defining group numbers

[River Huang]

Dear All, I found this question here (https://bbs.pinggu.org/thread-7407152-1-1.html). The data is

* Example generated by -dataex-. To install: ssc install dataex
clear
input float(x w)
1 1
2 1
1 2
2 2
3 2
1 3
2 3
3 3
1 4
2 4
1 5
1 6
2 6
end

We have x variable (has been sorted), and want to define the group variable like w. Any suggestions?

[Joseph Coveney]

generate long wstar = sum(x == 1)
assert wstar == w

Assumes values of x are representative, i.e., new groups all start at one.

[River Huang]

Dear Joseph, Many thanks for this wonderful suggestion.