Dear Statalists,

I'd like to rearrange my data in order to analyze it.

Part of my dataset is:

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input float(fake_id match_id)
 4  33
 4 171
 4 165
 8 237
 8  97
 8 179
12  55
12 199
12  11
16  19
16 133
16 129
20  15
20  35
20 182
24 147
24  86
24 185
28  25
28 211
28   5
32 213
32  71
32  70
36  13
36  23
36 186
40  62
40  63
40 207
end

What I wan to get is something like:
id match_set
4 1
33 1
171 1
165 1
8 2
237 2
97 2
179 2
12 3
55 3
199 3
11 3
... ...
Could anyone help with this?

Thank you in advance.