TAsciiData

written by: lore
email: lore at newty dot de
home: www.newty.de
last updated: 25.07.00

Download Example Project

Overview

multithreaded "load ASCII-data-matrix from file" class

Important Functions

void load(const char* filename)	Loads the data-matrix. This function can only be called once in the lifetime of an instance. This is easier to implement and costs only a minimum of additional resources.
void save(const char* filename)	Saves data-matrix to file.
inline int nDS()	Query number of rows. Inline function, i.g. always use it and do not copy the value to an own variable!
inline int dim()	Query number of columns. Inline function, i.g. always use it and do not copy the value to an own variable!
const float* getRow(const int i)	Query of the i´th row. All counting starts with zero! Thus the first row is adressed by the index 0.
void calc()	Column-wise calculate statistical values which can be queried using getMeanVec(), getMinVec(), getMaxVec(), getRangeVec() and getDevVec().
void randomize(const int n)	Interchange two random rows n-times.
void sort(const int col)	Sort rows according to the values of the specified column col.

Details

The number of columns and rows is detected automatically. The first non-empty row determines the number of columns for all other rows.
Whitespaces and comments are always ignored when reading a file. Comments must start at the begin of a line. The comment introducing characters are %, # and *. They can be changed by editing the function bool IsComment(const char c) in fileUtil.cpp.
load(...), save(...) and calc() run in an additional thread when a parent, font and resource id is supllied in the constructor. The resource id must correspond to a simple dialog resource definition in the resource file.
Important: The destructor is private, i.g. you have to call release() instead. See the header to find out why.
Important: It is the philosophy to throw an exception in case of errors or non-permissibility of an action even if it would be possible to perform a default or neutral action. Exceptions are of type TErrText. This is a struct containing only a character-array and allows us to pass/copy a whoole array and not just the pointer to its first element.
You find details about the time-series functionality in the header-file asciidata.h.

How to Use

The following code is an excerpt from the project´s file main.cpp and shows how to use the class TAsciiData. There is only one function CmDataDemo() which is called when the user hits the menu-item Data-Demo.

   /****************************************************/
   //
   //  usage of "load ASCII data from file"-class
   //


#include "asciidata.h"


/***********************************************************************************************************/
// load a file named "test.dat" and do some things with it ...
void mainWnd::CmDataDemo()
{
   // a) create TAsciiData object
   TAsciiData* data = new TAsciiData(this, font, IDD_DIALOG);

   // b) read data - note: reading can cause an exception. thus encapsulate all in a try-block
   try
   {
      data->load("test.dat");       // load data - this file must exist
      data->calc();                 // calculate statistical values
   }
   catch(TErrText err)
   {
      MessageBox(err.szErrText, "error loading test.dat", MB_OK | MB_ICONERROR);
   }


  // c) check success
   if(data->dim() == 0 || data->nDS() == 0)  // if data-matrix has zero rows or columns -> ...
   {
      data->release();     // ... release it again
      return;
   }


  // d) do something with the data - note: in a try-block cause save() can throw an exception
   try
   {
     // how to access the data - example: calculate the sum of each column
     // IMPORTANT: all countig starts up with zero. thus the first row has the index 0.
      double* sum = new double[data->dim()];               // allocate memory for the sums

      for(int i=0;i<data->nDS();i++)                     // over all rows
      {
         const float* row = data->getRow(i);             // get pointer to i-th´s row

         for(int j=0;j<data->dim();j++)                  // over of columns of the actual row ...
            sum[j]+=row[j];                                 // ... sum up
      }


      // display the sum of the first column and release 'sum'
      char szText[256];
      sprintf(szText, "The sum of the first column is: %f", sum[0]);
      MessageBox(szText);

      delete[] sum;

     // how to sort, randomize and reorder
      data->sort(0);                      // sort rows regarding column 0, i.g. the first column
      data->save("sort.dat");             // save

      data->randomize(4*data->nDS());     // randomize all rows
      data->save("rand.dat");             // save

      data->reorder();                    // restore original order
      data->save("original.dat");         // save

      data->release();                    // release
   }
   catch(TErrText err)
   {
      MessageBox(err.szErrText, "error:", MB_OK | MB_ICONERROR);
   }
}

Download Example Project