[Python] How to retrieve one data value from the result of a pandas DataFrame.groupby().mean()

Using Pandas 2.3.2 on Python 3.9.2 via JupyterLab.

I've collected a bunch of thermal data from a thing. I've already collated that data into DataFrame chunks that look like this:

zone data Setpoint
9 zone1 40.34347 40
13 zone1 40.07553 40
17 zone1 39.98359 40
21 zone1 40.06895 40
25 zone1 40.04465 40
.. ... ... ...
952 zone4 109.91890 110
956 zone4 109.90520 110
960 zone4 110.00600 110
964 zone4 110.02160 110
968 zone4 109.94940 110


Then I've used groupby and mean() to, well, group and create means:

means = temps[['zone','Setpoint','data']].groupby(['zone','Setpoint']).mean()

data
zone Setpoint
zone1 40 40.050959
50 50.030125
60 60.066517
70 70.050257
80 80.045247
90 90.071484
100 100.032826
110 110.137990
zone3 40 39.990645
50 50.015407
60 60.053120
70 70.044470
80 80.043304
90 90.077433
100 100.070493
110 110.140510
zone4 40 40.048473
50 50.017906
60 60.037044
70 70.012458
80 80.034280
90 90.087850
100 100.047793
110 110.067390


(Aside: I notice how "data" is a line above "zone" and "Setpoint", and I don't know what that's trying to tell me about the structure)

I can grab one zone's worth of info by doing z1means = means.loc['zone1']:

data
Setpoint
40 40.050959
50 50.030125
60 60.066517
70 70.050257
80 80.045247
90 90.071484
100 100.032826
110 110.137990


What I can't figure out is how to get at, e.g., the "data" value where "Setpoint" is 80:

*some undiscovered syntax*

80.045247

I've come to understand that the "Setpoint" value is the index on the DataFrame object held in z1means but can't figure out how to refer to the data using it:

<class 'pandas.core.frame.DataFrame'>
Index: 8 entries, 40 to 110
Data columns (total 1 columns):
# Column Non-Null Count Dtype
--- ------ -------------- -----
0 data 8 non-null float64
dtypes: float64(1)
memory usage: 128.0 bytes
None


I can only imagine that the Index: 8 entries, 40 to 110 is telling me something important, but I can't figure out what that is or how to use it.

Things I've tried and their results:

z1means[80] -> KeyError: 80
z1means.at(80) -> TypeError: '_AtIndexer' object is not callable
z1means.loc(80) -> KeyError: 80, ValueError: No axis named 80 for object type DataFrame
z1means.iloc(80) -> Same as .loc
z1means.loc(z1means['Setpoint'] == 80) -> KeyError: Setpoint


What am I just not grasping here?

Continue reading...