Description Usage Arguments Details Value Note Author(s) References See Also Examples

This function fits a spherical principal curve.

1 2 3 |

`data` |
matrix or data frame consisting of spatial locations with two columns. Each row represents a longitude and latitude. |

`q` |
numeric value of the smoothing parameter. Intuitively speaking, the role of this argument is similar to the that of bandwidth for kernel regression. The value should be a numeric value between 0.01 and 0.5. The default is 0.1. |

`T` |
the number of points in the resulting curve. |

`step.size` |
step size of the |

`maxit` |
maximum number of iterations. |

`type` |
type of mean on the sphere. The default is "Intrinsic" and the other choice is "Extrinsic". |

`thres` |
threshold of the stopping condition. |

`deletePoints` |
logical value. The argument is an option of whether to delete points or not. If |

`plot.proj` |
logical value. If the argument is TRUE, the projection line for each data is plotted. The default is FALSE. |

`kernel` |
kind of kernel function. The default is quartic kernel and alternatives are indicator or Gaussian. |

`col` |
four-dimensional vector which represents colors of data, points in the resulting curves, the connecting line between points in the resulting curves, and projection lines, respectively. |

`size` |
three-dimensional vector which represents sizes of data, points in the principal curves, and the connecting line between points in the curves, respectively. |

This function fits a spherical principal curves, and requires to load the 'rgl', 'sphereplot', and 'geosphere' R packages.

plot and a list consisting of

`prin.curves` |
spatial points of in the resulting principal curves. |

`line` |
connecting line bewteen points of |

`converged` |
whether or not the algorithm converged. |

`iteration` |
the number of iterations of the algorithm. |

`recon.error` |
sum of squared distances from the data to their projections. |

`num.dist.pt` |
the number of distinct projections. |

This function requires to load 'rgl', 'sphereplot', and 'geosphere' R packages.

Jongmin Lee

Jang-Hyun Kim, Jongmin Lee, Hee-Seok Oh. (2020). Spherical Principal Curves <arXiv:2003.02578>.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | ```
library(rgl)
library(sphereplot)
library(geosphere)
#### example 1: earthquake data
data(Earthquake)
names(Earthquake)
earthquake <- cbind(Earthquake$longitude, Earthquake$latitude)
SPC(earthquake, q = 0.1)
#### example 2: waveform data
n <- 200
alpha <- 1/3 # amplitude
freq <- 4 # frequency
sigma <- 2
lon <- seq(-180, 180, length.out = n)
lat <- alpha * 180/pi * sin(lon * pi/180 * freq) + 10 + sigma * rnorm(length(lon))
wave <- cbind(lon, lat)
SPC(wave, q = 0.05)
``` |

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