"""
Matplotlib based plotting utilities
"""
import math
import matplotlib.pyplot as plt


def plot_arrow(x, y, yaw, arrow_length=1.0,
 origin_point_plot_style="xr",
 head_width=0.1, fc="r", ec="k", **kwargs):
 """
 Plot an arrow or arrows based on 2D state (x, y, yaw)

 All optional settings of matplotlib.pyplot.arrow can be used.
 - matplotlib.pyplot.arrow:
 https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.arrow.html

 Parameters
 ----------
 x : a float or array_like
 a value or a list of arrow origin x position.
 y : a float or array_like
 a value or a list of arrow origin y position.
 yaw : a float or array_like
 a value or a list of arrow yaw angle (orientation).
 arrow_length : a float (optional)
 arrow length. default is 1.0
 origin_point_plot_style : str (optional)
 origin point plot style. If None, not plotting.
 head_width : a float (optional)
 arrow head width. default is 0.1
 fc : string (optional)
 face color
 ec : string (optional)
 edge color
 """
 if not isinstance(x, float):
 for (i_x, i_y, i_yaw) in zip(x, y, yaw):
 plot_arrow(i_x, i_y, i_yaw, head_width=head_width,
 fc=fc, ec=ec, **kwargs)
 else:
 plt.arrow(x, y,
 arrow_length * math.cos(yaw),
 arrow_length * math.sin(yaw),
 head_width=head_width,
 fc=fc, ec=ec,
 **kwargs)
 if origin_point_plot_style is not None:
 plt.plot(x, y, origin_point_plot_style)