How Can i Load data from file.ecg and plot it ?

[ahmed ali]

hello every body, i am a student in engineering, graduation stage.
i want to read data from file has an extension of .ecg or any extension and plot these data.
how can i do this ?
i am using qt 4.7.4 version
plz help me as i am really need this program.
thanks in advance

[ChrisW67]

You seem to be expecting some QReadAndInterpretECGorAnyFile class for an unspecified meaning of "ECG" or "any" file... it isn't going to happen.

The general proces implied by your general requirement is; open the file (QFile), read and interpret the file content (QFile, QIODevice, and/or QTextStream), and do something with the resulting data.

Qwt offers reasonable plotting facilities and also has a sub-forum here.

[ahmed ali]

thanks a lot for your help
but when i use this code i have some errors
i am using GUI application
can you help me to fix this?. sorry for annoying you but i am a beginner ... thanks in advance

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QFile>
#include<QtCore>
#include<QtGui>
#include<QTextStream>
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->label->setText("Hello User :)");
 
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_pushButton_clicked()
{
    QFile file("C:/ahmad/ecg test/tst.txt");
    if(!file.open( QFile::ReadOnly | QFile::Text))
    {
        ui->label->setText(" OOP : File Cant be Opened");
        return;
    }
    QStringList list;
    QTextStream in(&file);
    ui->label->setText("DONE : file opened");
    while (!in.atEnd())
    {
        list << in.readLine();
    }
   file.close();
data = new double[list.size()];
for(int i = 0; i< list.size(); i++)
    {
    data[i] = list[i].toDouble();
    }
dataSize = list.size();
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QFile>
#include<QtCore>
#include<QtGui>
#include<QTextStream>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->label->setText("Hello User :)");

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    QFile file("C:/ahmad/ecg test/tst.txt");
    if(!file.open( QFile::ReadOnly | QFile::Text))
    {
        ui->label->setText(" OOP : File Cant be Opened");
        return;
    }
    QStringList list;
    QTextStream in(&file);
    ui->label->setText("DONE : file opened");
    while (!in.atEnd())
    {
        list << in.readLine();
    }
   file.close();
data = new double[list.size()];
for(int i = 0; i< list.size(); i++)
    {
    data[i] = list[i].toDouble();
    }
dataSize = list.size();
}

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and the errors are:
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:38: error: C2248: 'QWidget::data' : cannot access private member declared in class 'QWidget'
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:38: error: C2440: '=' : cannot convert from 'double *' to 'QWidgetData *'
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:41: error: C2248: 'QWidget::data' : cannot access private member declared in class 'QWidget'
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:41: error: C2679: binary '=' : no operator found which takes a right-hand operand of type 'double' (or there is no acceptable conversion)
C:\QtSDK\Desktop\Qt\4.8.0\msvc2010\include\QtGui/qwidget.h(143): could be 'QWidgetData &QWidgetData::operator =(const QWidgetData &)'
while trying to match the argument list '(QWidgetData, double)'
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:43: error: C2065: 'dataSize' : undeclared identifier

[ChrisW67]

Where is the variable data declared? It appears that it is not declared, and coincidentally there is an existing member data of incompatible type inherited from QWidget, which is what the error message is telling you.

Rather than using a bare array (i.e. data) you should consider using QList or QVector which will manage the memory for you. You could also consider going straight from the line read from file to a QList<double> without the intervening QStringList.

[ahmed ali]

thanks a lot ChrisW67,
I tried to use this code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QFile>
#include<QtCore>
#include<QtGui>
#include<QList>
#include<QTextStream>
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->label->setText("Hello User :)");
 
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::on_pushButton_clicked()
{
    QFile file("C:/ahmad/ecg test/tst.txt");
    if(!file.open( QFile::ReadOnly | QFile::Text))
    {
        ui->label->setText(" OOP : File Cant be Opened");
        return;
    }
    QList<double> list;
    QTextStream in(&file);
    ui->label->setText("DONE : file opened");
    while (!in.atEnd())
    {
        list << in.readLine();
    }
   file.close();

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QFile>
#include<QtCore>
#include<QtGui>
#include<QList>
#include<QTextStream>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->label->setText("Hello User :)");

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    QFile file("C:/ahmad/ecg test/tst.txt");
    if(!file.open( QFile::ReadOnly | QFile::Text))
    {
        ui->label->setText(" OOP : File Cant be Opened");
        return;
    }
    QList<double> list;
    QTextStream in(&file);
    ui->label->setText("DONE : file opened");
    while (!in.atEnd())
    {
        list << in.readLine();
    }
   file.close();

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but unfortunately have some error too
C:\examples\Plot-build-desktop-Qt_4_8_0_for_Desktop_-_MSVC2010__Qt_SDK__Debug\..\..\Examples\Plot\mainw indow.cpp:36: error: C2678: binary '<<' : no operator found which takes a left-hand operand of type 'QList<T>' (or there is no acceptable conversion)

and if i have loaded the data to Qlist<double> list , how can i then plot these data ?

[ChrisW67]

You are trying to append a QString to a list of doubles. Perhaps you need to convert to double like you were before. Is there only one number on each line?

[ahmed ali]

yes, every line has one value
(i.e 1.8600000e+03
1.8640000e+03
1.8660000e+03
1.8550000e+03
1.8660000e+03
1.8760000e+03

[Spitfire]

Hmmm you need at least two coordinates to plot anything.
The values you have are probably Y values where time increases in constant.

try this:

MainWindow::MainWindow( QWidget* p )
    :
    QMainWindow( p ),
    plot( new QwtPlot( this ) ), // create plot widget
    x( QVector< double >() ),
    y( QVector< double >() )
{
    QToolBar* tb = this->addToolBar( "File" );
    tb->addAction( "Open File", this, SLOT( openFile() ) );
    this->setCentralWidget( this->plot );
}
 
void    MainWindow::openFile( void )
{
    QString str = QFileDialog::getOpenFileName( this );
    if( !str.isEmpty() )
    {
        QwtPlotCurve* curve = this->getCurve( str );
 
        if( !curve )
        {
            return;
        }
 
        curve->attach( this->plot );
        this->plot->replot();
    }
}
 
QwtPlotCurve*  MainWindow::getCurve( const QString& path )
{
    int size = 0;
 
    QFile src( path );
    if( !src.open( QIODevice::ReadOnly ) )
    {
        return NULL;
    }
 
    while( !src.atEnd() )
    {
        // x is placeholder if you don't have anything better
        this->x.append( size ); // this->y is QVector< double > which need to be kept alive as long as curve uses the data!
        this->y.append( src.readLine().toDouble() ); // this->x is QVector< double > which need to be kept alive as long as curve uses the data!
        ++size;
    }
 
    QwtPlotCurve* c = new QwtPlotCurve();
    c->setSamples( this->x.at( idx ).data(), this->y.at( idx ).data(), size );
    return c;
}

MainWindow::MainWindow( QWidget* p )
    :
    QMainWindow( p ),
    plot( new QwtPlot( this ) ), // create plot widget
    x( QVector< double >() ),
    y( QVector< double >() )
{
    QToolBar* tb = this->addToolBar( "File" );
    tb->addAction( "Open File", this, SLOT( openFile() ) );
    this->setCentralWidget( this->plot );
}

void    MainWindow::openFile( void )
{
    QString str = QFileDialog::getOpenFileName( this );
    if( !str.isEmpty() )
    {
        QwtPlotCurve* curve = this->getCurve( str );

        if( !curve )
        {
            return;
        }

        curve->attach( this->plot );
        this->plot->replot();
    }
}

QwtPlotCurve*  MainWindow::getCurve( const QString& path )
{
    int size = 0;

    QFile src( path );
    if( !src.open( QIODevice::ReadOnly ) )
    {
        return NULL;
    }

    while( !src.atEnd() )
    {
        // x is placeholder if you don't have anything better
        this->x.append( size ); // this->y is QVector< double > which need to be kept alive as long as curve uses the data!
        this->y.append( src.readLine().toDouble() ); // this->x is QVector< double > which need to be kept alive as long as curve uses the data!
        ++size;
    }

    QwtPlotCurve* c = new QwtPlotCurve();
    c->setSamples( this->x.at( idx ).data(), this->y.at( idx ).data(), size );
    return c;
}

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It's all you need to load a file and plot it.

[ahmed ali]

thanks a lot i will try it now and i will reply

[ahmed ali]

thanks a lot
i have tried it but having some errors

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QString>
 
#include <qwt_plot.h>
 
 
MainWindow::MainWindow( QWidget* p ):
    QMainWindow( p ),
    plot( new QwtPlot( this ) ), // create plot widget
    x( QVector< double >() ),
    y( QVector< double >() )
{
    QToolBar* tb = this->addToolBar( "File" );
    tb->addAction( "Open File", this, SLOT( openFile() ) );
    this->setCentralWidget( this->plot );
}
 
void MainWindow::openFile( void )
{
    QString str = QFileDialog::getOpenFileName( this );
    if( !str.isEmpty() )
    {
        QwtPlotCurve* curve = this->getCurve( str );
 
        if( !curve )
        {
            return;
        }
 
        curve->attach( this->plot );
        this->plot->replot();
    }
}
 
QwtPlotCurve*  MainWindow::getCurve( const QString& path )
{
    int size = 0;
 
    QFile src( path );
    if( !src.open( QIODevice::ReadOnly ) )
    {
        return NULL;
    }
 
    while( !src.atEnd() )
    {
        // x is placeholder if you don't have anything better
        this->x.append( size ); // this->y is QVector< double > which need to be kept alive as long as curve uses the data!
        this->y.append( src.readLine().toDouble() ); // this->x is QVector< double > which need to be kept alive as long as curve uses the data!
        ++size;
    }
 
    QwtPlotCurve* c = new QwtPlotCurve();
    c->setSamples( this->x.at( idx ).data(), this->y.at( idx ).data(), size );
    return c;
}
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QString>

#include <qwt_plot.h>


MainWindow::MainWindow( QWidget* p ):
    QMainWindow( p ),
    plot( new QwtPlot( this ) ), // create plot widget
    x( QVector< double >() ),
    y( QVector< double >() )
{
    QToolBar* tb = this->addToolBar( "File" );
    tb->addAction( "Open File", this, SLOT( openFile() ) );
    this->setCentralWidget( this->plot );
}

void MainWindow::openFile( void )
{
    QString str = QFileDialog::getOpenFileName( this );
    if( !str.isEmpty() )
    {
        QwtPlotCurve* curve = this->getCurve( str );

        if( !curve )
        {
            return;
        }

        curve->attach( this->plot );
        this->plot->replot();
    }
}

QwtPlotCurve*  MainWindow::getCurve( const QString& path )
{
    int size = 0;

    QFile src( path );
    if( !src.open( QIODevice::ReadOnly ) )
    {
        return NULL;
    }

    while( !src.atEnd() )
    {
        // x is placeholder if you don't have anything better
        this->x.append( size ); // this->y is QVector< double > which need to be kept alive as long as curve uses the data!
        this->y.append( src.readLine().toDouble() ); // this->x is QVector< double > which need to be kept alive as long as curve uses the data!
        ++size;
    }

    QwtPlotCurve* c = new QwtPlotCurve();
    c->setSamples( this->x.at( idx ).data(), this->y.at( idx ).data(), size );
    return c;
}
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

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1st problem is i QWT library not installed and i have read lot of threads but unfortunately i cant install it
2nd problem is i am a beginner and i feel there is some thing wrong in my above code
can i get help to fix these errors?
thanks in advance

[ChrisW67]

1st problem is i QWT library not installed and i have read lot of threads but unfortunately i cant install it

If this is the case then you cannot even compile the code above.

You do not need forum threads, blogs or Google searches to install Qwt. The instructions are in the INSTALL file that comes with the Qwt source (as Uwe is constantly explaining).

If you follow the instructions in the INSTALL file, not somewhere else, and strike a problem then post a description of exactly what you did, and what you got that seems broken or wrong. The Qwt sub-forum might be a better place for that.

2nd problem is i am a beginner and i feel there is some thing wrong in my above code

Possibly, maybe even probably, but wait until you can build it before you worry about this.

[ahmed ali]

Hello Everybody
I have a file with extension of ECG (Demo.ecg) that is contain a ECG signals, but i have a problem to load this file and plot it using Qwt
http://www.mediafire.com/?3ngo1nwxcbb6z9c
can any one help me?
thanks in advance

[ChrisW67]

Why start a new thread for the same problem? Please attach the file to your post rather than leave it on on a third-party site.

Now we know that the ECG file is not a text file this somewhat changes the solution you were attempting in the other thread. QTextStream is not the correct tool for the job: the input is not text. Do you know what the binary data layout is?

[ahmed ali]

thanks a lot
sorry for posting new thread about the same problem.

what do you mean by "binary data layout"?
if you mean the data of ecg file,
yes, the binary data layout is (for example)

-0.00300000000000000
-0.00200000000000000
-0.00100000000000000
0
0.00200000000000000
0.00400000000000000
0.00400000000000000
0.00600000000000000
0.00600000000000000
0.00700000000000000
0.00800000000000000
0.00900000000000000
0.0100000000000000
0.0100000000000000
0.00800000000000000
0.00600000000000000
0.00200000000000000
-0.00100000000000000
-0.00300000000000000
-0.00300000000000000
-0.00300000000000000
-0.00100000000000000
0.00100000000000000
0.00400000000000000
0.00500000000000000
0.00400000000000000
0.00200000000000000
-0.00200000000000000
-0.004000
My problem is how to load these data from the file of extension of ECG and plot it
can i convert this file format to txt format ? but using Qt?
thanks in advance

[MarekR22]

As far I could find *.ecg file is a binary file.
If you have some documentation what is the format of the file (binary layout) then I can help you how to read those data and how to plot them with Qwt6.

[ahmed ali]

As far I could find *.ecg file is a binary file.
If you have some documentation what is the format of the file (binary layout) then I can help you how to read those data and how to plot them with Qwt6.

thanks in advance for your help i will try to find some documentation what is the format of the file (binary layout)

master of zen <<< OK

[wysota]

My problem is how to load these data from the file of extension of ECG and plot it
can i convert this file format to txt format ?

You have to understand one thing. The extension of a file does not determine its contents. There may be several types of file using the same file extension. I have seen one file format for electrocardiography but that was indeed a textual format (as far as I read on their webpage) and what you provided is a binary file. Without reverse engineering the file it is not possible for us to determine the layout of the file and I'm sure nobody here is going to spend hours of their time analyzing your file. So please do your homework and find out (maybe from a person who gave you the file?) what the file really is and whether there are already existing libraries that can read this format and output numerical data such as those you have pasted in your post. Once you have those numbers, plotting them should be simple.