Sometimes you need to reshape your data
which is in a long format (like shown below).
long famid year faminc 1 96 40000 1 97 40500 1 98 41000 2 96 45000 2 97 45400 2 98 45800 3 96 75000 3 97 76000 3 98 77000
into a wide format (like shown below).
wide1
famid faminc96 faminc97 faminc98 1 40000 40500 41000 2 45000 45400 45800 3 75000 76000 77000
Below is an example of a SAS data step
that reshapes data from a long to a wide format. In order to use this
program, you need to be able to provide some key information about your data to
be reshaped. Please note that this example (and all of the examples on
this page) assume that the values of the time variable are equally spaced (ie,
one observation per year or one observation per month). Let’s use
the examples of the long and wide1 files above
to illustrate.
You need to be able to supply 5 pieces
of information:
1. What is the name of the long data
file? LONG
2. What is the name we want for the
wide data file? We want to call the long data file WIDE1
3. What is the name of the variable
which uniquely identifies the wide observations. The wide observations are
uniquely identified by the variable FAMID
4. What is the name of the variable in
the long data file that will be used for the suffix of the wide variables (the
96 97 and 98 at the end of faminc). The 96, 97 and 98 come from the
variable YEAR.
5. What is the name of the variable to
be converted from long to wide. The variable to be converted from long to
wide is FAMINC
* read in long data ;
data long ;
INPUT famid year faminc ;
CARDS ;
1 96 40000
1 97 40500
1 98 41000
2 96 45000
2 97 45400
2 98 45800
3 96 75000
3 97 76000
3 98 77000
;
RUN ;
PROC PRINT DATA=long ;
RUN ;
* 1. Do basic long to wide ;
PROC SORT DATA=long OUT=longsort ;
BY famid ;
RUN ;
DATA wide1 ;
SET longsort ;
BY famid ;
KEEP famid faminc96 -faminc98 ;
RETAIN faminc96 - faminc98 ;
ARRAY afaminc(96:98) faminc96 - faminc98 ;
IF first.famid THEN
DO;
DO i = 96 to 98 ;
afaminc( i ) = 0 ;
END;
END;
afaminc( year ) = faminc ;
IF last.famid THEN OUTPUT ;
RUN;
* check with a basic PROC PRINT ;
PROC PRINT DATA=wide1;
RUN;
* INCLUDE PART OF THE OUTPUT ;
With only a few modifications, the data step
above can reshape two (or more) variables. Please note that you will
need to list all of the variables to be reshaped in the KEEP and RETAIN
statements, as well as having to do an array and a do-loop for each variable
to be reshaped.
* 2. To reshape data from long to wide format with 2 variables ;
DATA long2;
INPUT famid year faminc spend ;
CARDS;
1 96 40000 38000
1 97 40500 39000
1 98 41000 40000
2 96 45000 42000
2 97 45400 43000
2 98 45800 44000
3 96 75000 70000
3 97 76000 71000
3 98 77000 72000
;
RUN ;
PROC SORT DATA=long2 OUT=longsrt2 ;
BY famid ;
RUN ;
DATA wide2 ;
SET longsrt2 ;
BY famid ;
KEEP famid faminc96-faminc98 spend96-spend98 ;
RETAIN faminc96-faminc98 spend96-spend98 ;
ARRAY afaminc(96:98) faminc96-faminc98 ;
ARRAY aspend(96:98) spend96-spend98 ;
IF first.famid THEN
DO;
DO i = 96 to 98 ;
afaminc( i ) = 0 ;
aspend( i ) = 0 ;
END;
END;
afaminc( year ) = faminc ;
aspend( year ) = spend ;
IF last.famid THEN OUTPUT ;
RUN;
* check with a PROC PRINT ;
PROC PRINT DATA=wide2;
RUN;
* INCLUDE PART OF THE OUTPUT ;
Sometimes, there is no variable in the data
set that uniquely identifies each observation. Rather, two variables are
necessary to uniquely identify each observation. In this situation, you
will need to use a data step like the one shown below to reshape the data from
long to wide.
* 3. Reshaping data from long to wide format with 2 variables that identify the wide record ;
DATA long3;
INPUT famid birth age ht ;
CARDS;
1 1 1 2.8
1 1 2 3.4
1 2 1 2.9
1 2 2 3.8
1 3 1 2.2
1 3 2 2.9
2 1 1 2.0
2 1 2 3.2
2 2 1 1.8
2 2 2 2.8
2 3 1 1.9
2 3 2 2.4
3 1 1 2.2
3 1 2 3.3
3 2 1 2.3
3 2 2 3.4
3 3 1 2.1
3 3 2 2.9
;
RUN;
PROC SORT DATA=long3 OUT=longsrt3 ;
BY famid birth ;
RUN ;
DATA wide3 ;
SET longsrt3 ;
BY famid birth ;
KEEP famid ht1-ht2 ;
RETAIN ht1-ht2 ;
ARRAY aht(1:2) ht1-ht2 ;
IF first.birth THEN
DO;
DO i = 1 to 2 ;
aht( i ) = 0 ;
END;
END;
aht( age ) = ht ;
IF last.birth THEN OUTPUT ;
RUN;
* check with a PROC PRINT ;
PROC PRINT DATA=wide3;
RUN;
The following example is a more realistic
example that uses a data file having 300 records
in long format (50 wide records and 6 time points).
* 4. a more realistic example ;
* this is a more realistic data file having ;
* 300 long records (50 wide records and 6 time points);
data long4;
input id year inc ;
cards;
1 90 66483
1 91 69146
1 92 74643
1 93 79783
1 94 81710
1 95 86143
2 90 17510
2 91 17947
2 92 19484
2 93 20979
2 94 21268
2 95 22998
3 90 57947
3 91 62964
3 92 68717
3 93 70957
3 94 75198
3 95 75722
4 90 64831
4 91 71060
4 92 71918
4 93 72514
4 94 73100
4 95 74379
5 90 18904
5 91 19949
5 92 21335
5 93 22237
5 94 23829
5 95 23913
6 90 32057
6 91 34770
6 92 35834
6 93 37387
6 94 40899
6 95 42372
7 90 60551
7 91 64869
7 92 67983
7 93 70498
7 94 71253
7 95 75177
8 90 16553
8 91 18189
8 92 18349
8 93 19815
8 94 21739
8 95 22980
9 90 32611
9 91 33465
9 92 35961
9 93 36416
9 94 37183
9 95 40627
10 90 61379
10 91 66002
10 92 67936
10 93 70513
10 94 74405
10 95 76009
11 90 24065
11 91 24229
11 92 25709
11 93 26121
11 94 26617
11 95 28142
12 90 32975
12 91 36185
12 92 37601
12 93 41336
12 94 43399
12 95 43670
13 90 69548
13 91 71341
13 92 72455
13 93 76552
13 94 80538
13 95 85330
14 90 50274
14 91 53349
14 92 55900
14 93 59375
14 94 61216
14 95 63911
15 90 72011
15 91 73334
15 92 76248
15 93 77724
15 94 78638
15 95 80582
16 90 18911
16 91 20046
16 92 21343
16 93 21630
16 94 22330
16 95 23081
17 90 68841
17 91 75410
17 92 80806
17 93 81327
17 94 81571
17 95 86499
18 90 28099
18 91 30716
18 92 32986
18 93 36097
18 94 39124
18 95 39866
19 90 17302
19 91 18778
19 92 18872
19 93 19884
19 94 20665
19 95 21855
20 90 16291
20 91 16674
20 92 16770
20 93 17182
20 94 17979
20 95 18917
21 90 43244
21 91 46545
21 92 47633
21 93 50744
21 94 54734
21 95 59075
22 90 56393
22 91 59120
22 92 60801
22 93 61404
22 94 63111
22 95 69278
23 90 47347
23 91 49571
23 92 50101
23 93 51345
23 94 56463
23 95 56927
24 90 16076
24 91 17217
24 92 17296
24 93 17900
24 94 18171
24 95 18366
25 90 65906
25 91 69679
25 92 76131
25 93 77676
25 94 81980
25 95 85426
26 90 58586
26 91 61188
26 92 66542
26 93 69267
26 94 71063
26 95 74549
27 90 61674
27 91 66584
27 92 69185
27 93 75193
27 94 78647
27 95 81898
28 90 31673
28 91 31883
28 92 32774
28 93 34485
28 94 36929
28 95 39751
29 90 63412
29 91 67593
29 92 69911
29 93 73092
29 94 80105
29 95 81840
30 90 27684
30 91 28439
30 92 30861
30 93 31406
30 94 32960
30 95 35530
31 90 71873
31 91 76449
31 92 80848
31 93 88691
31 94 94149
31 95 97431
32 90 62177
32 91 63812
32 92 64235
32 93 65703
32 94 69985
32 95 71136
33 90 37684
33 91 38258
33 92 39208
33 93 39489
33 94 39745
33 95 41236
34 90 64013
34 91 66398
34 92 71877
34 93 75610
34 94 76395
34 95 79644
35 90 16011
35 91 16847
35 92 17746
35 93 19123
35 94 19183
35 95 19996
36 90 49215
36 91 52195
36 92 52343
36 93 56365
36 94 58752
36 95 59354
37 90 15774
37 91 16643
37 92 17605
37 93 18781
37 94 18996
37 95 19685
38 90 29106
38 91 31693
38 92 31852
38 93 34505
38 94 35806
38 95 36179
39 90 25147
39 91 26923
39 92 28785
39 93 30987
39 94 34036
39 95 34106
40 90 71978
40 91 79144
40 92 80453
40 93 86580
40 94 95164
40 95 96155
41 90 46166
41 91 47579
41 92 49455
41 93 53849
41 94 56630
41 95 57473
42 90 55810
42 91 59443
42 92 65291
42 93 66065
42 94 69009
42 95 74365
43 90 49642
43 91 50603
43 92 53917
43 93 54858
43 94 58470
43 95 59767
44 90 21348
44 91 22361
44 92 23412
44 93 24038
44 94 24774
44 95 25828
45 90 44361
45 91 48720
45 92 51356
45 93 54927
45 94 56670
45 95 58800
46 90 56509
46 91 60517
46 92 61532
46 93 65077
46 94 69594
46 95 73089
47 90 39097
47 91 40293
47 92 43237
47 93 44809
47 94 48782
47 95 53091
48 90 18685
48 91 19405
48 92 20165
48 93 20316
48 94 22197
48 95 23557
49 90 73103
49 91 76243
49 92 76778
49 93 82734
49 94 86279
49 95 86784
50 90 48129
50 91 49267
50 92 53799
50 93 58768
50 94 63011
50 95 66461
;
run;
PROC SORT DATA=long4 OUT=longsrt4 ;
BY id ;
RUN ;
DATA wide4 ;
SET longsrt4 ;
BY id ;
KEEP id inc90-inc95 ;
RETAIN inc90-inc95 ;
ARRAY ainc(90:95) inc90-inc95 ;
IF first.id THEN
DO;
DO i = 90 to 95 ;
ainc( i ) = 0 ;
END;
END;
ainc( year ) = inc ;
IF last.id THEN OUTPUT ;
RUN;
* verify with a PROC PRINT ;
PROC PRINT DATA=wide4(obs=5) ;
RUN;
PROC PRINT DATA=long4(obs=25) ;
RUN;
* verify with PROC MEANS ;
PROC MEANS DATA=wide4 ;
VAR inc90-inc95 ;
RUN;
PROC MEANS DATA=long4 ;
CLASS year ;
VAR inc ;
RUN;
The following example shows how to reshape
multiple variables, some of which are numeric and other that are
character (i.e., string) variables. Note that when you are identifying
the character variables in the program, you need to include a dollar sign
($). Also, within the do-loop that associates the elements of the array
with the year, you will have opening and closing quotes with nothing but a
blank space within the quotes. This is different from how the elements
of the array are associated with the year for the numeric
variables.
* 5. This example shows how to handle character variables ;
data long5;
length debt $ 3;
input famid year faminc spend debt $ ;
cards;
1 96 40000 38000 yes
1 97 40500 39000 yes
1 98 41000 40000 no
2 96 45000 42000 yes
2 97 45400 43000 no
2 98 45800 44000 no
3 96 75000 70000 no
3 97 76000 71000 no
3 98 77000 72000 no
;
run;
PROC SORT DATA=long5 OUT=long5srt ;
BY famid ;
RUN;
DATA wide5 ;
SET long5srt ;
BY famid ;
KEEP famid faminc96-faminc98 spend96-spend98 debt96-debt98 ;
RETAIN faminc96-faminc98 spend96-spend98 debt96-debt98 ;
ARRAY afaminc(96:98) faminc96-faminc98 ;
ARRAY aspend(96:98) spend96-spend98 ;
ARRAY adebt(96:98) $ 3 debt96-debt98 ;
IF first.famid THEN
DO;
DO i = 96 to 98 ;
afaminc( i ) = 0 ;
aspend( i ) = 0 ;
adebt( i ) = " " ;
END;
END;
afaminc( year ) = faminc ;
aspend( year ) = spend ;
adebt( year ) = debt ;
IF last.famid THEN OUTPUT ;
RUN;
PROC PRINT DATA=wide5 ;
RUN;