# Plot an arrow

### Description

It plots a polygon arrow subject to criteria concerning position, length, width, direction and color.

In plots of the cross-wavelet power (or wavelet coherency) spectrum of two time series as performed by function `wc.image`

,
arrows are used as a symbolic indicator of phase-differences between the series in the time/frequency domain.

This code has been developed by Huidong Tian (archived R package `WaveletCo`

).

### Usage

1 | ```
arrow(x, y, l = 0.1, w = 0.3*l, alpha, col.arrow = 'black')
``` |

### Arguments

`x` |
the x coordinate of the center of the arrow. |

`y` |
the y coordinate of the center of arrow. |

`l` |
the length of arrow. Default: 0.1. |

`w` |
the width of arrow. Default: 0.3*l. |

`alpha` |
the direction of the arrow, range from 0 to 2*pi. |

`col.arrow` |
color of arrows. Default: "black". |

### Author(s)

Code developed by Huidong Tian.

### References

Tian, H., and Cazelles, B., 2012. `WaveletCo`

. Available at http://cran.r-project.org/src/contrib/Archive/WaveletCo/, archived April 2013; accessed July 26, 2013.