LineFromNPoints

Constructs a line from a list of points.

Inputs

Parameter

Description

Image

This argument must reference a spreadsheet cell that contains a valid Image data structure. By default, the cell referenced is cell A0, containing the AcquireImage function.

Point 0

Specifies the coordinates of the first point.

Point X 0	The X coordinate of the first point.
Point Y 0	The Y coordinate of the first point.

Point 1

Specifies the coordinates of the second point.

Point X 1	The X coordinate of the second point.
Point Y 1	The Y coordinate of the second point.

Point 2..N

Specifies the coordinates of any additional points.

Point X N	The X coordinate of the Nth point.
Point Y N	The Y coordinate of the Nth point.

Show

Specifies the graphics items to be displayed on a permanent basis.

0 = hide all	All graphics items are hidden except when the cell containing the LineFromNPoints function is the active cell in the spreadsheet.
1 = result graphics only	The fitted line graphic is displayed at all times. The input points are only displayed when the cell containing the LineFromNPoints function is the active cell in the spreadsheet.
2 = input and result graphics	The fitted line and the input points are displayed at all times.

Outputs

Returns

A LineFit data structure if two or more valid points are included in data, or #ERR if only one or no valid point is included in data.

Results

When the function is initially inserted into a cell, the following LineFit Vision Data Access functions are automatically inserted into the spreadsheet to create a result table:

Label	Function	Description
X0	GetX(LineFit, 0)	The X coordinate of the first endpoint.
Y0	GetY(LineFit, 0)	The Y coordinate of the first endpoint.
X1	GetX(LineFit, 1)	The X coordinate of the second endpoint.
Y1	GetY(LineFit, 1)	The Y coordinate of the second endpoint.
Chi2	GetChi2(LineFit)	The sum of the squares of the distances from the points to the line.

Additional data elements can be accessed using the following Vision Data Access functions:

Label	Function	Description
Distance	GetDistance(LineFit, Index)	The distance between the indexed point and the line.
MaxDist	GetMaxDist(LineFit)	The point that is farthest from the line.
MaxDistIndex	GetMaxDistIndex(LineFit)	The index of the point that is farthest from the line.
NPointsUsed	GetNPointsUsed(LineFit)	The number of points used to compute the line.