ValueError: Boolean value of Quantity with offset unit is ambiguous.

[afrazahmad21]

# Temperature
T = 35 * u.degC

print(type(T))
# Pressure (from operation data)
P = 101.325 * u.kPa  # 1 atp

print(P)
# Duty flow rate
Q = 0.007165 * u.m ** 3 / u.sec  # equivalent to 429.91 L/min

# Fluid property (from operation data)
fluid = Stream('water', T=T, P=P, Q=Q)

Pint version = 0.15

Error StackTrace

Traceback (most recent call last):
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/Modules/CalculationSheet/sanjel/DashboardTable/PumpEfficiency.py", line 204, in
fluid = Stream('water', T=T, P=P, Q=Q)
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/thermo/stream.py", line 215, in init
T=T, P=P, Vf_TP=V_TP)
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/thermo/mixture.py", line 451, in init
self.Chemicals = [Chemical(component, P=P, T=T) for component in self.components]
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/thermo/mixture.py", line 451, in
self.Chemicals = [Chemical(component, P=P, T=T) for component in self.components]
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/thermo/chemical.py", line 578, in init
self.calculate(T, P)
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/thermo/chemical.py", line 587, in calculate
if T:
File "/home/afraz/Desktop/IPMS-PYTHON/IPMS-API/venv/lib/python3.7/site-packages/pint/quantity.py", line 1556, in bool
raise ValueError("Boolean value of Quantity with offset unit is ambiguous.")
ValueError: Boolean value of Quantity with offset unit is ambiguous.

[dopplershift]

I'm not sure this is a bug. The problem is, with an offset unit, it's not clear what the right answer is. Let's take the example of 0 degrees Celsius. Being zero, this could reasonably be considered False. If you convert to Kelvin, this is now 273.15 and would be True.

[jthielen]

This is intentional behavior, and not a bug. See: #866 and #965