介绍 这是Coursera课程第4周的“获取和清洁数据”最终项目。 该项目解决了5个问题: 1. Merges the training and the test sets to create one data set. 2. Extracts only the measurements on the mean and standard deviation for each measurement. 3. Uses descriptive activity names to name the activities in the data set 4. Appropriately labels