Dear StataListers,

I use Stata 14.2.
Here is a simplified example of my data (three cities, three years, three variables (co, gas,waste)):

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input int(city year) byte variable_id str5 variable_id_desc float value
3101 2011 1 "co"    8919
3101 2015 2 "gas"   68.8
3101 2015 3 "waste" 54.6
3101 2015 1 "co"    7273
4416 2011 1 "co"     157
4416 2015 2 "gas"    2.2
4416 2015 3 "waste"  2.1
4416 2016 2 "gas"    3.9
4416 2016 3 "waste"  2.3
4416 2017 2 "gas"    2.3
end
I need to make this dataset "long" in a panel data format.
I tried different variants of the reshape command, but I couldn't handle it.
Could you advise how to solve this problem?