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Forum Update on Tuesday, May 27th 2025

Read data and add it to a chart

Scheduled Pinned Locked Moved Unsolved General and Desktop
chartreal time plotplottingtimerfile read
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  • jsulmJ jsulm

    @suslucoder said in Read data and add it to a chart:

    I should use another struct instead of string list, right?

    You should use what the method to set the data expects. That's why I suggested to read the documentation: it is documented quite clearly.

    D Offline
    D Offline
    deleted286
    wrote on last edited by
    #15

    @jsulm ıs there any example that doing exactly what you said?

    jsulmJ 1 Reply Last reply
    0
    • D deleted286

      @jsulm ıs there any example that doing exactly what you said?

      jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by jsulm
      #16

      @suslucoder I already posted a link to charts examples.
      For example: https://doc.qt.io/qt-5/qtcharts-temperaturerecords-example.html
      And you still did not tell us what data you actually want to show and what type of chart you need...

      https://forum.qt.io/topic/113070/qt-code-of-conduct

      1 Reply Last reply
      1
      • mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #17

        Hi
        Please show one line from the "C:/Users/ilknu/Documents/QFileDemo/abc.txt"
        so we know how data is. else it's impossible to give any hints on how you can show that in a chart.

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        • mrjjM mrjj

          Hi
          Please show one line from the "C:/Users/ilknu/Documents/QFileDemo/abc.txt"
          so we know how data is. else it's impossible to give any hints on how you can show that in a chart.

          D Offline
          D Offline
          deleted286
          wrote on last edited by
          #18

          @mrjj Here it is

          1991 01 213.5 136.9 0.64 220.5 147.6 229.4 205.5 8 17.4
          1991 02 270.2 167.5 0.62 221.5 147.6 243.0 206.3 10 18.4

          JonBJ 1 Reply Last reply
          0
          • D deleted286

            @mrjj Here it is

            1991 01 213.5 136.9 0.64 220.5 147.6 229.4 205.5 8 17.4
            1991 02 270.2 167.5 0.62 221.5 147.6 243.0 206.3 10 18.4

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by JonB
            #19

            @suslucoder

            QString line = read_one_line_from_file();
            QStringList list = line.split(QLatin1Char(' '), Qt::SkipEmptyParts);
            for (const QString &entry : list)
            {
                double num = entry.toDouble();    // or `unsigned num = entry.toUInt()` for the first 2 numbers on each line, by the look of it
                // do whatever is necessary with each `double` number retrieved
                // such as adding pairs directly to the chart, or building a `QLineSeries`, or whatever
            }
            
            D 1 Reply Last reply
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            • JonBJ JonB

              @suslucoder

              QString line = read_one_line_from_file();
              QStringList list = line.split(QLatin1Char(' '), Qt::SkipEmptyParts);
              for (const QString &entry : list)
              {
                  double num = entry.toDouble();    // or `unsigned num = entry.toUInt()` for the first 2 numbers on each line, by the look of it
                  // do whatever is necessary with each `double` number retrieved
                  // such as adding pairs directly to the chart, or building a `QLineSeries`, or whatever
              }
              
              D Offline
              D Offline
              deleted286
              wrote on last edited by
              #20

              @JonB Thank you. Where should I place the code script?

              jsulmJ 1 Reply Last reply
              0
              • D deleted286

                @JonB Thank you. Where should I place the code script?

                jsulmJ Offline
                jsulmJ Offline
                jsulm
                Lifetime Qt Champion
                wrote on last edited by
                #21

                @suslucoder said in Read data and add it to a chart:

                Where should I place the code script?

                Come on. Place is where you read the data from the file...

                https://forum.qt.io/topic/113070/qt-code-of-conduct

                D 1 Reply Last reply
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                • jsulmJ jsulm

                  @suslucoder said in Read data and add it to a chart:

                  Where should I place the code script?

                  Come on. Place is where you read the data from the file...

                  D Offline
                  D Offline
                  deleted286
                  wrote on last edited by
                  #22

                  @jsulm I know but i have, QString line = in.readLine();
                  allLines.append(line);
                  I couldnt get the idea about it. When i do it i get out of index error .And after doing all this things, how can i add my datas to a chart?

                  D jsulmJ 2 Replies Last reply
                  0
                  • D deleted286

                    @jsulm I know but i have, QString line = in.readLine();
                    allLines.append(line);
                    I couldnt get the idea about it. When i do it i get out of index error .And after doing all this things, how can i add my datas to a chart?

                    D Offline
                    D Offline
                    deleted286
                    wrote on last edited by
                    #23

                    @suslucoder I did this part. After that, how can i add it to a chart? Like the way create a new chart, append series and it goes like this?

                    1 Reply Last reply
                    0
                    • D deleted286

                      @jsulm I know but i have, QString line = in.readLine();
                      allLines.append(line);
                      I couldnt get the idea about it. When i do it i get out of index error .And after doing all this things, how can i add my datas to a chart?

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #24

                      @suslucoder said in Read data and add it to a chart:

                      And after doing all this things, how can i add my datas to a chart?

                      I already provided links to examples several times.

                      "When i do it i get out of index error" - then post your code...

                      https://forum.qt.io/topic/113070/qt-code-of-conduct

                      D 1 Reply Last reply
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                      • jsulmJ jsulm

                        @suslucoder said in Read data and add it to a chart:

                        And after doing all this things, how can i add my datas to a chart?

                        I already provided links to examples several times.

                        "When i do it i get out of index error" - then post your code...

                        D Offline
                        D Offline
                        deleted286
                        wrote on last edited by
                        #25

                        @jsulm ```
                        QString line = in.readLine();
                        allLines.append(line);
                        QStringList list = line.split(QLatin1Char(' '), Qt::SkipEmptyParts);
                        for(const QString &entry : list) {
                        double num = entry.toDouble();
                        }
                        series->append(num)
                        ``
                        Says use of undeclared identifier num

                        1 Reply Last reply
                        0
                        • mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by mrjj
                          #26

                          Hi
                          You want like

                          QStringList list = line.split(QLatin1Char(' '), Qt::SkipEmptyParts);
                          for(const QString &entry : list) {
                          double num = entry.toDouble();
                          series->append(X,Y);  // use num for either xor y or both depending on what you want
                          }
                          
                          SGaistS 1 Reply Last reply
                          1
                          • mrjjM mrjj

                            Hi
                            You want like

                            QStringList list = line.split(QLatin1Char(' '), Qt::SkipEmptyParts);
                            for(const QString &entry : list) {
                            double num = entry.toDouble();
                            series->append(X,Y);  // use num for either xor y or both depending on what you want
                            }
                            
                            SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #27

                            @mrjj said in Read data and add it to a chart:

                            series->append(num); // add each number from the line

                            This cannot work as QLineSeries does not have such an overload.

                            Currently discussed here.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            mrjjM 1 Reply Last reply
                            1
                            • SGaistS SGaist

                              @mrjj said in Read data and add it to a chart:

                              series->append(num); // add each number from the line

                              This cannot work as QLineSeries does not have such an overload.

                              Currently discussed here.

                              mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by mrjj
                              #28

                              @SGaist
                              Good catch.
                              yes its x,y.
                              It was more about num being undeclared at that point in time :)
                              Changed as not to confuse future readers.

                              1 Reply Last reply
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