3.7.5.5 CurveCurveobj
LabTalk Object Type:
 External Object
The curve object provides for the following math operations on a data plot:
 Smoothing
 Integration
 Derivation
It also provides for baseline operations and peak selection.
See the common properties and methods of external objects.
Properties:
Common Curve Object Properties
Property

Access

Description

curve.baselinePts

Read/write numeric

Number of points used in baseline creation.

curve.data$

Read/write string

Name of the Y column in the worksheet to perform the operations on. This property must be set before performing an operation.

curve.derivDeg

Read/write numeric

Degree of differentiation: 0, 1, or 2.

curve.i1

Read/write numeric

Starting row index number of the selected range.

curve.i2

Read/write numeric

Ending row index number of the selected range. When i1 > 0, i2 must be specified.

curve.plotName$

Read/write string

The name of the graph containing the data to be acted on by the curve object. This property does not require setting.

curve.show

Read/write numeric

Display the integration area: 0 = do not show, 1 = show.

curve.smoothPts

Read/write numeric

Total number of points to be smoothed including point (must be odd and >= 3).

curve.x0

Read only numeric

Value of X at i1.

curve.x1

Read only numeric

Value of X at i2.

curve.y0

Read only numeric

Value of Y at i1.

curve.y1

Read only numeric

Value of Y at i2.

curve.ymax

Read only numeric

Maximum value of the active dataset with respect to the baseline.

curve.ymax0

Read only numeric

Maximum value of the active dataset with respect to zero.

curve.ymax0i

Read only numeric

Row index number for ymax0.

curve.ymax0x

Read only numeric

Value of X corresponding to ymax0.

curve.ymaxi

Read only numeric

Row index number for ymax

curve.ymaxx

Read only numeric

Value of X corresponding to ymax.

curve.ymin

Read only numeric

Minimum value of the active dataset with respect to the baseline.

curve.ymini

Read only numeric

Row index number for ymin.

curve.yminx

Read only numeric

Value of X corresponding to ymin.

Curve Object Properties Specific to Math Operations
Property

Access

Description

curve.base$

Read/write string

Name of the worksheet column that is used as a baseline. For integration, you must set this property. Set it to an existing dataset (curve.base$ = wks_colName;) or specify the following: (curve.base$ = "";). When curve.base$ is set to "", then the curve.integrate() method integrates from y = 0.

curve.integrate.area

Read/write numeric

Integral.

curve.polyDeg

Read/write numeric

The degree of the underlying polynomial used for smoothing. Values can range from 1 to 9.

curve.res

Read only numeric

Tolerance for deviation in X axis values. This value is fixed at 5%.

curve.result$

Read/write string

Name of the (existing) dataset that stores the results. This property must be set before performing the math operation.

curve.smoothLeftPts

Read/write numeric

The number of points on the right of the data point being smoothed when using curve.sgsmooth(). This property combined with curve.smoothRightPts make up the smoothing window and can not exceed 100 points. The window can be asymmetric about a particular data point  i.e., the number of points to the left of the point of interest can be different from the number to the right.

curve.smoothRightPts

Read/write numeric

The number of points on the right of the data point being smoothed when using curve.sgsmooth(). This property combined with curve.smoothLeftPts make up the smoothing window and can not exceed 100 points. The window can be asymmetric about a particular data point  i.e., the number of points to the left of the point of interest can be different from the number to the right.

curve.x$

Read/write string

Name of the X column to use for the math operation.

Curve Object Properties Specific to Baseline Operations and Peak Selection
Property

Access

Description

curve.areas$

Read/write string

Worksheet column used for storing areas between base points.

curve.basex$

Read/write string

Worksheet column used for storing X coordinate for the base points.

curve.basey$

Read/write string

Worksheet column used for storing Y coordinate for the base points.

curve.centers$

Read/write string

Worksheet column used for storing the center points.

curve.halfWidths$

Read/write string

Worksheet column used for storing the halfwidths.

curve.heights$

Read/write string

Worksheet column used for storing the heights.

curve.integrate.area

Read only numeric

Area under a single peak.

curve.integrate.center

Read only numeric

Center point of a single peak.

curve.integrate.halfwidth

Read only numeric

Halfwidth for a single peak.

curve.integrate.height

Read only numeric

Height of a single peak.

curve.markerIndex$

Read only string

Worksheet column used for storing the selected baseline points.

curve.maxPeakRange
(You must also set curve.minPeakRange and curve.minHeight.

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 0.
Set this property to be the percentage of the total number of points in curve.data$ that the peak must not exceed in order to be recognized as a peak.

curve.minDer

Read/write numeric

Minimum value of the first derivative below which a point is accepted.

curve.minHeight
(You must also set curve.minPeakRange and curve.maxPeakRange.)

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 0.
Set this property to be the percentage of the total amplitude (difference between min and max values) of curve.data$ that a peak must have, to be considered a peak. This property enables you to exclude noise when determining peaks.

curve.minPeakRange
(You must also set curve.maxPeakRange and curve.minHeight.)

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 0.
Set this property to be the percentage of the total number of points in curve.data$ that the peak must have in order to be recognized as a peak.

curve.peakDirection$

Read/write string

Holds the name of the dataset that will have either a P (for positive) or an N (for negative) in the Peaks worksheet. The indexes of the peaks will be loaded in curve.peakIndex$.

curve.peakIndex$

Read/write string

Worksheet column used for storing the index for the peak points.

curve.pickPeaks.minHeight
(You must also set curve.pickPeaks.rectHeight and curve.pickPeaks.rectWidth.)

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 1.
Set this property to be the percentage of the total amplitude (difference between min and max values) of curve.data$ that a peak must have, to be considered a peak. This property enables you to exclude noise when determining peaks.

curve.pickPeaks.rectHeight
(You must also set curve.pickPeaks.minHeight and curve.pickPeaks.rectWidth.)

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 1. When curve.pickPeaks.simple = 1, the curve.pickPeaks() method uses a search rectangle for peak picking. Curve.pickPeaks.rectHeight determines the height of the search rectangle. Set this property to be the percentage of the difference between the maximum and minimum values in curve.data$.

curve.pickPeaks.rectWidth
(You must also set curve.pickPeaks.rectHeight and curve.pickPeaks.minHeight.)

Read/write numeric

The value of this property is used for peak picking only if curve.pickPeaks.simple = 1. When curve.pickPeaks.simple = 1, the curve.pickPeaks() method uses a search rectangle for peak picking. Curve.pickPeaks.rectWidth determines the width of the search rectangle.
Set this property to be the percentage of the total range of values in curve.data$.

curve.pickPeaks.simple

Read/write numeric

Set this property to 1 if curve.data$ does not have a definable baseline. If curve.data$ has a definable baseline (even if irregular), then set curve.pickPeaks.simple = 0.

Methods:
Curve Object Methods Specific to Math Operations
Method

Description

curve.adjave()

Smoothing using the adjacent averaging method. The result is stored in curve.result$.

curve.deriv()

Differentiate. The result is stored in curve.result$.

curve.FFTSmooth()

Smoothing using the Fourier transform method. The result is stored in curve.result$.

curve.integrate()

Integrate. The result is stored in curve.result$.

curve.SGDeriv()

Differentiate using the SavitzkyGolay method. The result is stored in curve.result$.

curve.SGSmooth()

Smoothing using the SavitzkyGolay method. The result is stored in curve.result$.

Curve Object Methods Specific to Baseline Operations and Peak Selection
Method

Description

curve.baseline()

Find all points that make a baseline.

curve.mrkIntegrate()

Get the first baseline points on either side of the peak.

curve.pickPeaks()

Get all the peak points. The search method depends on property settings. See curve.pickPeaks.simple, curve.maxPeakRange, curve.minHeight, curve.minPeakRange, curve.pickPeaks.minHeight, curve.pickPeaks.rectHeight, curve.pickPeaks.rectWidth.

Examples:
Differentiation Using SavitzkyGolay Method
This script performs a differentiation using the SavitzkyGolay method:
//Create a new book and import the data
newbook;
string fpath$ = "Samples\Signal Processing\fftfilter1.dat";
string fname$ = system.path.program$ + fpath$;
impasc;
wks.addcol();
col(c)[L]$=Results;
//Assign datasets
curve.data$=%H_B;
curve.result$=%H_C;
curve.i1 = 1;
curve.smoothpts = 5;
curve.derivdeg = 1;
//Perform differentiation,
//fill Result column of original worksheet
curve.sgderiv();
Peak Integration from a Baseline
This script performs an integration from a baseline:
//Open a new worksheet
newbook;
//Import sample file;
string fpath$ = "Samples\Spectroscopy\Peaks with Base.DAT";
string fname$ = system.path.program$ + fpath$;
impasc;
//Create a column for results
wks.addcol();
col(D)[L]$=Results;
curve.data$ = %H_B;
curve.base$ = %H_C;
curve.result$ = %H_D;
//Perform integration,
//fill results column of original worksheet
curve.integrate();
//Send the total area to the script window
type "Area = $(curve.integrate.area)";
Example 3
This script finds peaks in the active data plot and adds the peak XY values and row index numbers to the original worksheet:
curve.reset(); //initialize
%W = %[%C,'_']; //get name of wks for active data in layer
%W!page.xlcolname = 0; //turn off Spreadsheet Cell Notation firstly;
%W!wks.addcol(Pkindex); //add column to store index value
%W!wks.addcol(Pkx); //add column to store x value
%W!wks.col$(%W!wks.ncols).type = 4; //set as X column
%W!wks.addcol(Pky); //add column to store y value
curve.data$ = %C; //dataset to find peak values
curve.peakIndex$ = %W_PkIndex;
curve.pickPeaks.rectHeight = .05;
curve.pickPeaks.rectWidth = .05;
curve.pickPeaks.minHeight = .05;
curve.pickPeaks(1); //pick peaks without a definable baseline
get %W_PkIndex e end;
for (ii = 1; ii <= end; ii += 1)
{
%B = curve.data$; // %B is current active dataset
index = %W_pkindex[ii]; // get peak index
%W_Pkx[ii] = xvalue(index,%B); // Set corresponding x value
%W_Pky[ii] = %B[index]; // Set corresponding y value
}
Example 4
This example use curve.smoothLeftPts and curve.smoothRightPts to set the smoothing points.
//Create a new book and import the data
newbook;
string fpath$ = "Samples\Signal Processing\fftfilter1.dat";
string fname$ = system.path.program$ + fpath$;
impasc;
wks.addcol();
wks.addcol();
//smoothing points = 10
col(c)[c]$=10point;
curve.data$=%h_B;
curve.result$=%h_c;
curve.smoothleftpts=2;
curve.smoothrightpts=3;
curve.smoothpts=curve.smoothleftpts + curve.smoothrightpts + 1;
curve.polyDeg = 2;
curve.derivdeg = 1;
curve.sgderiv();
