说明：  根据多行三列的实验数据（x,y,signal)作出contourf图。其中x,y为二位空间位置（或其他概念的二维），signal为在该位置的信号。此代码先将数据按位置不同求平均，再将signal按照其对应的x,y分配到二位矩阵内。最后作图。编这个代码的初衷是为了制作大脑hippocampus区域place cell 活动性的contour 图。
(it s a code i made for plotting a contour graph of experimental data (x,y,signal). The data should be n*3 arrays which cannot be plot into contour directly. In fact, it can subplot 6*6 graphs or more, but speed might be slow..... especially, when you want more detailed graphs.)