如何从表达式中提取变量

shiyiming

例如 age~=. and age>60 从这个表达式中得到age
        age>60 and sex=1 从这个表达式得到age sex
       time1-time0>0 从这个表达式中得到time1 time0
类似这些表达式 如何通过SAS实现？谢谢！

shiyiming

SAS这个可以实现,期待高手现身....

shiyiming

好像不是很容易理解啊。

shiyiming

to stata
try perl regular expression functions in SAS

Qiong

玩不来正则~~土人土办法~~
[code:xv7tjums]data v;
length s $50.;
s="age2~=";
output;
s='_age>60 ';
output;
s='age>60 And sex=1';
output;
s='time1-time0>time24';
output;
run;

data vv;
set v;
length var $32.;
i=1;
var=scan(s,i,'-~=>< ');
do while ( compress(var)~="");
s1=upcase(substr(var,1,1));
s2=upcase(substr(var,2,1));
if ('A'<=s1<='Z' or (s1="_" and 'A'<=s2<='Z') ) and lowcase(var)  not in ('and' 'or') then output;
i=i+1;
var=scan(s,i,'-~=> ');
end;
drop s1 s2 i;
run;[/code:xv7tjums]

shiyiming

那我就来个正则表达式版本的吧..

[code:1ih262qw]data v;
        length s $50.;
        s="age2~=";
        output;
        s='_age>60 ';
        output;
        s='age>60 And sex=1';
        output;
        s='time1-time0>time24';
        output;
run;

data prx_v;
        set v;
        length v $50;
        RE = prxparse("/(\W*)(\w+)(\W*)/");
        do while (^missing(s));
                position = prxmatch(RE, s);
                if position ^= 0 then
                do;
                        call prxposn(RE, 2, start, length);
                        if start ^= 0 then v = substr(s, start, length);
                        call prxposn(RE, 3, start, length);
                        s = substr(s, start + length);
                        if lowcase(v) not in ('not', 'and', 'or', 'eq', 'ne', 'gt', 'ge', 'lt', 'le', 'in')
                        and anydigit(v) ~= 1
                        then output;
                end;
        end;
        prxfree(RE);
        keep v;
run;
[/code:1ih262qw]

shiyiming

%let aaa=age~=. and age>60; 从这个表达式中得到age
%let bbb=age>60 and sex=1 从这个表达式得到age sex
%let ccc=time1-time0>0 等
如何通过macro实现？

shiyiming

有什么好的方法通过macro实现呢