R: Small Dataset Example of He

exHe {cobs} | R Documentation

## Small Dataset Example of He

### Description

The `exHe` data frame has 10 rows and 2 columns. It is an example for which `smooth.spline` cannot be used.

### Usage

    data(exHe)

### Format

This data frame contains the following columns:

x

  only values 0, 1, and 2.

y

  10 randomly generated values

### Details

Xuming He wrote about this JUST FOR FUN:
I was testing COBS using the following "data". For comparison, I tried smooth.spline in S+. I never got an answer back! No warning messages either. The point is that even the well-tested algorithm like `smooth.spline` could leave you puzzled.

To tell you the truth, the response values here were generated by white noise. An ideal fitted curve would be a flat line. See for yourself what COBS would do in this case.

### Source

Originally found at the bottom of `http://ux6.cso.uiuc.edu/~x-he/ftp.html`, the web resource directory of Xuming He at the time, say 2006.

### See Also

`cobs`

### Examples

    data(exHe)
    plot(exHe, main = "He's 10 point example and cobs() fits")
    tm <- tapply(exHe$y, exHe$x, mean)
    lines(unique(exHe$x), tm, lty = 2)

    cH. <- with(exHe,
        cobs(x, y, degree=1, constraint = "increase"))
    cH <- with(exHe,
        cobs(x, y, lambda=0.2, degree=1, constraint = "increase"))
    plot(exHe)
    lines(predict(cH.), type = "o", col="tomato3", pch = "i")# constant
    lines(predict(cH), type = "o", col=2, pch = "i")

    cHn <- cobs(exHe$x, exHe$y, degree=1, constraint = "none")
    lines(predict(cHn), col= 3, type = "o", pch = "n")

    cHd <- cobs(exHe$x, exHe$y, degree=1, constraint = "decrease")
    lines(predict(cHd), col= 4, type = "o", pch = "d")

[Package cobs version 1.3-3 Index]