ZedGraph plotting large amount of data

Question

Hi.

            PointPairList list = new PointPairList();
            LineItem myCurve = myPane.AddCurve("My Curve", list, Color.Blue,
                                    SymbolType.None);
            for (int x = y; x < buffer.Length; x++)
            {
                list.Add(x, buffer[x]);
            }

I have a file its size is 40 mb. I am reading the bytes and writing the data into buffer so buffer.lenght gets a large number. Thus program throws out of memory exception because of long for loop. How can i draw all bytes without taking out of memory exception.?

Answer 1

You will need to pre-process the byte array generating a smaller data set that is 2x the maximum horizontal width or your chart.

To display a chart that is maxWidth pixels wide you will do something like this .

int window = (buffer.Length / maxWidth) + 1;

for (int x = 0; x < buffer.Length; x += window)
{
    double min = double.MaxValue;
    double max = double.MinValue;

    for (int j = 0; j < window; j++)
    {
        int index = x + j;

        if (index < buffer.Length)
        {
            double value = buffer[x+j];
            if (value < min)
            {
                min = value;
            }

            if (value > max)
            { 
                max = value;
            }
        }
    }

    list.Add(x, min);
    list.Add(x + (window - 1), max);
}

If you zoom in you need to recalculate the point list so that you do not end up with the saw tooth line.