topic Re: Merging questions in SAS Programming

Merging questions

michan22 — Sat, 26 May 2018 00:37:15 GMT

Hi SAS experts,

I have a question regards merging datasets.

dataset1 have one observation for each subject (total subject #=60,000):

subjectid registration_date age gender weight

1 5/20/1990 45 M 180

2 4/23/1995 50 M 160

3 3/2/1992 33 F 130

5 6/5/1990 65 F 150

....

dataset2 have multiple observations for each subject:

subjectid testdate test1 test2 test3

1 5/21/1990 50 40 40

1 6/4/1992 45 78 45

3 4/25/1996 45 23 34

3 8/5/1998 45 56 77

3 9/3/1999 12 12 67

4 4/1/1990 23 24 23

4 6/5/1990 23 23 25

....

dataset1 has subjects that are not in dataset2 and vice versa.

I wanted to distinguish date type (registration_date or test_date) so I created new variables date1 (which equals to registration_date in dataset1 and testdate in dataset2) and datetype (which equals to "registration" in dataset1 and "test" in dataset2).

Then I merged the 2 datasets by subjectid and date1, and the merged dataset looked like this:

subjectid date1 datetype registration_date age gender weight testdate test1 test2 test3

1 5/20/1990 registration 5/20/1990 45 M 180

1 5/21/1990 test 5/21/1990 50 40 40

1 6/4/1992 test 6/4/1992 45 78 45

2 4/23/1995 registration 4/23/1995 50 M 160

3 3/2/1992 registration 3/2/1992 33 F 130

3 4/25/1996 test 4/25/1996 45 23 34

3 8/5/1998 test 8/5/1998 45 56 77

3 9/3/1999 test 9/3/1999 12 12 67

4 4/1/1990 test 4/1/1990 23 24 23

4 6/5/1990 test 6/5/1990 23 23 25

5 6/5/1990 registration 6/5/1990 65 F 150

.....

Now I need to exclude patients who only appear in dataset2 and not in dataset1 (so merged dataset will not have subject 4....).

I tried the in operator but I must not have the syntax right because it did not come out the way I want it to.

Please help and thank you very much in advance for any advice!

Re: Merging questions

Reeza — Sat, 26 May 2018 00:53:55 GMT

Please show us your current merge code so we can suggest how to modify it. For starters, did you use SQL or a data step?

IN data set option (not operator) in a data step should work as expected, assuming it was implemented correctly.

data merged;
merge a (in=inA) b (in=inB);
by ID date;

if inA; *keeps only records that are in A;

run;

@michan22 wrote:

Hi SAS experts,

I have a question regards merging datasets.

dataset1 have one observation for each subject (total subject #=60,000):

subjectid registration_date age gender weight

1 5/20/1990 45 M 180

2 4/23/1995 50 M 160

3 3/2/1992 33 F 130

5 6/5/1990 65 F 150

....

dataset2 have multiple observations for each subject:

subjectid testdate test1 test2 test3

1 5/21/1990 50 40 40

1 6/4/1992 45 78 45

3 4/25/1996 45 23 34

3 8/5/1998 45 56 77

3 9/3/1999 12 12 67

4 4/1/1990 23 24 23

4 6/5/1990 23 23 25

....

dataset1 has subjects that are not in dataset2 and vice versa.

I wanted to distinguish date type (registration_date or test_date) so I created new variables date1 (which equals to registration_date in dataset1 and testdate in dataset2) and datetype (which equals to "registration" in dataset1 and "test" in dataset2).

Then I merged the 2 datasets by subjectid and date1, and the merged dataset looked like this:

subjectid date1 datetype registration_date age gender weight testdate test1 test2 test3

1 5/20/1990 registration 5/20/1990   45 M 180

1   5/21/1990 test 5/21/1990   50 40 40

1   6/4/1992 test   6/4/1992 45 78 45

2 4/23/1995 registration 4/23/1995 50 M 160

3 3/2/1992 registration 3/2/1992 33 F 130

3   4/25/1996 test   4/25/1996 45 23 34

3   8/5/1998 test   8/5/1998 45 56 77

3   9/3/1999 test   9/3/1999 12 12 67

4   4/1/1990 test   4/1/1990 23 24 23

4   6/5/1990 test   6/5/1990 23 23 25

5   6/5/1990 registration 6/5/1990 65 F 150

.....

Now I need to exclude patients who only appear in dataset2 and not in dataset1 (so merged dataset will not have subject 4....).

I tried the in operator but I must not have the syntax right because it did not come out the way I want it to.

Please help and thank you very much in advance for any advice!

Re: Merging questions

SuryaKiran — Sat, 26 May 2018 01:28:53 GMT

You might be looking for a left join.

....................
FROM Dataset1
LEFT JOIN Dataset2 ON ........

Show us the code you assist you more in detail.

Re: Merging questions

michan22 — Sat, 26 May 2018 20:58:32 GMT

Hi!

My code right now:

data merge_nodup_droplabonly;

format subjectid $9. date1 mmddyy10.;

merge dataset1 (in=a) artdate tbdate hivdate clinicalnodup dataset2 (in=b drop=_name_);

by subjectid date1;

run;

I tried if a, if a=1, and it only kept one data line per subject, which is not what I want.

Thank you!!

Re: Merging questions

michan22 — Sat, 26 May 2018 21:17:49 GMT

So I actually found a solution...

Created another dataset that tagged every subject in dataset1, and combined this dataset with the previously merged dataset and deleted anyone without the tag.

I know this is probably not the smartest or cleanest way to do this, so any other suggestions are appreciated!!

Thank you all!!

Re: Merging questions

Patrick — Sun, 27 May 2018 10:03:16 GMT

@michan22

Why wouldn't below simple merge not work for you?

data merged;
  merge dataset1 (in=ds1) dataset2 (in=ds2);
  by subjectid;
  if ds1; *keeps only records that are in dataset1;
run;