SAS Data Step 4 Combine Datasets.ppt

* SAS looks at the first BY group in each data set to determine which BY group should appear first. In this case, the first BY group, observations with the value 1 for variable ID, is the same in both data sets. SAS reads and copies the first observation from dataset A into the PDV, as the next figure illustrates. 怀灸柜内媚葵卑黑说捌捆恢雌惦逃栽撤运熙眷盔论溺贤江葵役傻造猴啼赠SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * DATA c; MERGE a b; BY id; RUN; ... PDV Match Merge -- Example Execute A _N_ _ERROR_ ID A B first.ID last.ID 1 0 1 0 1 A1 嘛译轨译训拔沁甭冗磷碟送柔批捎赤币掂印赣嘿摧犬筛析功嚎醒镀氛忽督SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * SAS reads and copies the first observation from B into the PDV, as the next figure illustrates. If a data set does not have any observations in a BY group, then the program data vector contains missing values for the variables that are unique to that data set. 道娄拿纶刘加绚彝布蜂迹楞蛙南羞郝另没酥团邻让昂爽陪命淌撰枣襟腰详SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * DATA c; MERGE a b; BY id; RUN; ... PDV Match Merge -- Example B _N_ _ERROR_ ID A B first.ID last.ID 1 0 1 0 1 A1 B1 生尝胖衔旗衡昆趟掌肢都伞心菌柜磐杨挺愤躯寓丽督腆斌帐班壤绩钒革广SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * SAS writes the observation to the new data set and retains the values in the PDV. (If the PDV contained variables created by the DATA step, then SAS would set them to missing after writing to the new data set.) 红屹驾换旋矾渝蜒释悦元炉菲桐氯桐武拭莲婆寝龋猛仑贯面阵习戒丽圆衅SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * DATA c; MERGE a b; BY id; RUN; ... PDV Match Merge -- Example B _N_ _ERROR_ ID A B first.ID last.ID 1 0 1 0 1 A1 B1 Output to dataset C 躬堪餐痴匝喂萌输寨谊铡遏瘴颁剔萌训吓臣拈萨亚匆索编昼剑露障关侣腋SAS Data Step 4 Combine DatasetsSAS Data Step 4 Combine Datasets * SAS looks for a second observation in the BY group in each data set. Dataset A still has one; dataset B does not. The MERGE statement reads the second observation in the BY group from dataset A. Because dat