Creating an array by reusing code

Hi
   I have
all_req = OnRequest.find(:all, :conditions => [status_id = ?',6])

   Now i need to create an array of size 12 containing record counts for
month January to December like [recordcountjanuary,recordcountfeb,....]
So for the first month january I tried like

all_req.select do |r|
r.created_at.mon == 1
end
       What i need is reuse the above code I have placed it in a
function But there I have to call it 12 times .How can i avoid this?

Thanks in advance
Sijo

···

--
Posted via http://www.ruby-forum.com/.

Maybe this helps (untested):

recordcount = (1..12).map do |month|
   all_req.select {|r| r.created_at.mon == month}.size
end

Although this does 12 passes through all_req. BTW, if you need the
count you need to check the size of the select. Maybe another approach
could be using a hash:

recordcount = Hash.new(0)
all_req.each do |r|
   recordcount[r.created_at.mon] += 1
end

Hope this helps,

Jesus.

···

On Wed, Mar 25, 2009 at 11:42 AM, Sijo Kg <sijo@maxxion.com> wrote:

Hi
I have
all_req = OnRequest.find(:all, :conditions => [status_id = ?',6])

Now i need to create an array of size 12 containing record counts for
month January to December like [recordcountjanuary,recordcountfeb,....]
So for the first month january I tried like

all_req.select do |r|
r.created_at.mon == 1
end
What i need is reuse the above code I have placed it in a
function But there I have to call it 12 times .How can i avoid this?

Let's build this up a step at a time...

monthly_counts = (1..12).map do |month|
  # call your function here, passing in the month
end

Depending on the scope of all_req, it may just be easier to inline the
function as follows:

monthly_counts = (1..12).map do |month|
  all_req.select {|r| r.created_at.mon == month }.size
end

However, this is inefficient. We have to make 12 passes over the
all_req collection.
You can, instead use Enumerable#group_by:

all_req.group_by {|r| r.created_at.mon }

which will return a hash of items keyed by the month. Getting counts
from this is simply a matter of using #map. I'll leave this as an
exercise :slight_smile:

Now, having said all that, the most efficient way to do this is
probably to use a group_by clause in your finder. Again, left as an
exercise (mostly 'cos i don't know AR :slight_smile:

solidarity,
lasitha

···

On Wed, Mar 25, 2009 at 4:12 PM, Sijo Kg <sijo@maxxion.com> wrote:

[...]
Now i need to create an array of size 12 containing record counts for
month January to December like [recordcountjanuary,recordcountfeb,....]
So for the first month january I tried like

all_req.select do |r|
r.created_at.mon == 1
end
What i need is reuse the above code I have placed it in a
function But there I have to call it 12 times .How can i avoid this?

However, this is inefficient. We have to make 12 passes over the
all_req collection.
You can, instead use Enumerable#group_by:

all_req.group_by {|r| r.created_at.mon }

which will return a hash of items keyed by the month. Getting counts
from this is simply a matter of using #map. I'll leave this as an
exercise :slight_smile:

Or create a counter Hash and loop once:

counts = Hash.new 0
all_req.each {|r| counts[r.created_at.mon] += 1}

Now, having said all that, the most efficient way to do this is
probably to use a group_by clause in your finder. Again, left as an
exercise (mostly 'cos i don't know AR :slight_smile:

Yep, the database solution is probably the best.

Cheers

robert

···

2009/3/25 lasitha <lasitha.ranatunga@gmail.com>:

--
remember.guy do |as, often| as.you_can - without end