Finding Max and Storing For Each Group

[Tom Wilson]

My objective is to find the max of a certain variable for each group and then assign generate for every observation in a particular group a new variable that equals the max. So that means for every observation in the group, the max variable would have the same value.

unique_identifier group value
56 1 2048
12 1 5005
78 1 7080
46 2 9898
82 2 6568
97 2 7000

//After the code the above should look like the following:

unique_identifier group value num_max
56 1 2048 7080
12 1 5005 7080
78 1 7080 7080
46 2 9898 9898
82 2 6568 9898
97 2 7000 9898

The code I have been trying to use is the following:

summarize counter
bysort group: gen num_max = r(max)

Of course the problem with this is that r(max) is still fixed at the value of summarize, and the summarize isn't being repeated for each group.

[Nick Cox]

If there are no missings on your variable, this is the most direct way:

 
bysort group (counter) : gen num_max = counter[_N]

To ignore missings, egen is helpful:

egen num_max = max(counter), by(group)

[Collins Kipkoech]

family_no subject case mom dad first sibling last
10096802 03 0 0 1 0 0 1
10096802 01 1 0 0 1 0 0
10197151 02 0 1 0 0 0 0
10197151 01 1 0 0 1 0 0
10197151 03 0 0 1 0 0 1
I have my data in this format. I would like to generate a variable for dyads if only (case & mom) or (case and dad ) are present, a variable trio if case, mom and dad are present and a quad variable if case, mom, dad and sibling are present. The variables first and last indicate the eldset member of a family indicated by the family_no. For the variable subject 01 denotes a case, 02 a mom and 30 a dad. Please help.

[Andrew Musau]

* Example generated by -dataex-. For more info, type help dataex
clear
input long family_no byte(subject case mom dad first sibling last)
10096802 3 0 0 1 0 0 1
10096802 1 1 0 0 1 0 0
10197151 2 0 1 0 0 0 0
10197151 1 1 0 0 1 0 0
10197151 3 0 0 1 0 0 1
end

bys family_no: egen wanted1= max((case&mom)|(case&dad))
bys family_no: egen wanted2= max(case&mom&dad)

and so on. For a 0/1 variable, the condition is evaluated true if 1 and false if 0. The operator for "and" is & and "or" is |. See

help operators

Otherwise, also see https://www.stata.com/support/faqs/d...ble-recording/.


Res,:

. l, sepby(fam)

     +------------------------------------------------------------------------------------+
     | family~o   subject   case   mom   dad   first   sibling   last   wanted1   wanted2 |
     |------------------------------------------------------------------------------------|
  1. | 10096802         3      0     0     1       0         0      1         0         0 |
  2. | 10096802         1      1     0     0       1         0      0         0         0 |
     |------------------------------------------------------------------------------------|
  3. | 10197151         2      0     1     0       0         0      0         0         0 |
  4. | 10197151         1      1     0     0       1         0      0         0         0 |
  5. | 10197151         3      0     0     1       0         0      1         0         0 |
     +------------------------------------------------------------------------------------+