Given the following raw data records in TEXTFILE.TXT:
----|----10---|----20---|----30
John,FEB,13,25,14,27,Final
John,MAR,26,17,29,11,23,Current
Tina,FEB,15,18,12,13,Final
Tina,MAR,29,14,19,27,20,Current
The following output is desired:
| Obs | Name | Month | Status | Week1 | Week2 | Week3 | Week4 | Week5 |
| 1 | John | FEB | Final | $13 | $25 | $14 | $27 | . |
| 2 | John | MAR | Current | $26 | $17 | $29 | $11 | $23 |
| 3 | Tina | FEB | Final | $15 | $18 | $12 | $13 | . |
| 4 | Tina | MAR | Current | $29 | $14 | $19 | $27 | $20 |
Which SAS program correctly produces the desired output?
A.
data WORK.NUMBERS;
length Name $ 4 Month $ 3 Status $ 7;
infile ‘TEXTFILE.TXT’ dsd;
input Name $ Month $;
if Month=’FEB’ then input Week1 Week2 Week3 Week4 Status $;
else if Month=’MAR’ then input Week1 Week2 Week3 Week4 Week5 Status $;
format Week1-Week5 dollar6.;
run;
proc print data=WORK.NUMBERS;
run;
B.
data WORK.NUMBERS;
length Name $ 4 Month $ 3 Status $ 7;
infile ‘TEXTFILE.TXT’ dlm=’,’ missover;
input Name $ Month $;
if Month=’FEB’ then input Week1 Week2 Week3 Week4 Status $;
else if Month=’MAR’ then input Week1 Week2 Week3 Week4 Week5 Status $;
format Week1-Week5 dollar6.;
run;
proc print data=WORK.NUMBERS;
run;
C.
data WORK.NUMBERS;
length Name $ 4 Month $ 3 Status $ 7;
infile ‘TEXTFILE.TXT’ dlm=’,’;
input Name $ Month $ @;
if Month=’FEB’ then input Week1 Week2 Week3 Week4 Status $;
else if Month=’MAR’ then input Week1 Week2 Week3 Week4 Week5 Status $;
format Week1-Week5 dollar6.;
run;
proc print data=WORK.NUMBERS;
run;
D.
data WORK.NUMBERS;
length Name $ 4 Month $ 3 Status $ 7;
infile ‘TEXTFILE.TXT’ dsd @;
input Name $ Month $;
if Month=’FEB’ then input Week1 Week2 Week3 Week4 Status $;
else if Month=’MAR’ then input Week1 Week2 Week3 Week4 Week5 Status $;
format Week1-Week5 dollar6.;
run;
proc print data=WORK.NUMBERS;
run;
Check Answer注解：
DSD：默认“,”为分隔符，将2个连续的分隔符视为一个missing value。比如将数据“a,b,,d”视为：’a’ ‘b’ missing value ‘d’
DLM：等价于DELIMITER，用于替换默认分隔符（空格）。比如DLM=’*’，将分隔符由空格替换成‘*’
MISSOVER：如果一行数据中的数据个数少于需要定义的变量数量，MISSOVER将防止SAS去下一行寻找数据，并将多出来的变量的值设为missing。比如，一行数据中仅有3个数据“a,b,c”，但INPUT中定义了4个变量（variable1-variable4）。如果没有MISSOVER，SAS会去新的一行寻找数据并为variable4赋值。加上MISSOVER，SAS就不会去下一行，而是将variable4的值设为missing。
@：默认情况下，每出现一次INPUT，SAS都会去新的一行读取数据，而@的作用是让SAS继续在当前行读取数据。比如这个例子：
data d1;
input v1 $ v2 $ @;
input v3 $ v4 $;
datalines;
a b c d
e f g h
;
run;
有@的输出为：
| Obs | v1 | v2 | v3 | v4 |
| 1 | a | b | c | d |
| 2 | e | f | g | h |
去掉@则为：
| Obs | v1 | v2 | v3 | v4 |
| 1 | a | b | e | f |
与@类似的还有@@。区别在于，在同一个DATA步骤中阻止换行用@，而在不同的DATA步骤中则用@@。何为同一DATA步骤？上面这个例子中，声明了4个变量，那么定义一遍v1, v2, v3, v4为一个DATA步骤。下面举一个使用@@的例子：
data d2;
input v1 $ v2 $ @@;
datalines;
a b c d
;
run;
这个例子中定义一遍v1, v2为一个DATA步骤，@@能够阻止SAS在下一个DATA步骤中去新的一行读取数据。
有@@输出的结果为：
| Obs | v1 | v2 |
| 1 | a | b |
| 2 | c | d |
不使用@或仅使用一个@的输出结果为：
| Obs | v1 | v2 |
| 1 | a | b |
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