Generate variable with multiple constraints

[Pippa Lange]

Hi there,
I am trying to generate these charge, outage and spillover variables.
I have a battery with size 50 and it starts off fully charged. When net demand is negative it is charging the battery although it can't be charged over 50. When net demand is positive it discharges but can't go below 0. I can't seem to generate a charge variable that is the previous value less net demand constrained within 50>charge>0 let alone have it prompt an outage or spillover record. I have some example values below, thanks in advance!

Net Demand	Charge	Outage	Spillover
-12	50		12
-8	50		8
12	38
24	14
15	0	-1
-10	10
-22	32
-20	50		2

[Nick Cox]

This may help.

* Example generated by -dataex-. For more info, type help dataex
clear
input byte(netdemand charge)
-12 50
 -8 50
 12 38
 24 14
 15  0
-10 10
-22 32
-20 50
end

gen wanted = 50 in 1
replace wanted = cond(wanted[_n-1] - netdemand < 0, 0, min(50, wanted[_n-1] - netdemand)) in 2/L

list, sep(0)

     +----------------------------+
     | netdem~d   charge   wanted |
     |----------------------------|
  1. |      -12       50       50 |
  2. |       -8       50       50 |
  3. |       12       38       38 |
  4. |       24       14       14 |
  5. |       15        0        0 |
  6. |      -10       10       10 |
  7. |      -22       32       32 |
  8. |      -20       50       50 |
     +----------------------------+