顶起来！

egen idcode=group( 变量)



       group(varlist) [, missing label lname(name) truncate(num)]
            may not be combined with by.  It creates one variable taking on values 1, 2, ...
            for the groups formed by varlist.  varlist may contain numeric variables, string
            variables, or a combination of the two.  The order of the groups is that of the
            sort order of varlist.  missing indicates that missing values in varlist
            (either . or "") are to be treated like any other value when assigning groups,
            instead of as missing values being assigned to the group missing.  The label
            option returns integers from 1 up according to the distinct groups of varlist in
            sorted order.  The integers are labeled with the values of varlist or the value
            labels, if they exist.  lname() specifies the name to be given to the value label
            created to hold the labels; lname() implies label.  The truncate() option
            truncates the values contributed to the label from each variable in varlist to
            the length specified by the integer argument num.  The truncate option cannot be
            used without specifying the label option.  The truncate option does not change
            the groups that are formed; it changes only their labels.

egen idcode=group(x)

谢谢楼上两位啦！原来是版主！失敬失敬！