v21i04.R

说明：  从plots文件中读取目标站点信息 从station文件读取气象站点信息 自动匹配距离目标站点最近的气象站名称(Automatically match the closest meteorogical station of subject plot.)

代码详细解释了bagging方法的运用，以及包含了详细的bagging代码(The code explains the application of bagging method in detail, and contains detailed bagging code.)

说明：  成都市空气中的O3来源及分析，可用于大创项目(O3 source and analysis in air of Chengdu, which can be used in some projects)

利用R语言SEM程序包进行通径分析，简单易学，容易上手(SEM path analysis model)

中国地面气候资料日值数据集(V3.0)处理程序，可以用来处理中国气象数据网上的气象数据(China surface climate data daily data set (V3.0) processing program can be used to process meteorological data on China Meteorological data online.)

利用R语言进行两个变量的空间自相关分析，从而进行克里金插值(The spatial autocorrelation analysis of two variables is carried out by using R language.)

较基础的R语言学习书籍，初学时比较适用。(R language programming)

说明：  本书提供了快速绘制高质量图形的150多种技巧，每个技巧用来解决一个特定的绘图需求。读者可以通过目录快速定位到自己遇到的问题，查询相应的解决方案。(This book provides more than 150 techniques for quickly drawing high quality graphics, each of which addresses a specific drawing requirement. Readers can quickly locate their own problems through the directory, query the corresponding solution.)

ADS-B接收，采用PlutoSDR板卡，基于matlab开发(ADS-B receives, uses PlutoSDR card, develops based on MATLAB)

双重差分估计 双重差分模型（difference-in-difference，DID）近年来多用于计量经济学中对于公共政策或项目实施效果 的定量评估。 通常大范围的公共政策有别于普通科研性研究，难以保证对于政策实施组和对照组在样本分配上的完全随机。非随机分配政策实施组和对照组的试验称为自然试验（naturaltrial），此类试验存在较显著的特点，即不同组间样本在政策实施前可能存在事前差异，仅通过单一前后对比或横向对比的分析方法会忽略这种差异，继而导致对政策实施效果的有偏估计。(Quantitative evaluation of policy or project implementation effect. Generally, a wide range of public policies is different from general scientific research, and it is difficult to ensure that the sample allocation for the policy implementation group and the control group is completely random. The non-randomly assigned policy implementation group and the control group are called natural trials, which have significant characteristics, i.e. there may be prior differences between the different groups of samples before the implementation of the policy, and this difference will be ignored only through a single pre-and post-comparison or horizontal comparison analysis method, which leads to the policy. Biased estimation of implementation)