Improvement and optimization of Thiessen polygon method boundary treatment program

As an important method for the evaluation of quantity of area rainfall, Thiessen polygon method is widely applied because of its high calculation accuracy and fast computation. The calculation of Thiessen polygon method is simple because only area data of sample point is needed. When dataset is stable, accuracy of Thiessen polygon method is higher than the arithmetic average method. But there are still problems, for example boundary treatment and efficiency of Thiessen polygon method.