Coursera-DataScience-3:为了不丢失课堂作业，无论我在哪里工作

项目 - 获取和清理数据 该代码假设项目数据已从下载并解压到工作目录中。 “run_analysis.R”脚本以下列方式运行： 1. Loads and merges train and test data for X, Y, and Subject 2. Labels the X columns by using the included features.txt file 3. Selects only columns that contain mean() or std() using grepl() 4. Uses a data.frame selection trick to merge the label names for activities 5. Names the rest of the columns that have not already been nam