11.9 The Interpolate Gadget


Video Image.png See more related video:Origin VT-0010 Interpolation

Overview

The Interpolate Gadget performs quick interpolation on a ROI (Region of Interest) range.

Interpolate Gadget.png

With this gadget, you can:

  • Easily interpolate data points on a rectangular region with the linear, cubic spline or cubic B-spline method.
  • Quickly find out an interpolated Y value from any given X value.
  • Output the interpolated values to Script Window, Result Log or a specified worksheet.
To Use Interpolate Gadget

To use this tool, select Gadgets: Interpolate from the Origin menu, when a graph is active.

Dialog Settings

This dialog can be opened from Gadgets: Interpolate in the Origin menu, or by selecting Preferences from the ROI fly-out menu.

ROI Box X Scale
Specify the X data range for the ROI.
From
The beginning X scale value.
To
The ending X scale value.
Fixed (Prevent moving by ROI)
Fix the X scale to prevent rescaling when moving the ROI box.

Show Tool Name

Specify whether to show the tool's name near the top of the ROI.

Fill Color

Specify the ROI fill color.

Interpolation Line Color

Specify the color of the interpolation line.

Interpolation Line Width

Specify the width of the interpolation line.
Show on Center-Top of ROI Box Choose the quantities to be displayed at the top of the ROI box.
Y at Left
The Y value that corresponds to the left edge of the ROI.
Y at Right
The Y value that corresponds to the right edge of the ROI.
Y at Specified X
The Y value that corresponds to an X value which you specify in the X edit box.
X
This edit box is available only when the Y at Specified X check box is checked.
Interpolate/Extrapolate Options Method
Specifies the interpolation/extrapolation method. Options include:
  • Linear
    Linear interpolation is a fast method of estimating a data point by constructing a line between two neighboring data points.
  • Cubic Spline
    This method splits the input data into a given number of pieces, and fits each segment with a cubic polynomial. The second derivative of each cubic function is set equal to zero. With these boundary conditions met, an entire function can be constructed in a piece-wise manner.
  • Cubic B-Spline
    This method also splits the input data into pieces. Each segment is fitted with discrete Bezier splines.
  • Akima Spline
    This method is based on a piecewise function composed of a set of polynomials. The akima interpolation is stable to outliers.
Please see the algorithm here.

Number of Points

Specify the number of interpolation/extrapolation points.

Boundary

Boundary condition is available when Method is Cubic Spline. Options include:
  • Natural
    The 2nd derivatives are 0 on both ends.
  • Not-A-Knot
    The 3rd derivatives are continuous on the second and last-second point.

Smoothing Factor

Available when Method is Cubic B-Spline. A non-negative parameter that specifies the smoothness of the interpolated curve in Cubic B-Spline interpolation. The factor helps user control the balance between smoothing and fidelity to the actual data. Larger values will result in smoother curves.

Fit Limits To

Specify the interpolation curve boundary.
  • Interpolate to Rectangle Edge
    Interpolate to the ROI edges. If the ROI range is larger than the source data range, the interpolation will stop at the edge of the source data.
  • Interpolate/Extrapolate to Rectangle Edge
    Interpolate/Extrapolate to the ROI edges, regardless of the source data range.
  • Data Points
    Interpolate between the specified data points, which are enclosed by the ROI rectangle.
  • Interpolate/Extrapolate to Full Axis Edge
    Interpolate/Extrapolate to the full X axis scale range in the input graph, regardless of the source data range.
  • Custom
    Interpolate/Extrapolate to a customized data range, specified by the Left and Right value.
Output To Specify the output result worksheet:
  • When you generate new output, results are output to [%H-Interpolate]Result by default (here %H means the Short Name of source graph), but other books and sheets can be specified. If the book and sheet do not exist, they will be created on output.
  • Alternately, you can click the flyout button Gadget flyout button.png to the right of Result Worksheet Name and choose Sheet in Input Book. This fills the edit box with [<input>]Result. When you generate new output, results are output to a sheet named Result in the source book.

Fly-out Menu

Click the triangle button ROI menu.png at the top right corner of the ROI tool to open the fly-out menu. Menu commands include:

New Output Output results to the specified worksheet.
New Output for All Curves (N) Output the results for all curves in the current layer to the specified worksheet (if not empty, append the results).
New Output for All Layers (L) Output the results for all curves in all layers within the current graph to the specified worksheet (if not empty, append the results).
Go to Report Worksheet Activate the report worksheet.
Change Data Select the source data set. This is applicable only when there are multiple curves on the graph.
  • By default, Auto mode is enabled. When Auto is enabled, plot selection is controlled by clicking on a plot in the graph window or Object Manager. Prior to Origin 2019, Origin did not support Auto; to change target plot/data in older versions, you must select a plot from the fly-out menu.
  • Place a check mark in front of any plot to select that plot.
  • Click Select... or More ... to open the Select Plot(s) dialog and change selection.
Expand to Full Plot(s) Range Expand the ROI to the full plot(s) range.
Fix ROI Position Fix the position of the ROI.
Interpolate X/Y Open the Interpolate Y from X dialog. You can enter multiple X values and the tool will output the interpolated Y values for each of them.
Save Theme Save the settings as a Theme.
Save as <default> Save the settings as default Theme.
Load Theme Load settings from a Theme file.
Preferences Open the Interpolate Preferences dialog.
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