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Read data and add it to a chart

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chartreal time plotplottingtimerfile read
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  • J jsulm
    4 Jan 2021, 08:26

    @suslucoder There are many examples: https://doc.qt.io/qt-5/qtcharts-examples.html
    Take time to see how data is added to a chart.

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    deleted286
    wrote on 4 Jan 2021, 08:30 last edited by
    #9

    @jsulm as you said, I already have the file content in allLines. When i do series.append(allLines) to adding chart I get an error. Thank you I will analyze the examples

    J J 2 Replies Last reply 4 Jan 2021, 08:36
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    • D deleted286
      4 Jan 2021, 08:30

      @jsulm as you said, I already have the file content in allLines. When i do series.append(allLines) to adding chart I get an error. Thank you I will analyze the examples

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      jsulm
      Lifetime Qt Champion
      wrote on 4 Jan 2021, 08:36 last edited by
      #10

      @suslucoder I told you in that other thread from you that you can't use a string list there. Please also read documentation...

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

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      • D deleted286
        4 Jan 2021, 08:30

        @jsulm as you said, I already have the file content in allLines. When i do series.append(allLines) to adding chart I get an error. Thank you I will analyze the examples

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        JonB
        wrote on 4 Jan 2021, 08:36 last edited by
        #11

        @suslucoder
        @jsulm already answered this last question in https://forum.qt.io/topic/122320/how-can-i-add-txt-file-datas-in-qlineseries/2. You cannot add a a string (or string list) to a chart, you have to parse it to generate the actual desired numbers.

        For adding data every few seconds: whether you read the lines from the file as you go or you read them all into a list in memory, either way on a QTimer::timeout() signal read the next however-many from the file/list and add them to the chart.

        D 1 Reply Last reply 4 Jan 2021, 08:45
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        • J JonB
          4 Jan 2021, 08:36

          @suslucoder
          @jsulm already answered this last question in https://forum.qt.io/topic/122320/how-can-i-add-txt-file-datas-in-qlineseries/2. You cannot add a a string (or string list) to a chart, you have to parse it to generate the actual desired numbers.

          For adding data every few seconds: whether you read the lines from the file as you go or you read them all into a list in memory, either way on a QTimer::timeout() signal read the next however-many from the file/list and add them to the chart.

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          deleted286
          wrote on 4 Jan 2021, 08:45 last edited by
          #12

          @JonB Okey. I understand. I should use another struct instead of string list, right?

          J J 2 Replies Last reply 4 Jan 2021, 08:49
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          • D deleted286
            4 Jan 2021, 08:45

            @JonB Okey. I understand. I should use another struct instead of string list, right?

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            J Offline
            JonB
            wrote on 4 Jan 2021, 08:49 last edited by
            #13

            @suslucoder
            Well it's not another "struct". You presumably have a file containing the text of numbers, perhaps separated by commas or new lines or something. You need to convert those to X,Y numeric values, and then pass those (or QPointFs) to add to the chart series. It doesn't matter whether you do that at the time of reading in the file or just before adding them to the series, but you will need to do so at one of those two stages.

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            • D deleted286
              4 Jan 2021, 08:45

              @JonB Okey. I understand. I should use another struct instead of string list, right?

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              J Offline
              jsulm
              Lifetime Qt Champion
              wrote on 4 Jan 2021, 08:52 last edited by
              #14

              @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.

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

              D 1 Reply Last reply 4 Jan 2021, 09:17
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              • J jsulm
                4 Jan 2021, 08:52

                @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.

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                deleted286
                wrote on 4 Jan 2021, 09:17 last edited by
                #15

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

                J 1 Reply Last reply 4 Jan 2021, 09:19
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                • D deleted286
                  4 Jan 2021, 09:17

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

                  J Offline
                  J Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on 4 Jan 2021, 09:19 last edited by jsulm 1 Apr 2021, 09:21
                  #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
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                    mrjj
                    Lifetime Qt Champion
                    wrote on 4 Jan 2021, 09:52 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.

                    D 1 Reply Last reply 4 Jan 2021, 10:39
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                    • M mrjj
                      4 Jan 2021, 09:52

                      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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                      deleted286
                      wrote on 4 Jan 2021, 10:39 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

                      J 1 Reply Last reply 4 Jan 2021, 10:49
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                      • D deleted286
                        4 Jan 2021, 10:39

                        @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

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                        J Offline
                        JonB
                        wrote on 4 Jan 2021, 10:49 last edited by JonB 1 Apr 2021, 10:53
                        #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 4 Jan 2021, 11:03
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                        • J JonB
                          4 Jan 2021, 10:49

                          @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
                          }
                          
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                          deleted286
                          wrote on 4 Jan 2021, 11:03 last edited by
                          #20

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

                          J 1 Reply Last reply 4 Jan 2021, 12:10
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                          • D deleted286
                            4 Jan 2021, 11:03

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

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                            J Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on 4 Jan 2021, 12:10 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 4 Jan 2021, 12:12
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                            • J jsulm
                              4 Jan 2021, 12:10

                              @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 4 Jan 2021, 12:12 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 J 2 Replies Last reply 4 Jan 2021, 12:26
                              0
                              • D deleted286
                                4 Jan 2021, 12:12

                                @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 4 Jan 2021, 12:26 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
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                                • D deleted286
                                  4 Jan 2021, 12:12

                                  @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?

                                  J Offline
                                  J Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on 4 Jan 2021, 12:27 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 4 Jan 2021, 12:58
                                  0
                                  • J jsulm
                                    4 Jan 2021, 12:27

                                    @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 4 Jan 2021, 12:58 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
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                                    • M Offline
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                                      mrjj
                                      Lifetime Qt Champion
                                      wrote on 4 Jan 2021, 13:03 last edited by mrjj 1 Apr 2021, 20:00
                                      #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
                                      }
                                      
                                      S 1 Reply Last reply 4 Jan 2021, 19:55
                                      1
                                      • M mrjj
                                        4 Jan 2021, 13:03

                                        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
                                        }
                                        
                                        S Offline
                                        S Offline
                                        SGaist
                                        Lifetime Qt Champion
                                        wrote on 4 Jan 2021, 19:55 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

                                        M 1 Reply Last reply 4 Jan 2021, 19:59
                                        1
                                        • S SGaist
                                          4 Jan 2021, 19:55

                                          @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.

                                          M Offline
                                          M Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on 4 Jan 2021, 19:59 last edited by mrjj 1 Apr 2021, 20:00
                                          #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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