similar to: Theoretical: Should models be subclasses of AR or mix it in?

Dear R experts, I would really appreciate if you had an idea on how to use more efficiently the aggregate method: More specifically, I would like to calculate the mean of certain values on a data frame,? grouped by various attributes, and then create a new column in the data frame that will have the corresponding mean for every row. I attach part of my code: matchMean <-

Consider: > x <- matrix(1:6, 2,3) > rownames(x) <- c("ID1", "ID2") > colnames(x) <- c("Attr1", "Attr2", "Attr3") > x Attr1 Attr2 Attr3 ID1 1 3 5 ID2 2 4 6 > write.csv(x,file="x.csv") "","Attr1","Attr2","Attr3" "ID1",1,3,5

I find myself writing the following frequently: r = MyActiveRecord.where(:attr1 => cond1, :attr2 => cond2, ...) r.exists? ? r.first : r.create ... which has the effect of returning an instance of MyActiveRecord if all the conditions are met, or creating one if it doesn''t. A variant of this: c = MyActiveRecord.new(:attr1 => val1, :attr2 => val2, ...) r =

Hi, I have 100000 units with 10 attributes (attr1, attr2, attr3, etc...) For instance: unit attr1 attr2 attr3 ... 1 a ww 12 2 a re 11 3 b ww 09 4 c yt 02 5 a qw 02 ... I'd like to answer to the question: a) what are the most frequent combinations of attributes? b) How could I describe the relations

Ok, So, I''ve got two data tables associated through a foreign key. class Child < ActiveRecord::Base belongs_to :parent, :class => Parent, :foreign_key => "parent_id" # also has attr1, attr2 end class Parent < ActiveRecord::Base has_many :children, :class => Child, :foreign_key => "parent_id" end So, I''m trying to build the new/edit

In R-devel (svn 49628) and back to at least R 2.7.0 we get inconsistent results when attempting to attach attributes to a variable with the value NULL. If we use attributes<- it finishes but changes the value to list(). > a<-NULL > attributes(a)<-list(attr1="First attribute", attr2=2+2i) > a list() attr(,"attr1") [1] "First

Hi, Whenever I restart mongrel on my production server, the first request in my browser always fails, I get this error: Processing Base#index (for 83.xx.xx.xx at 2006-09-03 16:08:47) [GET] Session ID: f1918346d193e19a70c3230286e5ce1a Parameters: {} TypeError (superclass mismatch for class Stats): /app/models/stats.rb:1 stats.rb:1 just contains a normal A/R line: class Stats <

When I use rbind() or rbind.data.frame() to add a row to an existing dataframe, it appears that attributes for the column of type "factor" are dropped. See the sample example below to reproduce the problem. Please suggest How I can fix this. Thanks, Sammy a=c("Male", "Male", "Female", "Male") b=c(1,2,3,4) c=c("great", "bad",

Hi, I am a Rails noob. Suppose you have: --- class Animal < ActiveRecord::Base end class Mammal < Animal end class Cow < Mammal end --- I provide Animal,Mammal and Cow controllers with the scaffolding, just to test and to fill up the Animal table. I can see the "type" column getting it''s value set with the class name. So far, soo good. Now, since listing Animals

Is it possible to create a database in MySQL via RMySQL? Also, is the format for the authorization field 'userName/password at databasename'? I saw an example like this somewhere in the documenation, but I haven't found the actual specification. Thanks, Barnet Wagman

I have a STI class tree. I want to set some default values (calculated values so I can''t set it in the database as defaults) on every created instance regardless of what subclass is actually instantiated. So I figured adding a after_create callback in the top class in the hierarchy should do the trick. It seems it doesn''t get called :( Code: class SuperClass <

Hello, to implement some some kind of optimistic locking, I want to build a view, where an object is displayed together with a link containing the data of the displayed object. My first try looked something like <%= object.object_discription %> <%= link_to "action", :action => "take_action", :data => object %> this won''t work because object is of

Here is my class: class Document < ActiveRecord::Base public def initialize puts "Called initialize..." super.initialize end This generates the following error: You have a nil object when you didn''t expect it! You might have expected an instance of ActiveRecord::Base. The error occured while evaluating nil.initialize WTF? Wes -- Posted via

All, There is an assertion in AWDWR that the in-memory session store is "too simplistic." However, I find myself nudged in this direction by the need to keep a non-serializable model attribute available in my session and the relative pain of implementing either a custom serialization scheme for the model in question (or a custom caching mechanism so that I can store my attribute

I want my helpers to generate paths using a superclass instead of the subclasses. Assuming I have Owner and Member that both inherit from User, rails will use the current objects class name when generating paths: Let''s say current_user is a mod: <%= link_to current_user.name, current_user %> will generate "/mod/:id". I want to force it to generate

All, I''m having a hell of a time figuring out what is going on here. I''m trying to override one of my getters so that I can format it a certain way in my form. But I can''t seem to get text_field to call the appropriate method on my object. So here''s my getter: public def FAX fax = read_attribute(:FAX) puts fax

Hello, I have a few models -- book, cd, dvd -- for which I''d like to have an abstract base superclass to hold some common stuff. That abstract class, I was thinking, would inherit from ActiveRecord. Didn''t work, though, and looking around, I found this: <http://wiki.rubyonrails.com/rails/pages/HowtoMakeAbstractModel>

All, I''m starting to see view state information creeping into my model class. For example, I have text fields in my view that need to be set a certain way depending on whether or not a checkbox is checked. And while the values of these text fields ultimately do represent database columns that are related to the backing AR object, the text_field values also represent attributes on a

Is there such a thing? I have some duplicate methods in my models, can I place them somewhere and call them in to my models, thus keeping DRY? -- Posted via http://www.ruby-forum.com/.

All, After a POST, I want to be able to redisplay a view with the data that was previously entered when my controller action notices a validation failure and calls render on the view that does the submit. Example: View x.rhtml - text field is filled in Call controller action Controller action fails validation calls render (:action => ''x'') x.rthml shows up with blank text