Question

身份证号码6回报＆＃39;体重不足＆＃39;什么时候应该回归'超重＆＃39; 有问题的代码行，第30-53行，包含嵌套的if语句，并产生一个不良结果。这些方法的目的是将样本分为权重类别：体重不足，平均或超重。

TITLE 'A SHORT SAS PROGRAM';
OPTIONS LS=72;
* Create data file with height and weight data;

DATA HTWT;
    INPUT ID GENDER $ HEIGHT WEIGHT;
    DATALINES;
1 M 68.5 155.0
2 F 61.2 99.00
3 F 63.0 115.0
4 M 70.0 205.0
5 M 68.6 170.0
6 F 65.1 125.0
7 M 72.4 220.0
;
    * Create a new categorical variable for height;

DATA HTWT;
    SET work.HTWT;

    IF HEIGHT < 68 THEN
        STATURE='Short';

    IF HEIGHT >=68 THEN
        STATURE='Tall';
RUN;

* Create a new categorical variable for weight;

DATA HTWT;
    SET work.HTWT;

    IF GENDER='M' THEN
        IF WEIGHT > 170 THEN
            WEIGHT_CLASS='Overweight';

        IF 170 >=WEIGHT >=150 THEN
            WEIGHT_CLASS='Average';

        IF WEIGHT < 140 THEN
            WEIGHT_CLASS='Underweight';

        ELSE IF GENDER='F' THEN
            IF WEIGHT > 120 THEN
                WEIGHT_CLASS='Overweight';

            IF 120 >=WEIGHT >=100 THEN
                WEIGHT_CLASS='Average';

            IF WEIGHT < 100 THEN
                WEIGHT_CLASS='Underweight';
        RUN;

        * Changing units of height from inches to centimeters;

        DATA HTWT;
            SET work.HTWT;
            HEIGHT=2.54 * HEIGHT;
        RUN;

        * Creates HEALTH_INDEX;

        DATA HTWT;
            SET work.HTWT;
            HEALTH_INDEX=WEIGHT/HEIGHT;
        RUN;

        * Print the data file HTWT;

        PROC PRINT DATA=HTWT;
            TITLE 'HEIGHT AND WEIGHT DATA';
        RUN;

        * Sorts the data by gender. Some procedures require sorted data;

        PROC SORT DATA=HTWT OUT=sorted;
            BY GENDER;
        RUN;

        * Print the sorted data file;

        PROC PRINT DATA=sorted;
            TITLE 'GENDER SORTED HTWT DATA';
        RUN;

Answer 1

将嵌套的if语句修改为：

 IF  GENDER='M' THEN do;
     IF WEIGHT > 170 THEN
        WEIGHT_CLASS='Overweight';

    else if 150 <= Weight <= 170 THEN
        WEIGHT_CLASS='Average';

    else
        WEIGHT_CLASS='Underweight';
    end;

 else do;
    IF WEIGHT > 120 THEN
        WEIGHT_CLASS='Overweight';

    else iF 100 <= Weight =< 120 THEN
        WEIGHT_CLASS='Average';

    else
        WEIGHT_CLASS='Underweight';
 end;

看看它是否有效？

Answer 2

请不要接受我的答案作为正确答案，因为我迟到了，而且普遍的答案是明确和有用的。但是我在这里给你一个简单的建议，当你必须连接很多嵌套的if语句时，请使用select when语句（来自sql语言）为所有可能变量的值提供一个层。

data want;
set have;
if gender='M' then do;
select (weight);
   when (>x) weight_class='';
   when (<y) weight_class='';
   otherwise weight_class=''
end;
end;
else if gender='F' then do;
select (weight);
   when (>x) weight_class='';
   when (<y) weight_class='';
   otherwise weight_class=''
end;
end;
run;

Answer 3

按顺序处理连续的IF语句。因此，最后一个是测试WEIGHT是否＆lt;当然，第6号当然是6号被列为体重不足。如果要控制执行顺序，请添加一些ELSE和/或DO / END块。你的基本结构可能应该是这样的。

if A then do;
  if B then xxx ;
  else if C then xxx ;
  else if D then xxxx ;
end;

Answer 4

如果语句有用，但有时创建格式并使用put语句来执行分配更安全。如果你不得不做很多IF，尤其如此，至少在我的情况下，我做的打字越多，我搞砸的机会就越大。

使用put语句的代码更容易检查和维护。

SAS嵌套如果语句产生不正确的结果

4 个答案: