Examples: Concatenating Data

The functional analysis of this document focuses on three main methods for concatenating SAS^© datasets. The SET statement is used to sequentially read observations from multiple input datasets into a single output dataset, appending observations one after another. PROC SQL uses the OUTER UNION CORRESPONDING clause to combine rows from two tables, superimposing common variables. Finally, PROC APPEND is used to add observations from one dataset to the end of an existing dataset, without creating a new dataset. Considerations for handling uncommon variables and using the OPEN=DEFER option are also discussed.

Data Analysis

Type : INTERNAL_CREATION

Examples use generated data (datalines) for datasets 'animal', 'plant', 'Year1', 'Year2', 'Table1', and 'Table2'.

1 Code Block

DATA STEP Data

Explanation :
This example uses the SET statement to concatenate two datasets ('animal' and 'plant') into a single output dataset ('concatenate'). Observations from 'animal' are placed before those from 'plant'. Common variables ('common') are handled, and uncommon variables are filled with missing values. The example demonstrates the creation of the 'animal' and 'plant' datasets using datalines to make them self-contained.

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1	DATA animal;
2	INPUT common $ animal$;
3	DATALINES;
4	a Ant
5	b Bird
6	c Cat
7	d Dog
8	e Eagle
9	f Frog
10	;
11	RUN;
12
13	DATA plant;
14	INPUT common $ plant$;
15	DATALINES;
16	a Apple
17	b Banana
18	c Coconut
19	d Dewberry
20	e Eggplant
21	f Fig
22	;
23	RUN;
24
25	DATA concatenate;
26	SET animal plant;
27	RUN;
28	PROC PRINT DATA=concatenate;
29	RUN;

2 Code Block

PROC SQL Data

Explanation :
This example uses PROC SQL with the OUTER UNION CORRESPONDING statement to concatenate the 'animal' and 'plant' datasets. This combines all rows from both tables and superimposes common variables. The result is stored in a new table named 'combined'. The 'animal' and 'plant' datasets are created using datalines to ensure the example's autonomy.

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1	DATA animal;
2	INPUT common $ animal$;
3	DATALINES;
4	a Ant
5	b Bird
6	c Cat
7	d Dog
8	e Eagle
9	f Frog
10	;
11	RUN;
12
13	DATA plant;
14	INPUT common $ plant$;
15	DATALINES;
16	a Apple
17	b Banana
18	c Coconut
19	d Dewberry
20	e Eggplant
21	f Fig
22	;
23	RUN;
24
25	PROC SQL;
26	create TABLE combined as
27	select * from animal
28	outer union corresponding
29	select * from plant;
30	QUIT;

3 Code Block

PROC APPEND Data

Explanation :
This example demonstrates the use of PROC APPEND to add observations from the 'Year2' dataset to the end of the 'Year1' dataset. Unlike the SET statement, PROC APPEND directly modifies the 'BASE=' dataset ('Year1' here) and does not create a new dataset. The 'Year1' and 'Year2' datasets are created with datalines.

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1	DATA Year1;
2	INPUT Date;
3	DATALINES;
4	2009
5	2010
6	2011
7	2012
8	;
9	RUN;
10
11	DATA Year2;
12	INPUT Date;
13	DATALINES;
14	2010
15	2011
16	2012
17	2013
18	2014
19	;
20	RUN;
21
22	PROC APPEND base=Year1 DATA=Year2;
23	RUN;
24	PROC PRINT DATA=Year1;
25	title "Year1";
26	RUN;

4 Code Block

DATA STEP Data

Explanation :
This example illustrates how the OPEN=DEFER option in the DATA statement can be used to generate a message in the SAS log when there are variables in the input datasets that are not present in the first dataset read. It first shows concatenation without OPEN=DEFER, where missing variables are simply filled with missing values. Then, it shows the same process with OPEN=DEFER, which results in the ignoring of additional variables and a warning in the log. The 'Table1' and 'Table2' datasets are created using datalines.

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1	DATA Table1;
2	INPUT var1 var2 var3;
3	DATALINES;
4	1 10 100
5	2 20 200
6	3 30 300
7	4 40 400
8	;
9	RUN;
10
11	DATA Table2;
12	INPUT var1 var2 var3 predict lowermean;
13	DATALINES;
14	5 50 500 0.5 0.1
15	6 60 600 0.6 0.2
16	7 70 700 0.7 0.3
17	8 80 800 0.8 0.4
18	;
19	RUN;
20
21	DATA concat;
22	SET table1 table2;
23	RUN;
24	PROC PRINT DATA=concat;
25	title "Concatenate Table1 and Table2";
26	RUN;
27
28	DATA concat2;
29	SET table1 table2 open=defer;
30	RUN;
31	PROC PRINT DATA=concat2;
32	title "Concatenate with OPEN=DEFER";
33	RUN;

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