MESSAGE
| DATE | 2011-05-15 |
| FROM | Ruben Safir
|
| SUBJECT | Re: [NYLXS - HANGOUT] C++ Workshop - Notes
|
We will be creatinf a standard deviation algorithm tonight, so try to
make it.
Ruben
On Mon, May 09, 2011 at 07:06:47PM -0400, Ruben Safir wrote:
> Within the workshop we have played with a rudimentary statistical
> module within out test_del.cpp program. It's been tested fairly
> rigerously and i think it is probably useful to remove the module from
> the parent program and to put it into it's own header file. As such,
> this is the program file, which i want to review for a minute
>
> * =====================================================================================
> *
> * Filename: stats.h
> *
> * Description: simple distribution execise
> *
> * Version: 1.0
> * Created: 04/15/2011 06:12:42 PM
> * Revision: none
> * Compiler: gcc
> *
> * Author: Ruben Safir,
> * Company:
> *
> * =====================================================================================
> */
> #ifndef STATS_H
> #define STATS_H
> #include
> #include
> #include
> #include
> #include
> #include "linklist.h"
>
> /*
> * =====================================================================================
> * Class: Distribution
> * Description: Keeps Track of Distribution of 6's (or anything else)
> * in a series of List
> * =====================================================================================
> */
>
>
> namespace stats{
>
> template
> class Distribution {
> template friend std::ostream & operator<<(std::ostream &, const
> Distribution&);
> public:
> /* ==================== LIFECYCLE
> * ======================================= */
> Distribution (T descr, int occurances = 0);
> Distribution():freq(NULL),occurances(NULL){};
> // Distribution ( const Distribution &other ); /* copy
> // constructor */
> // ~Distribution (); /*
> // destructor */
> /* ==================== ACCESSORS
> * ======================================= */
> T description()const{ return freq;}
> int population()const { return occurances; }
> /* ==================== MUTATORS
> * ======================================= */
> void increase_occ(){ ++occurances; std::cout <<
> "description " << freq << " occurances " << occurances << std::endl; }
> void descrease_occ(){ --occurances; }
> /* ==================== OPERATORS
> * ======================================= */
> //Distribution& operator = ( const Distribution &other
> //); /* assignment operator */
> int operator()(){
> return freq;
> }
> bool operator==(Distribution &tmp){
> if(this->freq == tmp.freq)
> return true;
> return false;
> }
>
> bool operator<(Distribution &tmp){
> if(freq < tmp.freq)
> return true;
> return false;
> }
> chainlist::List< stats::Distribution > * tally; //a list of
> distribution talleys
>
>
>
> protected:
> /* ==================== DATA MEMBERS
> * ======================================= */
> private:
> /* ==================== DATA MEMBERS
> * ======================================= */
> T freq; //description of how many times found in a List
> int occurances; //description of how many times a
> frequency was found in a list
> }; /* ----- end of class Distribution ----- */
>
>
> template
> std::ostream & operator << ( std::ostream & os, const Distribution &
> obj )
> {
> T desc = obj.description();
> int pop = obj.population();
> os << "The Identification of " << desc << " was seen " << pop ;
> return os;
> } /* ----- end of function operator << ----- */
>
> template
> Distribution::Distribution(T descr, int occ): occurances(occ){
> freq = descr;
> }
>
>
> /* Routine to go though a single list and add it to an existing
> * distribution table */
> template
> void mount_individual_data_point(chainlist::List * tabulate,
> chainlist::List > * table);
>
> /* Routine to find all the occurances of a type in a list of lists */
> template
> void take_tally(chainlist::List
> *,chainlist::List > *);
>
>
>
>
>
>
> template
> void take_tally(chainlist::List * tabulate,
> chainlist::List > * table){
> for(tabulate->cursor()=tabulate->front();tabulate->cursor() !=
> tabulate->endd(); tabulate->cursor( tabulate->cursor()->next() ) ){
> //build distribution list
> mount_individual_data_point(tabulate, table);
> }
> //we are at the end of tabulate
> mount_individual_data_point(tabulate, table);
> table->sort(*table);
> }
>
> template
> void mount_individual_data_point(chainlist::List * tabulate,
> chainlist::List > * table){
> int val;
> stats::Distribution * j;
> val = *(tabulate->cursor()->value()); //get a value
> table->cursor()= table->front(); //check to see if the distribution
> list exists
> if(!table->cursor()){ // if not add a distribution table to the List
> of distributions
> j = new stats::Distribution (val);
> table->insert(*j ); //now we have at least one
> delete j;
> j=table->cursor()->value();//and increased its population
> j->increase_occ();
> }else{
> //otherwise search for a distribution node described as value
> table->find_value(val);
> if( table->cursor() ){
> j=table->cursor()->value();//and increase its population
> j->increase_occ();
> }else{//otherwise add a new node
> j = new stats::Distribution (val);
> table->insert( *j ); //now we have one for that value
> delete j;
> j=table->cursor()->value();//and increased its population
> j->increase_occ();
> }
> }
> }
>
>
>
> }
> #endif /* STATS_H */
>
> In total it is about `50 lines in the namespace stats
>
> The class Distribution has 2 basic data members, freq, which is an
> object of type T according to the template, generally a specific data
> point among a set of data, and occurances of type int which holds how
> many times data point freq occurs within a set of data.
>
> so if you have a set of data, chars for example
>
> { a, f, d, r ,t w, d, i, d, k, l, g }
>
> you can create a single distribution object who might hold, for example,
> the letter d and the occurances of d as 3 (there are 3 'd''s in our set.
>
>
> There is a member function to class Distribution called take_tally
> defined as follows
>
> template
> void take_tally(chainlist::List *,chainlist::List > *);
>
> it takes as arguments a pointer to one of our custom lists within
> the chainlist namespace. That needs to have a set of nodes with values
> of type T in each node. That list will be searched for values in order
> to record their frequencies of occurances, unique value recorded in a
> Distribution object, of which a list of those will be stored in the
> chainlist::List of type Distribution which is being passed as the second
> argument, each Distribution Object a value of a node.
>
> The member function mount_individual_data_point actually constructs and
> builds a chainlist::List adding new nodes as needed, and
> increasing the occurance counts for each unique data type.
>
> As it stands, the module is useful, but not nearly as useful as it can
> be. Seperating out this namespace will allow us to greatly develop our
> statistical analysis capabilities of Lists in a uniform API
>
> Ruben
>
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