Sum Only Certain Values in a SAS-EG Column?

[Divyaanshu8285]

How to sum only a few values in sas

Sum every 3 values leaving the first one
a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

b
sum(2,3,4)=9(in this manner)
12
15
18

Like this

[PeterClemmensen]

Do you have SAS/ETS?

[PeterClemmensen · Accepted solution]

If so, then Proc Expand is the right tool.

data have;
   do a = 1 to 20;
      output;
   end;
run;

proc expand data = have(where = (a ne 1)) out = want;
   id a;
   Convert a = b / transformout = (reverse movsum 3 reverse);
run;

Result:

a   b
2   9
3   12
4   15
5   18
6   21
7   24
8   27
9   30
10  33
11  36
12  39
13  42
14  45
15  48
16  51
17  54
18  57
19  39
20  20

[Divyaanshu8285]

Hi yes, I need a running sum...for example 

Pd

0
0.0003
0
0
0
0
0
1.25E-05
4.32E-05
4.32E-05
4.43E-05
4.43E-05
4.43E-05
0.000132
0.000132
0.000132
0.000135
0.000135
0.000134
0.000139
0.000139
0.000139
0.000142
0.000142
0.000142
0.00021
0.00021
0.00021
0.000203
0.000202
0.000202
0.000194
0.000194
0.000194
0.000185
0.000185
0.000185

leaving the first value i need sum from 2nd position to 13 position basically i need sum of 12 months pd.

Then I need sum from 3rd position to 14th position then 4th to 15th position likewise till there are less than 12 values left 

[Divyaanshu8285]

Thanks for your support!

[Tom]

Perhaps you meant SKIPPING the first one?  You don't seem to have left it as you did not include it in the output.

Let's make on input dataset named HAVE with the variable A you describe.

data have;
  do a=1 to 20;
    output;
  end;
run;

Now let's make a new dataset with the sum groups of three observations starting from the second observation.

data want;
  do n=1 to 3;
    set have(firstobs=2);
    b=sum(b,a);
  end;
  drop n;
run;

That results that differ from your example output. 9 18 27 36 45 54

So perhaps you meant something other than what you said?  Perhaps you meant you want a running sum of the last three values?

data want;
  set have;
  b + a;
  b + -lag3(a);
  if _n_ >= 4;
 * put b @;
run;

That results in the series 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57

[Divyaanshu8285]

Hi yes, I need a running sum...for example 

Pd

0
0.0003
0
0
0
0
0
1.25E-05
4.32E-05
4.32E-05
4.43E-05
4.43E-05
4.43E-05
0.000132
0.000132
0.000132
0.000135
0.000135
0.000134
0.000139
0.000139
0.000139
0.000142
0.000142
0.000142
0.00021
0.00021
0.00021
0.000203
0.000202
0.000202
0.000194
0.000194
0.000194
0.000185
0.000185
0.000185

leaving the first value i need sum from 2nd position to 13 position basically i need sum of 12 months pd.

Then I need sum from 3rd position to 14th position then 4th to 15th position likewise till there are less than 12 values left