QT customplot not correct

Question

I am trying to plot graph from the CSV file of airfoil. I am able to store value in and array of QStringList and plot it. But, there is an abrupt jump at zero value. I have seen the output in qDebug it shows correct value. Please help. I can't figure out the problem.

Here is my code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFile>
#include <QTextStream>
#include <QString>
#include <QMessageBox>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

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

static void process_line(const QByteArray &)
{
}

static void process_line(const QString &)
{
}

void MainWindow::on_read_clicked()
{
    QStringList fileData[1000];
    QStringList list2;
    QString line,line1;
    QString filename="C:/Users/PRASHANT/Desktop/xf-e197-il-200000.csv";

    QFile file(filename);
    if(!file.exists())
    {
        qDebug() << "NO File"<<filename;
    }
    else
    {
        qDebug() << filename<<"Success";
    }

    ui->textBrowser->clear();

    int i = 0;
    if (file.open(QIODevice::ReadOnly | QIODevice::Text))
    {
        QTextStream stream(&file);
        QStringList list2;

        while (!stream.atEnd())
        {

            line = stream.readLine();
            d1 = line.indexOf("Alpha");

            list2 = line.split(',', QString::SkipEmptyParts);
            fileData[i]=list2;
            if(list2.contains("Alpha"))
            {
                start=i;
            }

            i++;
        }
    }

    file.close();


    // generate some data:
    QVector<double> x1(120), y1(120),y2(120),y3(120),y4(120); // initialize with entries 0..100

    for (int i=1; i<117; i++)
    {
      x1[i] = QString(fileData[start+i][0]).toDouble();
      y1[i] = QString(fileData[start+i][1]).toDouble();
      y2[i] = QString(fileData[start+i][2]).toDouble();
      y3[i] = QString(fileData[start+i][4]).toDouble();
      y4[i] = y1[i]/y2[i];
      qDebug() << x1[i] << y1[i];
    }

    // create graph and assign data to it:
    ui->Cl_apha->addGraph();
    ui->Cl_apha->graph(0)->setData(x1, y1);
    ui->CD_alpha->addGraph();
    ui->CD_alpha->graph(0)->setData(x1,y2);
    ui->CM_alpha->addGraph();
    ui->CM_alpha->graph(0)->setData(x1,y3);
    ui->CL_vs_CD->addGraph();
    ui->CL_vs_CD->graph(0)->setData(x1,y4);

    // give the axes some labels:
    ui->Cl_apha->xAxis->setLabel("\u03B1");
    ui->Cl_apha->yAxis->setLabel("CL");
    ui->CD_alpha->xAxis->setLabel("\u03B1");
    ui->CD_alpha->yAxis->setLabel("CD");
    ui->CM_alpha->xAxis->setLabel("\u03B1");
    ui->CM_alpha->yAxis->setLabel("CM");
    ui->CL_vs_CD->xAxis->setLabel("\u03B1");
    ui->CL_vs_CD->yAxis->setLabel("CL/CD");

    // set axes ranges, so we see all data:
    ui->Cl_apha->xAxis->setRange(-10, 15);
    ui->Cl_apha->yAxis->setRange(-1, 1.5);
    ui->CD_alpha->xAxis->setRange(-10, 15);
    ui->CD_alpha->yAxis->setRange(-0.05, 0.1);
    ui->CM_alpha->xAxis->setRange(-10, 15);
    ui->CM_alpha->yAxis->setRange(-0.2,0.05);
    ui->CL_vs_CD->xAxis->setRange(-10, 15);
    ui->CL_vs_CD->yAxis->setRange(-20, 85);
    ui->Cl_apha->replot();
    ui->CD_alpha->replot();
    ui->CM_alpha->replot();
    ui->CL_vs_CD->replot();
}

void MainWindow::on_write_clicked()
{
    QString fileName ="C:/Destination.txt";
    QFile file(fileName);
}

Here is the debug output:

"C:/Users/PRASHANT/Desktop/xf-e197-il-200000.csv"  Success...
-10.75 -0.3896
-10.5 -0.4297
-10.25 -0.4338
-10 -0.4179
-9.75 -0.4017
-9.5 -0.405
-9.25 -0.4173
-9 -0.4406
-8.75 -0.4813
-8.5 -0.5118
-8.25 -0.5597
-8 -0.5294
-7.75 -0.5
-7.5 -0.4699
-7.25 -0.4375
-7 -0.4083
-6.75 -0.3814
-6.5 -0.3562
-6.25 -0.3319
-6 -0.3116
-5.75 -0.2891
-5.5 -0.2676
-5.25 -0.2467
-5 -0.2264
-4.75 -0.2038
-4.5 -0.181
-4.25 -0.1584
-4 -0.1349
-3.75 -0.11
-3.5 -0.0844
-3.25 -0.0586
-3 -0.0324
-2.75 -0.0067
-2.5 0.0197
-2.25 0.0458
-2 0.0721
-1.75 0.0989
-1.5 0.1245
-1.25 0.1508
-1 0.1775
-0.75 0.2026
-0.5 0.2282
-0.25 0.2542
0 0.2784
0.25 0.3054
0.5 0.3389
0.75 0.3777
1 0.4205
1.25 0.4694
1.5 0.5191
1.75 0.5702
2 0.5972
2.25 0.6155
2.5 0.6374
2.75 0.6609
3 0.6816
3.25 0.7056
3.5 0.7295
3.75 0.7518
4 0.7775
4.25 0.7995
4.5 0.8246
4.75 0.8482
5 0.8729
5.25 0.897
5.5 0.9219
5.75 0.9453
6 0.9716
6.25 0.9936
6.5 1.0172
6.75 1.0415
7 1.0643
7.25 1.0859
7.5 1.1067
7.75 1.1263
8 1.1452
8.25 1.1618
8.5 1.1748
8.75 1.1804
9 1.1795
9.25 1.1739
9.5 1.1679
9.75 1.1641
10 1.1629
10.25 1.1618
10.5 1.1609
10.75 1.159
11 1.1573
11.25 1.1548
11.5 1.1486
11.75 1.1425
12 1.1415
12.25 1.141
12.5 1.1366
12.75 1.1421
13 1.1466
13.25 1.1508
13.5 1.1543
13.75 1.1634
14 1.1718
14.25 1.18
14.5 1.1884
14.75 1.1949
15 1.1989
15.25 1.2009
15.5 1.1996
15.75 1.1953
16 1.1873
16.25 1.1764
16.5 1.1598
16.75 1.1414
17 1.1209
17.25 1.0971
17.5 1.0722
17.75 1.0455
18 1.0162

output graph enter image description here

image of output http://i65.tinypic.com/fe3o1k.jpg – Prashant Kumar Jul 13 '17 at 08:29 — Prashant Kumar, Jul 13 '17 at 08:29

score 0 · Answer 1 · answered Jul 13 '17 at 10:19

0

It seems your code is fine, but for zero value is related to .toDouble() function in your file there are values that can't converted from string to double value.
Check this function by pass a boolean variable by refrence and a if cluse like code below to find missed data.

bool ok = false;
double temp = QString(fileData[start+i][0]).toDouble(&ok);
if (ok == false)
{
    qDebug() << QString(fileData[start+i][0]);
}

answered Jul 13 '17 at 10:19

saeed

2,477
2
23
40

try set data to qCustomPlot by data that you have generated, like a simple demo of qCustomPlot. I am sure that you have error on converting data to double. – saeed Jul 13 '17 at 11:18

QT customplot not correct

1 Answers1