Conditionally Processing Observations from Multiple SAS Data Sets

Combining Selected Observations from Multiple Data Sets

To create a data set that contains only the observations that are selected according to a particular criterion, you can use the subsetting IF statement and a SET statement that specifies multiple data sets. The following DATA step reads two input data sets to create a combined data set that lists only the winning teams:

data champions(drop=result);1 
   set southamerican (in=S) european;2 
   by Year;
   if result='won';3 
   if S then Continent='South America';4 
   else Continent='Europe';
run;

proc print data=champions;
   title 'World Cup Champions from 1954 to 1998';
   title2 'including Countries'' Continent';
run;

The following list corresponds to the numbered items in the preceding program:

	The DROP= data set option drops the variable Result from the new data set CHAMPIONS because all values for this variable will be the same.
	The SET statement reads observations from two data sets: SOUTHAMERICAN and EUROPEAN. The S= data option creates the variable S which is set to 1 each time an observation is contributed by the SOUTHAMERICAN data set.
	A subsetting IF statement writes the observation to the output data set CHAMPIONS only if the value of the Result variable is won.
	When the current observation comes from the data set SOUTHAMERICAN, the value of S is 1. Otherwise, the value is 0. The IF-THEN/ELSE statements execute one of two assignment statements, depending on the value of S. If the observation comes from the data set SOUTHAMERICAN, then the value assigned to Continent is South America. If the observation comes from the data set EUROPEAN, then the value assigned to Continent is Europe.

The following output shows the resulting data set CHAMPIONS:

Combining Selected Observations

                     World Cup Champions from 1954 to 1998                     2
                         including Countries' Continent

             Obs    Year    Country         Score    Continent

               1    1954    West Germany     3-2     Europe       
               2    1958    Brazil           5-2     South America
               3    1962    Brazil           3-1     South America
               4    1966    England          4-2     Europe       
               5    1970    Brazil           4-1     South America
               6    1974    West Germany     2-1     Europe       
               7    1978    Argentina        3-1     South America
               8    1982    Italy            3-1     Europe       
               9    1986    Argentina        3-2     South America
              10    1990    West Germany     1-0     Europe       
              11    1994    Brazil           3-2     South America
              12    1998    France           3-0     Europe

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