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  4. how i can identify and read the columns of a csv file ?
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how i can identify and read the columns of a csv file ?

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  • mrjjM mrjj

    @julie546
    ok. and you used the same CSV file there ?

    and you compared the values we insert, value by value to make sure it reads as it should ?

    I mean if it could not convert for some reason it would silently continue.

     if(!ok)
       continue;
    

    some of the points to the far right seems more out there than on correct diagram.
    should be around 6.0 but is 6.8

    J Offline
    J Offline
    julie546
    wrote on last edited by
    #32

    @mrjj yes it's from the same csv file
    i have on the csv file 1500 value

    JonBJ 1 Reply Last reply
    0
    • J julie546

      @mrjj yes it's from the same csv file
      i have on the csv file 1500 value

      JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by
      #33

      @julie546
      As @mrjj said, just to humour us, in the two places you have

              if(!ok)
                  continue;
      

      please put in above the if

      Q_ASSERT(ok);
      

      (You'll need to have included #include <QtGlobal>, but probably something else you are including will have done this.)

      KroMignonK 1 Reply Last reply
      1
      • JonBJ JonB

        @julie546
        As @mrjj said, just to humour us, in the two places you have

                if(!ok)
                    continue;
        

        please put in above the if

        Q_ASSERT(ok);
        

        (You'll need to have included #include <QtGlobal>, but probably something else you are including will have done this.)

        KroMignonK Offline
        KroMignonK Offline
        KroMignon
        wrote on last edited by
        #34

        @JonB said in how i can identify and read the columns of a csv file ?:

        As @mrjj said, just to humour us, in the two places you have
        if(!ok)
        continue;

        please put in above the if
        Q_ASSERT(ok);

        The reason why there is continue, is because the CSV file contains the column headers, which are strings and cannot be converted to float.
        With Q_ASSERT() the program will be interrupted.

        It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

        mrjjM JonBJ 2 Replies Last reply
        1
        • KroMignonK KroMignon

          @JonB said in how i can identify and read the columns of a csv file ?:

          As @mrjj said, just to humour us, in the two places you have
          if(!ok)
          continue;

          please put in above the if
          Q_ASSERT(ok);

          The reason why there is continue, is because the CSV file contains the column headers, which are strings and cannot be converted to float.
          With Q_ASSERT() the program will be interrupted.

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #35

          @KroMignon
          ah so it should skip first col. always. good catch.
          Im just wondering if all points really get converted as
          else i dont see how the graphs can be that differnt.

          1 Reply Last reply
          0
          • KroMignonK KroMignon

            @JonB said in how i can identify and read the columns of a csv file ?:

            As @mrjj said, just to humour us, in the two places you have
            if(!ok)
            continue;

            please put in above the if
            Q_ASSERT(ok);

            The reason why there is continue, is because the CSV file contains the column headers, which are strings and cannot be converted to float.
            With Q_ASSERT() the program will be interrupted.

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by
            #36

            @KroMignon said in how i can identify and read the columns of a csv file ?:

            The reason why there is continue, is because the CSV file contains the column header

            Surely that's for the first line only?

            J 1 Reply Last reply
            0
            • JonBJ JonB

              @KroMignon said in how i can identify and read the columns of a csv file ?:

              The reason why there is continue, is because the CSV file contains the column header

              Surely that's for the first line only?

              J Offline
              J Offline
              julie546
              wrote on last edited by
              #37

              @JonB @mrjj @KroMignon
              I remove the headers and I replace
              if (! ok)
              continue;
              by Q_ASSERT (ok);
              but it's the same result

              KroMignonK 1 Reply Last reply
              0
              • J julie546

                @JonB @mrjj @KroMignon
                I remove the headers and I replace
                if (! ok)
                continue;
                by Q_ASSERT (ok);
                but it's the same result

                KroMignonK Offline
                KroMignonK Offline
                KroMignon
                wrote on last edited by
                #38

                @julie546 said in how i can identify and read the columns of a csv file ?:

                I remove the headers and I replace
                if (! ok)
                continue;
                by Q_ASSERT (ok);
                but it's the same result

                I suppose it is a simple precision issue, you should replace toFloat() with toDouble():

                while (!filelidar.atEnd()) {
                    QString line = filelidar.readLine();
                    const auto parts = line.split (',');
                    if(parts.size() >= 2)
                    {
                        bool ok;
                        qreal x = parts.at(0).toDouble(&ok);
                        if(!ok)
                        {
                            qDebug() << "Could not parse X value" << parts.at(0);
                            continue;
                        }
                        qreal y = parts.at(1).toDouble(&ok);
                        if(!ok)
                        {
                            qDebug() << "Could not parse Y value" << parts.at(1);
                            continue;
                        }
                        series->append(x, y);
                    }
                }
                

                It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                J 1 Reply Last reply
                0
                • KroMignonK KroMignon

                  @julie546 said in how i can identify and read the columns of a csv file ?:

                  I remove the headers and I replace
                  if (! ok)
                  continue;
                  by Q_ASSERT (ok);
                  but it's the same result

                  I suppose it is a simple precision issue, you should replace toFloat() with toDouble():

                  while (!filelidar.atEnd()) {
                      QString line = filelidar.readLine();
                      const auto parts = line.split (',');
                      if(parts.size() >= 2)
                      {
                          bool ok;
                          qreal x = parts.at(0).toDouble(&ok);
                          if(!ok)
                          {
                              qDebug() << "Could not parse X value" << parts.at(0);
                              continue;
                          }
                          qreal y = parts.at(1).toDouble(&ok);
                          if(!ok)
                          {
                              qDebug() << "Could not parse Y value" << parts.at(1);
                              continue;
                          }
                          series->append(x, y);
                      }
                  }
                  
                  J Offline
                  J Offline
                  julie546
                  wrote on last edited by
                  #39

                  @KroMignon thank you for your answer you helped me a lot,I tried it but it's the same thing, you don't think it's about this instruction ?
                  QScatterSeries * series = new QScatterSeries;
                  series->setMarkerShape(QScatterSeries::MarkerShapeRectangle);

                  KroMignonK JonBJ 2 Replies Last reply
                  0
                  • J julie546

                    @mrjj
                    thank you for your reply I have changed it but there are some missing points3.PNG
                    QScatterSeries * series = new QScatterSeries;
                    series->setMarkerShape(QScatterSeries::MarkerShapeRectangle);

                    S Offline
                    S Offline
                    SimonSchroeder
                    wrote on last edited by
                    #40

                    @julie546 said in how i can identify and read the columns of a csv file ?:

                    thank you for your reply I have changed it but there are some missing points

                    I am not sure that these points are actually missing. As far as I can tell you draw the points as blue squares with a white border (on a white background). If you look closely a lot of points are almost vanishing in the drawing (and some will vanish altogether). This is because the points are to close together (and some unfortunate pattern in your data) that the points overlap excactly so that you only see the white border of neighboring points (actually you don't see them as they are white on white). This makes it seem as if the points are missing.

                    Try changing either the background color or the color of the borders of the data points. Or remove the border to be comparable to Excel (if that is what you want). I can't help you with the right functions as I have never used these charts.

                    1 Reply Last reply
                    0
                    • J julie546

                      @KroMignon thank you for your answer you helped me a lot,I tried it but it's the same thing, you don't think it's about this instruction ?
                      QScatterSeries * series = new QScatterSeries;
                      series->setMarkerShape(QScatterSeries::MarkerShapeRectangle);

                      KroMignonK Offline
                      KroMignonK Offline
                      KroMignon
                      wrote on last edited by
                      #41

                      @julie546 said in how i can identify and read the columns of a csv file ?:

                      series->setMarkerShape(QScatterSeries::MarkerShapeRectangle);

                      This will only change the way the point is draw (https://doc.qt.io/qt-5/qscatterseries.html#markerShape-prop).
                      I don't think this will change anything.

                      Are you sure you have exported all points in your CSV file?
                      For me, it looks like positions are missed.

                      It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                      1 Reply Last reply
                      0
                      • J julie546

                        @KroMignon thank you for your answer you helped me a lot,I tried it but it's the same thing, you don't think it's about this instruction ?
                        QScatterSeries * series = new QScatterSeries;
                        series->setMarkerShape(QScatterSeries::MarkerShapeRectangle);

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by JonB
                        #42

                        @julie546
                        Your example currently has "many" points. Like anything you are trying to develop/debug, can't you cut down to something with as few points as possible while you get going? Can you go back to your original master and have like, dunno, half a dozen points (or start from 2?!), and compare how that is supposed to look against what you're getting in Qt Charts? That would eliminate all this discussion about whether you have the same number of points and whether it's just a coloring/display issue, or whatever.

                        1 Reply Last reply
                        1
                        • J Offline
                          J Offline
                          julie546
                          wrote on last edited by
                          #43

                          it is not a problem of color nor of value because I have checked the numbers of values ​​and it is the same with the csv file and I have changed the color but it is the same graph

                          JonBJ 1 Reply Last reply
                          0
                          • J julie546

                            it is not a problem of color nor of value because I have checked the numbers of values ​​and it is the same with the csv file and I have changed the color but it is the same graph

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by JonB
                            #44

                            @julie546
                            I still think it would help you and those trying to answer if you can reproduce a problem/difference with the absolute minimum of points to consider. Up to you.....

                            J 1 Reply Last reply
                            0
                            • JonBJ JonB

                              @julie546
                              I still think it would help you and those trying to answer if you can reproduce a problem/difference with the absolute minimum of points to consider. Up to you.....

                              J Offline
                              J Offline
                              julie546
                              wrote on last edited by
                              #45

                              @JonB how i can change please the color of the window to black ?

                              Pl45m4P 1 Reply Last reply
                              0
                              • J Offline
                                J Offline
                                julie546
                                wrote on last edited by
                                #46

                                I tested this code but it did not change the color
                                QMainWindow window;
                                window.setCentralWidget(chartView);
                                window.resize(1000, 900);
                                window.setStyleSheet("QMainWindow {background: 'black';}");

                                                       window.show(); 
                                

                                can you help me please

                                JonBJ 1 Reply Last reply
                                0
                                • J julie546

                                  @JonB how i can change please the color of the window to black ?

                                  Pl45m4P Offline
                                  Pl45m4P Offline
                                  Pl45m4
                                  wrote on last edited by
                                  #47

                                  @julie546 said in how i can identify and read the columns of a csv file ?:

                                  how i can change please the color of the window to black ?

                                  https://doc.qt.io/qt-5/qtcharts-customchart-example.html

                                  If you want the QChartbackground to be black, try

                                  chart->setBackgroundBrush(QBrush(Qt::Black));
                                  

                                  For QMainWindow:

                                  window.setStyleSheet("QMainWindow { background-color: black }");
                                  
                                  

                                  If debugging is the process of removing software bugs, then programming must be the process of putting them in.

                                  ~E. W. Dijkstra

                                  1 Reply Last reply
                                  2
                                  • J julie546

                                    I tested this code but it did not change the color
                                    QMainWindow window;
                                    window.setCentralWidget(chartView);
                                    window.resize(1000, 900);
                                    window.setStyleSheet("QMainWindow {background: 'black';}");

                                                           window.show(); 
                                    

                                    can you help me please

                                    JonBJ Offline
                                    JonBJ Offline
                                    JonB
                                    wrote on last edited by
                                    #48

                                    @julie546
                                    Try removing the quotes, window.setStyleSheet("QMainWindow {background: black;}");, and also you may need instead window.setStyleSheet("QMainWindow {background-color: black;}");?

                                    1 Reply Last reply
                                    1
                                    • J Offline
                                      J Offline
                                      julie546
                                      wrote on last edited by
                                      #49

                                      I solved the problem thank you for helping me it was because of the color
                                      @JonB @J-Hilk @KroMignon @Pl45m4 @SimonSchroeder

                                      1 Reply Last reply
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