27 files changed, 76 insertions, 9 deletions
diff --git a/railties/doc/guides/source/finders.txt b/railties/doc/guides/source/finders.txt
index e81fa23e3a..a86191aaf4 100644
--- a/railties/doc/guides/source/finders.txt
+++ b/railties/doc/guides/source/finders.txt
@@ -183,7 +183,17 @@ SELECT * FROM clients LIMIT 5, 5
 
 == Group
 
-TODO
+The group option for find is useful, for example, if you want to find a collection of the dates orders were created on. We could use the option in this context:
+
+[source, ruby]
+Order.find(:all, :group => "date(created_at)", :order => "created_at")
+
+And this will give us a single Order object for each date that we have orders in our database. 
+
+The SQL that would be executed would be something like this:
+
+[source, sql]
+SELECT * FROM `orders` GROUP BY date(created_at)
 
 == Read Only
 
@@ -203,7 +213,7 @@ client.save
 
 If you're wanting to stop race conditions for a specific record, say for example you're incrementing a single field for a record you can use the lock option to ensure that the record is updated correctly. It's recommended this be used inside a transaction.
 
-[source, Ruby]
+[source, ruby]
 Topic.transaction do
   t = Topic.find(params[:id], :lock => true)
   t.increment!(:views)
@@ -233,7 +243,7 @@ This query is more efficent, but there's a gotcha. If you have a client who does
 
 When using eager loading you can specify conditions for the columns of the tables inside the eager loading to get back a smaller subset. If, for example, you want to find a client and all their orders within the last two weeks you could use eager loading with conditions for this:
 
-[source, Ruby]
+[source, ruby]
 
 Client.find(:first, :include => "orders", :conditions => ["orders.created_at >= ? AND orders.created_at <= ?", Time.now - 2.weeks, Time.now])
 
@@ -368,22 +378,76 @@ Client.exists?(:conditions => "first_name = 'Ryan'")
 
 == Calculations
 
-=== Count
-
-If you want to see how many records are in your models table you could call `Client.count` and that will return the number. If you want to be more specific and find all the clients with their age present in the database you can use `Client.count(:age)`.
+This section uses count as an example method in this preamble, but the options described apply to all sub-sections.
 
 `count` takes conditions much in the same way `exists?` does:
 
 [source, ruby]
 Client.count(:conditions => "first_name = 'Ryan'")
 
+Which will execute:
+
 [source, sql]
 SELECT count(*) AS count_all FROM `clients` WHERE (first_name = 1) 
 
-== With Scope
+You can also use `include` or `joins` for this to do something a little more complex:
+
+[source, ruby]
+Client.count(:conditions => "clients.first_name = 'Ryan' AND orders.status = 'received'", :include => "orders")
+
+Which will execute:
+
+[source, sql]
+SELECT count(DISTINCT `clients`.id) AS count_all FROM `clients` LEFT OUTER JOIN `orders` ON orders.client_id = client.id WHERE (clients.first_name = 'name' AND orders.status = 'received') 
+
+We specify `clients.first_name` just in case one of our join tables has a field also called `first_name` and we do `orders.status` because that's the name of our join table.
+
+
+=== Count
+
+If you want to see how many records are in your model's table you could call `Client.count` and that will return the number. If you want to be more specific and find all the clients with their age present in the database you can use `Client.count(:age)`.
+
+For options, please see the parent section, Calculations.
+
+=== Average
+
+If you want to see the average of a certain number in one of your tables you can call the `average` method on the class that relates to the table. This method call will look something like this:
+
+[source, ruby]
+Client.average("orders_count")
+
+This will return a number (possibly a floating point number such as 3.14159265) representing the average of the fields.
+
+For options, please see the parent section, <<_calculations, Calculations>>
+
+=== Minimum
+
+If you want to find the minimum value of a field in your table you can call the `minimum` method on the class that relates to the table. This method call will look something like this:
+
+[source, ruby]
+Client.minimum("age")
+
+For options, please see the parent section, <<_calculations, Calculations>>
+
+=== Maximum
+
+If you want to find the maximum value of a field in your table you can call the `maximum` method on the class that relates to the table. This method call will look something like this:
+
+[source, ruby]
+Client.maximum("age")
+
+For options, please see the parent section, <<_calculations, Calculations>>
+
+
+=== Sum
+
+If you want to find the sum of a field for all records in your table you can call the `sum` method on the class that relates to the table. This method call will look something like this:
+
+[source, ruby]
+Client.sum("orders_count")
+
+For options, please see the parent section,  <<_calculations, Calculations>>
 
-TODO 
-  
 == Credits
 
 Thanks to Ryan Bates for his awesome screencast on named scope #108. The information within the named scope section is intentionally similar to it, and without the cast may have not been possible.
@@ -419,3 +483,6 @@ Thanks to Mike Gunderloy for his tips on creating this guide.
 
 === Tuesday, 21 October 2008
 1. Extended named scope guide by adding :include and :joins and find sub-sections.
+
+=== Wednesday, 22 October 2008
+1. Completed calculations section.
diff --git a/railties/doc/guides/source/icons/README b/railties/doc/guides/source/images/icons/README
index f12b2a730c..f12b2a730c 100644
--- a/railties/doc/guides/source/icons/README
+++ b/railties/doc/guides/source/images/icons/README
diff --git a/railties/doc/guides/source/icons/callouts/1.png b/railties/doc/guides/source/images/icons/callouts/1.png
index 7d473430b7..7d473430b7 100644
--- a/railties/doc/guides/source/icons/callouts/1.png
+++ b/railties/doc/guides/source/images/icons/callouts/1.png
diff --git a/railties/doc/guides/source/icons/callouts/10.png b/railties/doc/guides/source/images/icons/callouts/10.png
index 997bbc8246..997bbc8246 100644
--- a/railties/doc/guides/source/icons/callouts/10.png
+++ b/railties/doc/guides/source/images/icons/callouts/10.png
diff --git a/railties/doc/guides/source/icons/callouts/11.png b/railties/doc/guides/source/images/icons/callouts/11.png
index ce47dac3f5..ce47dac3f5 100644
--- a/railties/doc/guides/source/icons/callouts/11.png
+++ b/railties/doc/guides/source/images/icons/callouts/11.png
diff --git a/railties/doc/guides/source/icons/callouts/12.png b/railties/doc/guides/source/images/icons/callouts/12.png
index 31daf4e2f2..31daf4e2f2 100644
--- a/railties/doc/guides/source/icons/callouts/12.png
+++ b/railties/doc/guides/source/images/icons/callouts/12.png
diff --git a/railties/doc/guides/source/icons/callouts/13.png b/railties/doc/guides/source/images/icons/callouts/13.png
index 14021a89c2..14021a89c2 100644
--- a/railties/doc/guides/source/icons/callouts/13.png
+++ b/railties/doc/guides/source/images/icons/callouts/13.png
diff --git a/railties/doc/guides/source/icons/callouts/14.png b/railties/doc/guides/source/images/icons/callouts/14.png
index 64014b75fe..64014b75fe 100644
--- a/railties/doc/guides/source/icons/callouts/14.png
+++ b/railties/doc/guides/source/images/icons/callouts/14.png
diff --git a/railties/doc/guides/source/icons/callouts/15.png b/railties/doc/guides/source/images/icons/callouts/15.png
index 0d65765fcf..0d65765fcf 100644
--- a/railties/doc/guides/source/icons/callouts/15.png
+++ b/railties/doc/guides/source/images/icons/callouts/15.png
diff --git a/railties/doc/guides/source/icons/callouts/2.png b/railties/doc/guides/source/images/icons/callouts/2.png
index 5d09341b2f..5d09341b2f 100644
--- a/railties/doc/guides/source/icons/callouts/2.png
+++ b/railties/doc/guides/source/images/icons/callouts/2.png
diff --git a/railties/doc/guides/source/icons/callouts/3.png b/railties/doc/guides/source/images/icons/callouts/3.png
index ef7b700471..ef7b700471 100644
--- a/railties/doc/guides/source/icons/callouts/3.png
+++ b/railties/doc/guides/source/images/icons/callouts/3.png
diff --git a/railties/doc/guides/source/icons/callouts/4.png b/railties/doc/guides/source/images/icons/callouts/4.png
index adb8364eb5..adb8364eb5 100644
--- a/railties/doc/guides/source/icons/callouts/4.png
+++ b/railties/doc/guides/source/images/icons/callouts/4.png
diff --git a/railties/doc/guides/source/icons/callouts/5.png b/railties/doc/guides/source/images/icons/callouts/5.png
index 4d7eb46002..4d7eb46002 100644
--- a/railties/doc/guides/source/icons/callouts/5.png
+++ b/railties/doc/guides/source/images/icons/callouts/5.png
diff --git a/railties/doc/guides/source/icons/callouts/6.png b/railties/doc/guides/source/images/icons/callouts/6.png
index 0ba694af6c..0ba694af6c 100644
--- a/railties/doc/guides/source/icons/callouts/6.png
+++ b/railties/doc/guides/source/images/icons/callouts/6.png
diff --git a/railties/doc/guides/source/icons/callouts/7.png b/railties/doc/guides/source/images/icons/callouts/7.png
index 472e96f8ac..472e96f8ac 100644
--- a/railties/doc/guides/source/icons/callouts/7.png
+++ b/railties/doc/guides/source/images/icons/callouts/7.png
diff --git a/railties/doc/guides/source/icons/callouts/8.png b/railties/doc/guides/source/images/icons/callouts/8.png
index 5e60973c21..5e60973c21 100644
--- a/railties/doc/guides/source/icons/callouts/8.png
+++ b/railties/doc/guides/source/images/icons/callouts/8.png
diff --git a/railties/doc/guides/source/icons/callouts/9.png b/railties/doc/guides/source/images/icons/callouts/9.png
index a0676d26cc..a0676d26cc 100644
--- a/railties/doc/guides/source/icons/callouts/9.png
+++ b/railties/doc/guides/source/images/icons/callouts/9.png
diff --git a/railties/doc/guides/source/icons/caution.png b/railties/doc/guides/source/images/icons/caution.png
index cb9d5ea0df..cb9d5ea0df 100644
--- a/railties/doc/guides/source/icons/caution.png
+++ b/railties/doc/guides/source/images/icons/caution.png
diff --git a/railties/doc/guides/source/icons/example.png b/railties/doc/guides/source/images/icons/example.png
index bba1c0010d..bba1c0010d 100644
--- a/railties/doc/guides/source/icons/example.png
+++ b/railties/doc/guides/source/images/icons/example.png
diff --git a/railties/doc/guides/source/icons/home.png b/railties/doc/guides/source/images/icons/home.png
index 37a5231bac..37a5231bac 100644
--- a/railties/doc/guides/source/icons/home.png
+++ b/railties/doc/guides/source/images/icons/home.png
diff --git a/railties/doc/guides/source/icons/important.png b/railties/doc/guides/source/images/icons/important.png
index 1096c23295..1096c23295 100644
--- a/railties/doc/guides/source/icons/important.png
+++ b/railties/doc/guides/source/images/icons/important.png
diff --git a/railties/doc/guides/source/icons/next.png b/railties/doc/guides/source/images/icons/next.png
index 64e126bdda..64e126bdda 100644
--- a/railties/doc/guides/source/icons/next.png
+++ b/railties/doc/guides/source/images/icons/next.png
diff --git a/railties/doc/guides/source/icons/note.png b/railties/doc/guides/source/images/icons/note.png
index 841820f7c4..841820f7c4 100644
--- a/railties/doc/guides/source/icons/note.png
+++ b/railties/doc/guides/source/images/icons/note.png
diff --git a/railties/doc/guides/source/icons/prev.png b/railties/doc/guides/source/images/icons/prev.png
index 3e8f12fe24..3e8f12fe24 100644
--- a/railties/doc/guides/source/icons/prev.png
+++ b/railties/doc/guides/source/images/icons/prev.png
diff --git a/railties/doc/guides/source/icons/tip.png b/railties/doc/guides/source/images/icons/tip.png
index a3a029d898..a3a029d898 100644
--- a/railties/doc/guides/source/icons/tip.png
+++ b/railties/doc/guides/source/images/icons/tip.png
diff --git a/railties/doc/guides/source/icons/up.png b/railties/doc/guides/source/images/icons/up.png
index 2db1ce62fa..2db1ce62fa 100644
--- a/railties/doc/guides/source/icons/up.png
+++ b/railties/doc/guides/source/images/icons/up.png
diff --git a/railties/doc/guides/source/icons/warning.png b/railties/doc/guides/source/images/icons/warning.png
index 0b0c419df2..0b0c419df2 100644
--- a/railties/doc/guides/source/icons/warning.png
+++ b/railties/doc/guides/source/images/icons/warning.png