ocmath_find_peaks_by_search_window

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 header to Include
9 Reference

Description

Find peaks in local scope.

Syntax

int ocmath_find_peaks_by_search_window( UINT * lSize, const double * pX, const double * pY, double * pXPeaks, double * pYPeaks, int * pnIndices, int nDir, double dSearchWidth, double dSearchHeight )

Parameters

lSize: [modify] on input, size of pX, pY, pXPeaks, pYPeaks, pnIndices; on output, return number of peaks
pX: [input] it contains curve's X coordinate's datas
pY: [input] it contains curve's Y coordinate's datas
pXPeaks: [output] Its size is equal to the size of px. it contains peaks' X coordinate's datas,; if the number of peaks is less than its size, the excrescent elements of it are filled; with 0.
pYPeaks: [output] Its size is equal to the size of py. it contains peaks' Y coordinate's datas,; if the number of peaks is less than its size, the excrescent elements of it are filled; with 0.
pnIndices: [output] Its size is equal to the size of px. it contains peaks' indices, if peaks's number is less than its size, the excrescent elements of it are filled with 0.
nDir: [input]; BOTH_DIRECTION: find peaks in both direction; NEGATIVE_DIRECTION: only find peaks in negative direction; POSITIVE_DIRECTION: only find peaks in positive direction
dSearchWidth: [input] window x axle size, defines local peak's x axle scope.
dSearchHeight: [input] window y axle size, defines local peak's y axle scope.

Return

Return OE_NOERROR if succeed, otherwise, non-zero error code is returned.

Examples

EX1

//Assume in the current graph, curve's XY data is in the first data plot. This piece
//of code get the XY data of the curve from the first data plot and find the peaks.
//The result is output in a new worksheet and the feets will plot in the original 
//data plot.
void ocmath_find_peaks_by_search_window_ex1( )
{
    GraphLayer gl = Project.ActiveLayer();
    if (!gl)
    {
        return;
    }
 
    //get datas from the first dataplot
    DataPlot dp = gl.DataPlots(0);        
    DataRange dr;
    vector vxData, vyData;
    if(dp.GetDataRange(dr))
    {
        DWORD dwPlotID;
        if(dr.GetData(DRR_GET_DEPENDENT | DRR_NO_FACTORS, 0, &dwPlotID, NULL, &vyData, &vxData) < 0)
        {
            printf("get_plot_data failed GetData");
            return;
        }
    }
 
    uint nDataSize = vxData.GetSize();
    int iSize = vxData.GetSize();
 
    vector vxPeaks, vyPeaks;
    vector<int> vnIndices;
 
    vxPeaks.SetSize(nDataSize);
    vyPeaks.SetSize(nDataSize);
    vnIndices.SetSize(nDataSize);
 
    int nRet = ocmath_find_peaks_by_search_window( &nDataSize, vxData, vyData, vxPeaks, vyPeaks, vnIndices, POSITIVE_DIRECTION | NEGATIVE_DIRECTION, 11, 20);
    if( nRet < OE_NOERROR )
    {
        printf("error code: %d\n", nRet);
        return;
    }
    vxPeaks.SetSize(nDataSize);
    vyPeaks.SetSize(nDataSize);
    vnIndices.SetSize(nDataSize);
    
    //new a worksheet to output the result
    WorksheetPage wksPage;
    wksPage.Create();
    Worksheet wksResult = wksPage.Layers(0);
    int nIndCol, nXCol, nYCol;
    nIndCol = wksResult.AddCol("Indices");
    nXCol = wksResult.AddCol("X Coordinate");
    nYCol = wksResult.AddCol("Y Coordinate");
    wksResult.Columns(nIndCol).SetType(OKDATAOBJ_DESIGNATION_X);
    wksResult.Columns(nXCol).SetType(OKDATAOBJ_DESIGNATION_X);
    wksResult.Columns(nYCol).SetType(OKDATAOBJ_DESIGNATION_Y);
    
    DataRange drOut;
    drOut.Add("X", wksResult, 0, nIndCol, -1, nIndCol);
    drOut.Add("Y", wksResult, 0, nXCol, -1, nXCol);
    drOut.Add("Z", wksResult, 0, nYCol, -1, nYCol);
    drOut.SetData(&vyPeaks, &vxPeaks, &vnIndices);
    
    //plot peaks in the data plot
    XYRange plotRange;
    plotRange.Add("X", wksResult, 0, nXCol, -1, nXCol);
    plotRange.Add("Y", wksResult, 0, nYCol, -1, nYCol);
    gl.AddPlot(plotRange, IDM_PLOT_SCATTER);
}

Remark

First, find local maximum point in a local scope selected by nSearchWidth. For a current point marked by nIndex, the scope is [nIndex-nLocalPts, nIndex+nLocalPts], where nLocalPts equals nSearchWidth/2+1.

If differences between y coordinates of the local maximum point and the two scope bound points are larger than nSearchHeight, the local maximum point will be save as a peak.