Read data and add it to a chart

[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.

[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

[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
}

[deleted286]

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

[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...

[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?

[deleted286]

@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?

[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...

[deleted286]

@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

[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
}

[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.

[mrjj]

@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.