Kernel density estimation (2D, 3D)

Kernel density estimation is to fit the sample data by smoothing the peak function , The continuous density curve is used to describe the distribution of random variables , Strong robustness 、 Weak model dependency . Now it has been widely used in dynamic evolution analysis , Kernel density estimation usually has two dimensions 、 Three dimensional representation , Here's the picture ：

（ The above pictures are taken from chenminghua , Liuwenfei , Wang Shan , etc. . The spatial pattern and evolution trend of urban ecological efficiency in the Yangtze River economic belt [J]. Resource Science , 2020, 42(6): 1087-1098. Mayulin , Mayunpeng . A study on the regional differences and convergence of the efficiency of science and technology resources allocation in China [J]. The study of quantitative economy, technology and economy ,2021,38(08):83-103.）

I applied this method in my writing , Students who need to do empirical analysis can leave a message .