//原数据状态
des
// Contains data from D:\Stata17\ado\base/a/auto.dta
// Observations: 74 1978 automobile data
// Variables: 12 13 Apr 2020 17:45
// (_dta has notes)
// --------------------------------------------------------------------------------
// Variable Storage Display Value
// name type format label Variable label
// --------------------------------------------------------------------------------
// make str18 %-18s Make and model
// price int %8.0gc Price
// mpg int %8.0g Mileage (mpg)
// rep78 int %8.0g Repair record 1978
// headroom float %6.1f Headroom (in.)
// trunk int %8.0g Trunk space (cu. ft.)
// weight int %8.0gc Weight (lbs.)
// length int %8.0g Length (in.)
// turn int %8.0g Turn circle (ft.)
// displacement int %8.0g Displacement (cu. in.)
// gear_ratio float %6.2f Gear ratio
// foreign byte %8.0g origin Car origin
// --------------------------------------------------------------------------------
// Sorted by: foreign
list make in 1/5
//
// +---------------+
// | make |
// |---------------|
// 1. | AMC Concord |
// 2. | AMC Pacer |
// 3. | AMC Spirit |
// 4. | Buick Century |
// 5. | Buick Electra |
// +---------------+
//encode 命令可以将字符型变量转换为数值型变量。具体地，将字符变量的不同取值，按照字母排列顺序分别映射到数值 1, 2,...，并为生成的数字变量添加值标签。
encode make ,gen(numvar)
//结果体现：
list numvar in 1/5,nolabel
//
// +--------+
// | numvar |
// |--------|
// 1. | 1 |
// 2. | 2 |
// 3. | 3 |
// 4. | 7 |
// 5. | 8 |
// +--------+
list numvar in 1/5
//
// +---------------+
// | numvar |
// |---------------|
// 1. | AMC Concord |
// 2. | AMC Pacer |
// 3. | AMC Spirit |
// 4. | Buick Century |
// 5. | Buick Electra |
// +---------------+
