Is there any way to DEgroup a variable?

[Daniel Abib]

Sorry for the confusing title, by DEgroup I mean that I created a group, which is a variable that assumes values from 1 to N, and I want to recover the original variable.
Is there a way to recover the original variable the group was created from?
Example:

ym
20081
20082
20083

egen time=group(ym) will generate

time
1
2
3

Is there a way to recover ym from time?

[Nick Cox]

No; but you have the original variable unless you dropped it.