Detecting peak value on realtime data stream - c++

Question

I'm using QCustomPlot to read and display realtime value from an IMU. This is how I set the realtimeDataSlot:
void Settings::realtimeDataSlot(double x_acceleration_g, double y_acceleration_g, double z_acceleration_g, double z_acceleration_gnew)
{
static QTime time(QTime::currentTime());
// calculate two new data points:
double key = time.elapsed()/1000.0; // time elapsed since start of demo, in seconds
static double lastPointKey = 0;
if (key-lastPointKey > 0.02) // at most add point every 20 ms
{
// add data to lines:
ui->customPlot->graph(0)->addData(key, x_acceleration_g); // X axis
ui->customPlot->graph(1)->addData(key, y_acceleration_g); // Y axis
ui->customPlot->graph(2)->addData(key, z_acceleration_g); // Z axis
ui->customPlot->graph(3)->addData(key, z_acceleration_gnew);
lastPointKey = key;
}
// make key axis range scroll with the data (at a constant range size of 8):
ui->customPlot->xAxis->setRange(key, 8, Qt::AlignRight);
ui->customPlot->replot();
// calculate frames per second:
static double lastFpsKey;
static int frameCount;
++frameCount;
if (key-lastFpsKey >2) // average fps over 2 seconds
{
ui->statusbar->showMessage(
QString("%1 FPS, Total Data points: %2")
.arg(frameCount/(key-lastFpsKey), 0, 'f', 0)
.arg(ui->customPlot->graph(0)->data()->size()+ui->customPlot->graph(1)->data()->size())
, 0);
lastFpsKey = key;
frameCount = 0;
}
}
which shows me as follows:
As a next step, I need to detect the peaks in any axis, say for example in the above figure in the Y axis there are peak values which I need to detect and count. Can somebody show me a way to do this?
Thanks in advance
EDIT
I marked in the peaks following figure:
I define peak as the figure that value (positive values) more than 0.25 g at high rate.

Answer 1

How to do it for the y-axis:
you define a window size on the x-axis, say 5 x-values of 100
let that window move from start to end of the x-axis, which means: for the first measure, look at the x-values number 0,1,2,3,4 and for the second measure, look at the x-values number 1,2,3,4,5 and so on
for each window measure: determine the maximum y-value in that window, and increase a score counter for the appropriate x-value.
after the complete move of the window from start to end you need to find the x-values with the highest score counters.
The size of your window gives you the number of peaks.
Also do the same for the minimum values to find the negative peaks.
Take care at the start and end of the graph.