向下填充在SAS

Question

有條件的空值如何填寫擊落空值不同的組。 我的數據是這樣的：

id visit status var reason 
1 1  Done  x1 
1 1  Done  x2 
1 1  Done  x3 
1 2  Not Done x1 text1 
1 2  Not Done x2 
1 2  Not Done x3 
1 3  Done  x1 
1 3  Done  x2 
1 3  Done  x3 
2 1  Not Done x1 text2 
2 1  Not Done x2 
2 1  Not Done x3 
2 2  Done  x1 
2 2  Done  x2 
2 2  Done  x3 
2 3  Done  x1 
2 3  Done  x2 
2 3  Done  x3 

輸出應該是這樣的

id visit status var reason 
1 1  Done  x1 
1 1  Done  x2 
1 1  Done  x3 
1 2  Not Done x1 text1 
1 2  Not Done x2 text1 
1 2  Not Done x3 text1 
1 3  Done  x1 
1 3  Done  x2 
1 3  Done  x3 
2 1  Not Done x1 text2 
2 1  Not Done x2 text2 
2 1  Not Done x3 text2 
2 2  Done  x1 
2 2  Done  x2 
2 2  Done  x3 
2 3  Done  x1 
2 3  Done  x2 
2 3  Done  x3 

我覺得這是一個很簡單的問題，但現在，我一直沒能解決這個問題。任何幫助將不勝感激！

Answer 1

這是一個簡單的任務，在使用by語句時，利用數據步驟中存在的first.variable功能。

基本上我已經創建每當遇到新的訪問分配原因的值的新變量。 retain語句確保爲ID和訪問不更改的所有後續行復制新變量值。然後我只刪除原來的Reason變量並重新命名新的變量。

data have; 
infile datalines dsd; 
input id visit status &$ var $ reason $; 
datalines; 
1, 1,  Done,  x1,, 
1, 1,  Done,  x2,, 
1, 1,  Done,  x3,, 
1, 2,  Not Done, x1, text1, 
1, 2,  Not Done, x2,, 
1, 2,  Not Done, x3,, 
1, 3,  Done,  x1,, 
1, 3,  Done,  x2,, 
1, 3,  Done,  x3,, 
2, 1,  Not Done, x1, text2, 
2, 1,  Not Done, x2,, 
2, 1,  Not Done, x3,, 
2, 2,  Done,  x1,, 
2, 2,  Done,  x2,, 
2, 2,  Done,  x3,, 
2, 3,  Done,  x1,, 
2, 3,  Done,  x2,, 
2, 3,  Done,  x3 
; 
run; 

data want; 
set have; 
retain reason_new; 
by id visit; 
if first.visit then reason_new=reason; 
drop reason; 
rename reason_new = reason; 
run;