热度 6||
clonevar — Clone existing variable
在Stata中一提到新建变量,一般大家最先想到的是generate命令,但有时候我们需要新建一个和旧变量的结构一模一样的变量,这个时候clonevar命令就粉墨登场了,顾名思义clonevar可以克隆变量,包括变量的存储类型、变量值、显示格式、变量标签、变量值标签、注释和特征。
clonevar命令的一般语句:clonevar newvar = varname;clonevar命令的菜单使用方法:Data > Create or change data > Other variable-creation commands > Clone existing variable。
实例(命令前的.不用输入,/**/之间的是程序注释):
. webuse travel, clear /*从Stata网站读取数据travel*/
. describe mode /*察看变量mode的格式*/
storage display value
variable name type format label variable label
----------------------------------------------------------------------------------------------------
mode byte %8.0g travel travel mode alternatives
. label list travel /*察看标签travel的值*/
travel:
1 air
2 train
3 bus
4 car
. clonevar airtrain = mode if mode==1 | mode==2 /*当mode为air或train时,从mode克隆新变量airtrain*/
(420 missing values generated)
. clonevar airtrain2 = mode if mode=="air":travel | mode=="train":travel /*另一种方式,直接调用标签,更直观*/
(420 missing values generated)
. describe mode airtrain airtrain2 /*查看mode和其克隆变量的格式*/
storage display value
variable name type format label variable label
----------------------------------------------------------------------------------------------------
mode byte %8.0g travel travel mode alternatives
airtrain byte %8.0g travel travel mode alternatives
airtrain2 byte %8.0g travel travel mode alternatives
. list mode airtrain airtrain2 in 1/5 /*查看看mode和其克隆变量的前5条记录*/
+-----------------------------+
mode airtrain airtra~2
-----------------------------
1. air air air
2. train train train
3. bus . .
4. car . .
5. air air air
+-----------------------------+
软件传送门:Stata 12 SE 绿色版及使用手册(共17本)
http://www.epiman.cn/thread-33102-1-1.html
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