如何跨列添加

Question

假设我有这个数据：

clear
set more off

input ///
str15(s1 s2 s3 s4)
a "b" "b" "c" 
b "b" "" "a"
c "c" "" ""
d "f" "" "g"
e "" "" ""
end

我想逐行查找跨列的非缺失值的数量。我试试：

gen sum = s1!="" + s2!="" + s3!="" + s4!=""

但这给出了类型不匹配错误。我做错了什么？

但是，我可以把它全部写出来并且有效：

gen x=s1!=""
gen y=s2!=""
gen z=s3!=""
gen q=s4!=""
gen sum1=x + y + z + q

Answer 1

我相信你想要这样的东西：

gen sum2 = !missing(s1) + !missing(s2) + !missing(s3) + !missing(s4)

或者更紧凑的东西：

 egen sum3 = rownonmiss(s1 s2 s3 s4), strok

egen 代表扩展生成，通常是开始查找的好地方，如果第一个失败则紧接着 egenmore。

但是，我不太清楚为什么您的代码会因字符串而失败。它似乎适用于数字变量。

Answer 2

问题是运算符优先级。以下作品：

gen sum = (s1!="") + (s2!="") + (s3!="") + (s4!="")

来自 Stata 用户指南

The order of evaluation (from first to last) of all operators is ! (or ~), ^, - (negation), /, *, - (subtraction), +, != (or ~=), >, <, <=, >=, ==, &, and |.

不过，我更喜欢罗伯托和迪米特里rownonmiss的推荐。

如何跨列添加

How to add across columns

stata

calculated-columns