ocmath_find_peaks_2nd_derivative

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

Description

Find curve's peaks by 2nd derivative.

Syntax

int ocmath_find_peaks_2nd_derivative( UINT * lSize, const double * px, const double * py, double * pxPeaks, double * pyPeaks, int * pnIndices, DWORD dwCtrl, int nDerivativeMethod = 1, double * pSecondDeriv=NULL, int nPtsSmooth = 11, int nPolyOrder=2)

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.
dwCtrl: [input] combine of POSITIVE_DIRECTION, NEGATIVE_DIRECTION, KEEP_OPPOSITE_SIDE
nDerivativeMethod: [input] derivative method: DERIVATIVE_WITHOUT_SMOOTH = 0, DERIVATIVE_WITH_ADJ_SMOOTH, DERIVATIVE_USE_SG_SECOND_DERIV, DERIVATIVE_WITH_CONTINUOUS_SG_FIRST_DER_SMOOTH
pSecondDeriv: [output] to keep second derivative vector of different methods
nPtsSmooth: [input] smooth points number
nPolyOrder: [input] polynomial order of SG derivative method

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 feets of
//the peaks. The result is output in a new worksheet and the feets will plot in the 
//original data plot.
void ocmath_find_peaks_2nd_derivative_ex1( )
{
    GraphLayer gl = Project.ActiveLayer();
    if (!gl)
    {
        return;
    }
 
    //get data from the first data plot
    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_2nd_derivative( &nDataSize, vxData, vyData, vxPeaks, vyPeaks, vnIndices, POSITIVE_DIRECTION | NEGATIVE_DIRECTION, 1, NULL, 11, 3);
    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);
    
    //show the feets 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);
}