在空间分析过程中，经常要以栅格单元为单位进行栅格统计分析，用到的统计数据有栅格所有单元的最大值、最小值、平均值、标准差等，该源码实现了此功能。-In the process of spatial analysis, often with grid unit grid statistical analysis for the unit, use the statistical data of a grid of all unit maximum, minimum, average, poor st