Average value in long format and delete the duplicate to make it only 1

[Abby Chew]

How can I find the average of total_fat and mono_fat if I have data in long format and some ID appears 1 time and some appears two times. I want to have only 1 ID if the ID appears twice, I want to average it and make it appears only 1 time.


input str8 pid double(TOTAL_FAT MONO_FAT)
"01010001" 38.980000000000004 12.6
"01010001" 36.08 13.27
"01010006" 70.07000000000001 25.23
"01010006" 28.830000000000002 11.52
"01010007" 38.34 13.76

I want
01010001 37.5 12.9
01010006 39. 18
0101007 38.3. 13.76

[David Radwin]

Like this? I got a different mean value of TOTAL_FAT for pid 01010006.

. collapse (mean) TOTAL_FAT MONO_FAT, by(pid)

. list, abbrev(20) clean

            pid   TOTAL_FAT   MONO_FAT  
  1.   01010001       37.53     12.935  
  2.   01010006       49.45     18.375  
  3.   01010007       38.34      13.76