Delete datas from chart series, after adding them on a chart

[deleted286]

In the code script, i got datas from queue and add them into chart via series. Let say we have 10 data. When im adding the 6.data, i want to delete the first one. So, for showing new items on a chart, i should delete the old ones. How can i do such thing?

static float q_x;
  if(!queue.isEmpty())
   {
      double num=queue.dequeue();
      q_x += 0.1;
      series->append(q_x, num);
      chart->update();
      qDebug() << q_x << num;
    }

[jsulm]

@suslucoder There are several remove(...) methods in https://doc.qt.io/qt-5/qxyseries.html
Did you check that?

[deleted286]

@jsulm yes, i've checked them. I tried chart->series().removeFirst();

But i cant decide where should it placed?
It shoud remove after updating the chart with a new data, but when i placed it after chart->update, there are no lines in chart. I couldnt understand

[JonB]

@suslucoder
Since your code only appends one point at a time, if you remove one point in the same place it will go empty.

If you want to do something about

When im adding the 6.data, i want to delete the first one.

you need to write code to do that.

[deleted286]

@JonB Hmmmm, i got. actually what i want to do is scrolling my chart. I have about 20 point, and i cant see all of them on the secreen. It shows just up to the size of the axis, and the others cant seen on the secreen.
There are too many datas on the right but we cannot see.