CLsqFit:GetPtObs

The GetPtObs method returns the observed value for an existing sample point.

Syntax

nWt = CLsqFit:GetPtObs( nIndex )

nWt = CLsqFit:GetPtObs( nIndex, nChannel )

nWt1, nWt2, nWt3, nWt4 = CLsqFit:GetPtObs( nIndex )

where

nIndex is the index of the point in the sample, beginning at index 1.

nChannel is the optional channel to select for multi-channel data.

nY is the value of the point.

nY1, nY2, nY3, nY4 are the values of a point that has multi-channel (e.g., RGB) values. The number of values returned equals the number of channels.

The GetPtObs method uses the index of the target point. The index must either be known from the order that points were added to the sample, or determined by matching the target point's values using FindPt or a more complicated procedure involving GetResid or other method.

Two formats are provided with a different number of return values. If the point uses single-channel data (i.e., typical numeric data) or you specify the channel, then a single value is returned. If the point involves multi-channel data, up to 4 values will be returned. The number of values returned is determined by the SetNumChannels method. The status can be modified using SetPtObs.

Example

The following example illustrates how to change the y value of an existing point. In this case, the target point's index is found by matching its values:

L = CLsqFit:new()	-- create a CLsqFit object
L:SetNumCoefs( 2 )	-- set 2 coefficients to fit a line
L:AddPt( 3.5, 5.15 )	-- add a point for x = 3.5, y = 5.15, weight = 1
	-- add more points
L:Fit()	-- Fit the line
	-- do something with the fit results
n = L:FindPt( 3.5, 5.15 )	-- find the point (if we don't know it has index 1)
y = L:GetPtObs(n)	-- get the point's y value
L:SetPtObs( n, y + 0.05 )	-- add 0.05 to the point value
L:Fit()	-- get a new fit result using the new value