Create an object of class point from a data frame.
从数据框创建对象的类点。
An object of class point represents the observed data of a spatial process. This includes the spatial location of sampling sites and the values observed at those sites. A point object is stored as a data frame. The data frame must contain one column for the X coordinate and one column for the Y coordinate of each point, as well as any number of columns representing data observed at the
点的类的对象代表了观测数据的空间过程。这包括采样点的空间位置和在这些网站中观察到的值。 Point对象存储为一个数据框。必须包含的数据框的X坐标的一列和一列的每一个点的Y坐标,以及任意数量的列代表观察到的数据
用法----------Usage----------
point(dframe, x='x', y='y')
参数----------Arguments----------
参数:dframe
a data frame containing the x and y coordinates for each point and the variables observed at each point
含有的x和y坐标的数据框的每个点,在每个点处观察到的变量
参数:x
the name of the column in dframe that contains the x coordinate
的名称列在dframe的包含x坐标
参数:y
the name of the column in dframe that contains the y coordinate
在dframe的列的名称包含的y坐标