if和where在SAS中的区别

多谢楼主~~

厉害。学习了

搂住心细啊,

barbararan 发表于 2014-2-8 15:43
楼主这里一个问题，
data a;
input id x@@;

那是因为你在用merge合并的时候没有根据指定变量合并,你在merge语句后面加一个by id;语句就好了。

good one.

barbararan 发表于 2014-2-8 15:43
楼主这里一个问题，
data a;
input id x@@;

这里关键是要搞清楚没有by的merge是什么意思，它是one-to-one merging，而不是match-merging。 还是看原版的解释吧。注意同名变量的变量值替代。
One-to-one merging combines observations from two or more SAS data sets into a single observation in a new data set. To perform a one-to-one merge, use the MERGE statement without a BY statement. SAS combines the first observation from all data sets that are named in the MERGE statement into the first observation in the new data set, the second observation from all data sets into the second observation in the new data set, and so on. In a one-to-one merge, the number of observations in the new data set is equal to the number of observations in the largest data set named in the MERGE statement.

barbararan 发表于 2014-2-8 15:43
楼主这里一个问题，
data a;
input id x@@;

看来merge和set效果差不多，都是在编译阶段读入where

恩，不错

谢谢楼主分享，收获多多

不错，O(∩_∩)O谢谢~