 1  
> arrival = BKK \> total = 2
> 
> How can i do this

You iterate through the rows, counting the values of interest.

Constructs you may find useful are:

(1) the ‘each’ method of the Array class (to iterate through your array)

a.each do |booking|  
p booking  
# or do something else with it  
end

(2) Hashes, especially ones which have a default value of zero

count = Hash.new(0)

count[“foo”] += 1  
count[“bar”] += 1  
count[“foo”] += 1

# after this, count = {“foo”=\>2, “bar”=\>1}

(3) the ‘each’ method of the Hash class

count.each do |key,value|  
puts “#{key}: #{value}”  
end

(4) The ‘irb’ shell, for trying these things out, or script/console if  
you are using Rails (the latter will also give you full access to your  
model classes)

$ irb  
irb(main):001:0\> count = Hash.new(0)  
=\> {}  
irb(main):002:0\> count[“foo”] += 1  
=\> 1  
irb(main):003:0\> count[“bar”] += 1  
=\> 1  
irb(main):004:0\> count[“foo”] += 1  
=\> 2  
irb(main):005:0\> count  
=\> {“foo”=\>2, “bar”=\>1}

See your favourite Ruby documentation for more details on these topics.  
If you don’t have any, then an old version of the Pickaxe book is  
browsable online for free here:  
[http://www.ruby-doc.org/docs/ProgrammingRuby/](http://www.ruby-doc.org/docs/ProgrammingRuby/)