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The IN= option in SAS is used when you want to match observations from one data set to another. It assigns a value of 1 to observations that match and a value of 0 to those that do not. This can be used to create a new data set that includes only those observations that match the criteria in the WHERE statement, or to create a new data set that includes the matched observations along with additional variables from the other data set.
You can use the IN= option in SAS to create a Boolean variable that indicates whether or not the current observation comes from the input dataset.
The IN= option is commonly used when you append two datasets together and you’d like to know if a particular row in the resulting dataset came from one of the specific input datasets.
The following example shows how to use the IN= option in practice.
Example: How to Use the IN= Option in SAS
Suppose we have two datasets that contain information about basketball players in the Eastern and Western conferences of the NBA:
/*create East dataset*/
data east_data;
input team $ points;
datalines;
Celtics 22
Pistons 14
Nets 35
Hornets 19
Magic 22
;
run;
/*create West dataset*/
data west_data;
input team $ points;
datalines;
Mavs 40
Rockets 39
Warriors 23
Lakers 19
Clippers 25
;
run;
/*view datasets*/
proc print data=east_data;
proc print data=west_data;
We can use the following syntax to create a new dataset that appends these two datasets together:
/*create new dataset*/
data all_data;
set east_data west_data;
run;
/*view new dataset*/
proc print data=all_data;
Notice that each row from each dataset belongs to the new dataset.
To know which dataset each row came from, we can use the IN= option as follows:
/*create new dataset*/
data all_data;
set east_data west_data(in=i);
if i then conf='West';
else conf='East';
run;
/*view new dataset*/
proc print data=all_data;
By using the IN= option, we are able to create a new column called conf that takes on a value of “East” if the row came from the dataset called east_data and a value of “West” if the row came from the dataset called west_data.
Note that we could also use only an IF statement without an ELSE statement to create a new column that simply takes on a value of * if the row came from the dataset called east_data:
/*create new dataset*/
data all_data;
set east_data(in=i) west_data;
if i then east_conf='*';
run;
/*view new dataset*/
proc print data=all_data;
By using the IN= option, we are able to create a new column called east_conf that takes on a value of * if the row came from the dataset called east_data and no value if the row came from the dataset called west_data.
The following tutorials explain how to perform other common tasks in SAS: