Interleaving: Details
Interleaving Syntax
When
you use a BY statement to concatenate data sets, the result is interleaving.
Interleaving intersperses observations from two or more data sets,
based on one or more common variables.
To interleave SAS data sets, specify
a list of data set names in the SET statement, and specify one or
more BY variables in the BY statement.
|
Syntax, DATA step for
interleaving:
DATA output-SAS-data-set;
SET SAS-data-set-1
SAS-data-set-2;
BY variable(s);
RUN;
|
Tip
Specify any number of data
sets in the SET statement. Each input data set must be sorted or indexed
in ascending order based on the BY variable or variables.
How Interleaving Selects Data
When SAS interleaves
data sets, observations in each BY group in each data set in the SET
statement are read sequentially, in the order in which the data sets
and BY variables are listed, until all observations have been processed.
The new data set includes all the variables from all the input data
sets, and it contains the total number of observations from all input
data sets.
data interlv;
set c d;
by num;
run;Figure 13.9 How Interleaving Selects Data
Example: Using Interleaving to Combine Data Sets
The following DATA step creates Clinic.Interlv by interleaving
Clinic.Therapy2012 and Clinic.Therapy2013.
data clinic.interlv; set clinic.therapy2012 clinic.therapy2013; by month; run;
Below is the listing
of Clinic.Interlv. Notice that, unlike the previous example, observations
are interleaved by month instead of being concatenated.
Figure 13.10 Example: How Interleaving Selects Data (partial output)
Last updated: January 10, 2018
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.