TkSpline: Plot a set of data in a Tk window and interactively move a line to see predicted y-values from a spline fit corresponding to selected x-values.

Description

This function plots a dataset in a Tk window then draws the spline fit through the points. It places a line to show the predicted y from the given x value. The line can be clicked on and dragged to new x-values with the predicted y-values automatically updating. A table at the bottem of the graph shows the values and the 3 derivatives.

Usage

TkSpline(x, y, method='natural', snap.to.x=FALSE, digits=4,
                     col=c('blue','#009900','red','black'),
                     xlab=deparse(substitute(x)), ylab=deparse(substitute(y)),
                     hscale=1.5, vscale=1.5, wait=TRUE,
                     ...)

Arguments

The x-values of the data, should be sorted

The corresponding y-values of the data

method

Spline Method, passed to splinefun

snap.to.x

Logical, if TRUE then the line will only take on the values of x

digits

Number of digits to print, passed to format

col

Colors of the prediction and other lines

xlab

Label for the x-axis, passed to plot

ylab

Label for the y-axis, passed to plot

hscale

Horizontal scaling, passed to tkrplot

vscale

Vertical scaling, passed to tkrplot

wait

Should R wait for the window to close

...

Additional parameters passed to plot

Value

If wait is FALSE then an invisible NULL is returned, if wait is TRUE then an invisible list with the x and y values and derivatives is returned.

Details

This provides an interactive way to explore predictions from a set of x and y values. Internally the function splinefun is used to make the predictions. The x-value of the reference line can be changed by clicking and dragging the line to a new position. The x and y values are shown in the margins of the graph. Below the graph is a table with the y-value and derivatives.

Examples

Run this code

if(interactive()) {
  x <- 1:10
  y <- sin(x)
  TkSpline(x,y, xlim=c(0,11))
}