Simplify component/connection property value check

[HaSchneider]

It annoys me to have to type._val each time I just want to get a component property for debugging or whatevver.
I would appreciate when I could get the value as pint quantity just by writting (like it is the case for property decorated methods):
my_connection.T

As the datacontainer should be revised anyway, this might be a good moment to think about such a feature.
A first quite simple idea is to add a __repr__() dunder method to the corresponding datacontainers, returning the ._val property:

class FluidProperties(_NumEqMixin, DataContainer):
    #...
    def __repr__(self):
        return f'{self._val}'

I already tested it and it works, it just might confuse people, as it seems to return the value, but it is actually still the object and just prints the value.

[fwitte]

I think that is a nice idea, I already thought about similar here #796.

I already tested it and it works, it just might confuse people, as it seems to return the value, but it is actually still the object and just prints the value.

This is a really valid point, that was something which has confused me in the past as well :D

What about something like this:

print("=" * 60)
print("before solving")
print("=" * 60)
print(repr(c1))
print()
print(c1)
print()
print(c2)
print()
print(va)

nw.solve("design")

print()
print("=" * 60)
print("after solving")
print("=" * 60)
print(c1)
print()
print(c2)
print()
print(va)
print()
print("single data containers")
print("-" * 60)
print("print(c1.T):")
print(c1.T)
print()
print("print(c1.fluid):")
print(c1.fluid)
print()
print("repr(c1.T):   ", repr(c1.T))
print("repr(c1.fluid):", repr(c1.fluid))
print("repr(va.pr):  ", repr(va.pr))
print()
print("connection with a four component mixture")
print("-" * 60)
air_so = Source("air source")
air_si = Sink("air sink")
c3 = Connection(air_so, "out1", air_si, "in1", label="air")
c3.set_attr(
    m=1.2,
    fluid={"N2": 0.7551, "O2": 0.2314, "Ar": 0.0129, "CO2": 0.0006}
)
print(c3)
print()
print("print(c3.fluid):")
print(c3.fluid)

============================================================
before solving
============================================================
Connection('1', source:out1 -> expansion valve:in1)

Connection: 1 (source:out1 -> expansion valve:in1)

property      value  unit  SI value  spec
----------  -------  ----  --------  ----
m            3.6000             nan  set
p           16.0000             nan  set
T           95.3000             nan  set
fluid[NH3]   1.0000                  set

Connection: 2 (expansion valve:out1 -> sink:in1)

property             value  unit  SI value  spec
--------  ----------------  ----  --------  ----
p_ref     0.5 * p('1') + 0                  set

Valve: expansion valve
no specifications or results

============================================================
after solving
============================================================
Connection: 1 (source:out1 -> expansion valve:in1)

property        value  unit           SI value  spec
----------  ---------  ----------  -----------  ----
m              3.6000  kg / s       3.6000e+00  set
p             16.0000  bar          1.6000e+06  set
h           1797.2835  kJ / kg      1.7973e+06
T             95.3000  °C           3.6845e+02  set
T_bubble      41.0430  °C           3.1419e+02
T_dew         41.0430  °C           3.1419e+02
v              0.3730  m3 / s       3.7301e-01
x              1.0000               1.0000e+00
td_dew        54.2570  Δ°C          5.4257e+01
td_bubble    -54.2570  Δ°C         -5.4257e+01
vol            0.1036  m3 / kg      1.0361e-01
s           6103.0951  J / K / kg   6.1031e+03
fluid[NH3]     1.0000                           set

Connection: 2 (expansion valve:out1 -> sink:in1)

property               value  unit           SI value  spec
----------  ----------------  ----------  -----------  ----
m                     3.6000  kg / s       3.6000e+00
p                     8.0000  bar          8.0000e+05
h                  1797.2835  kJ / kg      1.7973e+06
T                    84.1502  °C           3.5730e+02
T_bubble             17.8634  °C           2.9101e+02
T_dew                17.8634  °C           2.9101e+02
v                     0.7514  m3 / s       7.5142e-01
x                     1.0000               1.0000e+00
td_dew               66.2868  Δ°C          6.6287e+01
td_bubble           -66.2868  Δ°C         -6.6287e+01
p_ref       0.5 * p('1') + 0                           set
vol                   0.2087  m3 / kg      2.0873e-01
s                  6421.5284  J / K / kg   6.4215e+03
fluid[NH3]            1.0000

Valve: expansion valve

parameter       value  unit    SI value  spec
---------  ----------  ----  ----------  ----
pr             0.5000        5.0000e-01
dp             8.0000  bar   8.0000e+05
zeta_d4    4.8763e+05        4.8763e+05
zeta       4.8763e+05        4.8763e+05

single data containers
------------------------------------------------------------
print(c1.T):
  value  unit    SI value  spec
-------  ----  ----------  ----
95.3000  °C    3.6845e+02  set

print(c1.fluid):
fluid  mass fraction  spec
-----  -------------  ----
NH3           1.0000  set

repr(c1.T):    FluidProperties(val=95.3, unit='°C', val_SI=368.45, is_set=True)
repr(c1.fluid): FluidComposition(val={'NH3': 1.0}, is_set=['NH3'])
repr(va.pr):   ComponentProperties(val=0.5, unit='', val_SI=0.5, is_set=False, is_var=False)

connection with a four component mixture
------------------------------------------------------------
Connection: air (air source:out1 -> air sink:in1)

property     value  unit  SI value  spec
----------  ------  ----  --------  ----
m           1.2000             nan  set
fluid[N2]   0.7551                  set
fluid[O2]   0.2314                  set
fluid[Ar]   0.0129                  set
fluid[CO2]  0.0006                  set

print(c3.fluid):
fluid  mass fraction  spec
-----  -------------  ----
N2            0.7551  set
O2            0.2314  set
Ar            0.0129  set
CO2           0.0006  set

[HaSchneider]

Ah, yes that looks nice. By the advanced formatting of the printouts it is clear, that it is just a printout.
One minor comment: For me the printouts of the connection and components are too extensive and clutter up my terminal/jupyter notebook too much. When I want to print the basic connection information, the info about label, source and target are enough. An overview about the properties is very usefull, but in my opinion it would be better in a seperat method/property (e.g. my_connection.prop).

[fwitte]

Maybe we implement different display modes? For backwards compatibility keep the old one (as default) and you can specify the extent yourself:

import numpy as np

import tespy
from tespy.components import Sink
from tespy.components import Source
from tespy.components import Valve
from tespy.connections import Connection
from tespy.connections import Ref
from tespy.networks import Network


nw = Network(iterinfo=False)
nw.units.set_defaults(
    pressure="bar", pressure_difference="bar", temperature="degC",
    enthalpy="kJ/kg"
)

so = Source("source")
va = Valve("expansion valve")
si = Sink("sink")

c1 = Connection(so, "out1", va, "in1", label="1")
c2 = Connection(va, "out1", si, "in1", label="2")
nw.add_conns(c1, c2)

c1.set_attr(fluid={"NH3": 1}, m=3.6, T=95.3, p=16)
c2.set_attr(p=Ref(c1, 0.5, 0))

nw.solve("design")

print("=" * 60)
print("display mode 'none' (default)")
print("=" * 60)
print(repr(c1))
print(repr(c1.T))
print(repr(va))
print(c1)

tespy.set_display_mode("compact")
print()
print("=" * 60)
print("display mode compact")
print("=" * 60)
print(repr(c1))
print(repr(c1.T))
print(repr(c1.fluid))
print(repr(va))
print(repr(va.pr))

tespy.set_display_mode("extensive")
print()
print("=" * 60)
print("display mode 'extensive'")
print("=" * 60)
print(c1)
print()
print(c2)
print()
print(va)
print()
print("print(c1.T):")
print(c1.T)
print()
print("print(c1.fluid):")
print(c1.fluid)

print()
print("=" * 60)
print("four component mixture (extensive)")
print("=" * 60)
air_so = Source("air source")
air_si = Sink("air sink")
c3 = Connection(air_so, "out1", air_si, "in1", label="air")
c3.set_attr(
    m=1.2,
    fluid={"N2": 0.7551, "O2": 0.2314, "Ar": 0.0129, "CO2": 0.0006}
)
print(c3)
print()
print("print(c3.fluid):")
print(c3.fluid)

print()
print("=" * 60)
print("other data containers (compact)")
print("=" * 60)
tespy.set_display_mode("compact")
print(repr(va.dp_char))
print(repr(va.Kv_char_group))
print(repr(va.Kv_analytical))
print(repr(c2.p_ref))

from tespy.tools.data_containers import ComponentArrayProperties

arr = ComponentArrayProperties(quantity="temperature")
arr.val_SI = np.array([300.0, 310.0, 320.0])
arr.val = np.array([26.85, 36.85, 46.85])
print(repr(arr))
print()
print("array property (extensive):")
tespy.set_display_mode("extensive")
print(arr)

print()
print("array property with many entries (extensive, numpy threshold=6):")
arr2 = ComponentArrayProperties(quantity="temperature")
arr2.val_SI = np.linspace(300, 500, 40)
arr2.val = arr2.val_SI - 273.15
np.set_printoptions(threshold=6)
print(arr2)
np.set_printoptions(threshold=1000)

============================================================
display mode 'none' (default)
============================================================
<tespy.connections.connection.Connection object at 0x726b6d9a4c20>
<tespy.tools.data_containers.FluidProperties object at 0x726b6d9ae990>
<tespy.components.piping.valve.Valve object at 0x726b6d9a4440>
<tespy.connections.connection.Connection object at 0x726b6d9a4c20>

============================================================
display mode compact
============================================================
Connection('1', source:out1 -> expansion valve:in1)
FluidProperties(val=95.3, unit='°C', val_SI=368.45, is_set=True)
FluidComposition(val={'NH3': 1.0}, is_set=['NH3'])
Valve('expansion valve')
ComponentProperties(val=0.5, unit='', val_SI=0.5, is_set=False, is_var=False)

============================================================
display mode 'extensive'
============================================================
Connection: 1 (source:out1 -> expansion valve:in1)

property        value  unit           SI value  spec
----------  ---------  ----------  -----------  ----
m              3.6000  kg / s       3.6000e+00  set
p             16.0000  bar          1.6000e+06  set
h           1797.2835  kJ / kg      1.7973e+06
T             95.3000  °C           3.6845e+02  set
T_bubble      41.0430  °C           3.1419e+02
T_dew         41.0430  °C           3.1419e+02
v              0.3730  m3 / s       3.7301e-01
x              1.0000               1.0000e+00
td_dew        54.2570  Δ°C          5.4257e+01
td_bubble    -54.2570  Δ°C         -5.4257e+01
vol            0.1036  m3 / kg      1.0361e-01
s           6103.0951  J / K / kg   6.1031e+03
fluid[NH3]     1.0000                           set

Connection: 2 (expansion valve:out1 -> sink:in1)

property               value  unit           SI value  spec
----------  ----------------  ----------  -----------  ----
m                     3.6000  kg / s       3.6000e+00
p                     8.0000  bar          8.0000e+05
h                  1797.2835  kJ / kg      1.7973e+06
T                    84.1502  °C           3.5730e+02
T_bubble             17.8634  °C           2.9101e+02
T_dew                17.8634  °C           2.9101e+02
v                     0.7514  m3 / s       7.5142e-01
x                     1.0000               1.0000e+00
td_dew               66.2868  Δ°C          6.6287e+01
td_bubble           -66.2868  Δ°C         -6.6287e+01
p_ref       0.5 * p('1') + 0                           set
vol                   0.2087  m3 / kg      2.0873e-01
s                  6421.5284  J / K / kg   6.4215e+03
fluid[NH3]            1.0000

Valve: expansion valve

parameter       value  unit    SI value  spec
---------  ----------  ----  ----------  ----
pr             0.5000        5.0000e-01
dp             8.0000  bar   8.0000e+05
zeta_d4    4.8763e+05        4.8763e+05
zeta       4.8763e+05        4.8763e+05

print(c1.T):
  value  unit    SI value  spec
-------  ----  ----------  ----
95.3000  °C    3.6845e+02  set

print(c1.fluid):
fluid  mass fraction  spec
-----  -------------  ----
NH3           1.0000  set

============================================================
four component mixture (extensive)
============================================================
Connection: air (air source:out1 -> air sink:in1)

property     value  unit  SI value  spec
----------  ------  ----  --------  ----
m           1.2000             nan  set
fluid[N2]   0.7551                  set
fluid[O2]   0.2314                  set
fluid[Ar]   0.0129                  set
fluid[CO2]  0.0006                  set

print(c3.fluid):
fluid  mass fraction  spec
-----  -------------  ----
N2            0.7551  set
O2            0.2314  set
Ar            0.0129  set
CO2           0.0006  set

============================================================
other data containers (compact)
============================================================
ComponentCharacteristics(param='m', char_func=CharLine, is_set=False)
GroupedComponentProperties(elements=['Kv_char', 'opening'], is_set=False)
SimpleDataContainer(val=nan, is_set=False)
ReferencedFluidProperties(ref=Ref('1', factor=0.5, delta=0), is_set=True)
ComponentArrayProperties(val=[26.85 36.85 46.85], quantity='temperature')

array property (extensive):
index    value  SI value
-----  -------  --------
0      26.8500  300.0000
1      36.8500  310.0000
2      46.8500  320.0000

array property with many entries (extensive, numpy threshold=6):
index     value  SI value
-----  --------  --------
0       26.8500  300.0000
1       31.9782  305.1282
2       37.1064  310.2564
...         ...       ...
37     216.5936  489.7436
38     221.7218  494.8718
39     226.8500  500.0000
(40 values, adjust numpy.set_printoptions or access val/val_SI directly to see all)

[HaSchneider]

Thats a great solution! Maybe together with something like a config/setting file to store the preferred settings permanent? I am not sure if something like that already exist in tespy, but that might also be interesting for defining default units or similar settings.

Keeping the current display mode for background compatibility seems to be best practice, but is it really necessary? It shouldnt change the behavior of type checks like the following, because it still returns the object in the code:
isinstance(my_conn('c1').T, FluidProperties)

[fwitte]

Thats a great solution! Maybe together with something like a config/setting file to store the preferred settings permanent? I am not sure if something like that already exist in tespy, but that might also be interesting for defining default units or similar settings.

good idea, I am putting that on a todo list however. For now, I will just implement the display options.

[fwitte]

Keeping the current display mode for background compatibility seems to be best practice, but is it really necessary? It shouldnt change the behavior of type checks like the following, because it still returns the object in the code:
isinstance(my_conn('c1').T, FluidProperties)

Implemented it now with default = compact, there is a going to be a mini example on the building blocks docs page on how to use it. I am making a release 0.11.1 right now, which will include the feature.