//只显示字符型变量名 string numeric int float numlist . ds,has(type string) make . retu list macros: r(varlist) : "make" ds,has(format *f) // headroom gear_ratio 显示所有带有标签的变量名 . ds,has(varlabel) make rep78 weight displacement price headroom length gear_ratio mpg trunk turn foreign 显示所有带有值标签的变量名 . ds,has(vallabel) foreign