基于其他本地的Stata本地 [英] Stata local based on other local

问题描述

我正在尝试将local与早期使用local的值一起使用.一个例子:我想定义"final"，并且我希望它包含"var1 var2".但是，我想先定义"temp"，然后在final的定义中重用其内容. 这是我尝试过的:

I am trying to use local with the value of an earlier use of local. An example: I want to define "final" and I want it to contain "var1 var2". However, I want to define "temp" first, and reuse its contents in the definition of final. Here is what I tried:

local temp "var2"

local final "var1 " `temp'

有人可以告诉我我在做什么错吗?

Can anyone tell me what I am doing wrong?

推荐答案

有效的示例:

// example data
sysuse auto, clear

// what you want
local first weight
local second `first' mpg

// example use of local second
regress price `second'

编辑

回答您的评论:

Edit

To answer your comment:

是的，您的问题是双引号.但这并不意味着使用双引号会自动给您带来麻烦.例如，这将起作用:

Yes, your problem are the double quotes. That doesn't mean, however, that using double quotes will automatically get you in trouble. For example, this will work:

// example data
sysuse auto, clear

// what you want
local first "weight"
local second "mpg  `first'"

// example use of local second
regress price `second'

此处的双引号被解释为字符串定界符，因此将被删除.在local second "mpg `first'"中(取消)引用local first时，宏替换将插入weight，而不是"weight".之后，当在regress ...中(取消)引用local second时，宏替换将导致mpg weight，而不是"mpg weight".所以这都是合法的语法.

Double quotes here are interpreted as string delimiters, and so will be stripped. When local first is (de)referenced in local second "mpg `first'", macro-substitution will insert weight, not "weight". Afterwards, when local second is (de)referenced in regress ..., macro-substitution results in mpg weight, not "mpg weight". So it's all legal syntax.

您的示例包含无效的语法.您用双引号定界第一段，然后继续另一段:

Your example contains invalid syntax. You delimit the first piece with double quotes and then continue with another piece:

`temp'

那被认为是非法的.

Stata不在乎我们是否在local语句中省略双引号，这就是为什么我的第一个示例有效.请参见 [U] 18.3.4 .宏和表达式.

Stata doesn't mind if we omit the double quotes in the local statement, which is why my first example works. See [U] 18.3.4 Macros and expressions.

另请参见 http://www.stata.com/statalist/archive/2009-01/msg00282.html 和help quotes.

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