[求助]关于变量的删除

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<p>有N多个数据集，里面都有60多个变量，我要做的是：</p><p>当某个变量的前两个观测值为空值时，删除这个变量，请问有什么好的方法吗？</p><p>谢谢！</p>

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关键词：多个变量 数据集 观测值

也来看答案了

There should be easy ways, but this is the best I can come up with.

/* Assume we start with data set Original and end up with Final */
/* Generate data set containing only the first two observations */
proc sql inobs=2;
create table test as
select *
from original;
quit;

/* Use Proc Means to output the missing value of each variable */
proc means data=test noprint;
output out=test2 nmiss=/autoname;
run;

/* Transpose the form of the data set to the form we can handle */
proc transpose data=test2(drop=_TYPE_ _FREQ_) out=test3(drop=Label) NAME=Source
 LABEL=Label PREFIX=MIS;
run;
/* Get rid of the '_NMiss' at the end of the variable name to recover the original variable name */
data test4;
set test3;
 Name=trim(tranwrd(source,'_NMiss',''));
run;

/* Put the variable names in a macro, which have one or none missing value*/
proc sql noprint;
select Name into:keep separated by ' '
from test4
where mis1<2;
quit;

/* If interested, you can look at the log to see which ones were kept */
%put &keep;
/* Clean up the room */
proc datasets nolist;
delete test test1 test2 test3 test4;
run;
/* Keep only the good ones :-)*/
data final;
set original(keep=&keep);
run;

[此贴子已经被作者于2009-4-13 22:47:46编辑过]

经测试三楼的程序可运行，结果正确。

3# kunkunred
作者程序是如果该变量有2个空值，则删除该变量，不是前两个值为空则删除该变量，如果这样做之前应该把其他变量的非空值处理下

I know it looks stupid. :)


data test;
input x y z;
datalines;
. . 1
. . .
2 2 2
. 3 .
4 4 .
;
run;


data test1;
set test;
n+1;
x1=lag(x);
if (n=2 and x=. and x1=.) then x2="dele";
y1=lag(y);
if (n=2 and y=. and y1=.) then y2="dele";
z1=lag(z);
if (n=2 and z=. and z1=.) then z2="dele";
if n=2;
keep x2 y2 z2;
run;

sasa1881 发表于 2010-3-4 21:33
3# kunkunred
作者程序是如果该变量有2个空值，则删除该变量，不是前两个值为空则删除该变量，如果这样做之前应该把其他变量的非空值处理下

就抽了前2条。
有2个空值=前两个值为空。

这个方法挺不错的，学习了

失误，没注意到前面的sql...