Unpacking a python list into a dataframe

Question

I'm fairly new to python and I'm facing an issue with the datatype returned by a function. I have two functions prepare and model

def Prepare(Inputdf):

    x0 = list(range(e ,s+1 ,-1))
    X = Inputdf[x0] 
    Y = Inputdf['y0']

    return [X,Y]

# Linear Model
def Model(Inputdf, X, Y):

    #Train
    X = sm.add_constant(X)
    lmodel = sm.OLS(Y, X).fit()
    summ = lmodel.summary()

    #Test
    x1 = list(range(e-1 ,s ,-1))
    A = Inputdf[x1]
    A = sm.add_constant(A)

    newcol = lmodel.predict(A)
    newdf = pd.concat([Inputdf, newcol], axis=1)

    return [newdf]

They are called in the loop below. The function returns a list but I'm not sure how to convert the output into a dataframe

forecast = []
for i in wh:
    TrainFinal = TrainInput[TrainInput['column'].isin([i])]
    TestFinal = TestInput[TestInput['column'].isin([i])]

    Modelresult = Model(TestFinal, *Prepare(TrainFinal))
    forecast.append(Modelresult)

    print (forecast)

the output looks like this

[[                   country    y1          0
6990  United Arab Emirates  42.0  24.314137
...                    ...   ...        ...
7426  United Arab Emirates  12.0   8.281969
[71 rows x 3 columns]], 
[                   country    y1          0
8338  United Arab Emirates  97.0  66.740899
...                    ...   ...        ...
8696  United Arab Emirates   8.0  12.884740
[67 rows x 3 columns]], 
[    country    y1          0
284   Chile   6.0  16.672239
...   ...     ...     ...
374   Chile   5.0  13.534690
[67 rows x 3 columns]]

it almost seems like your output is a list of dataframes

Vittorio Trettenero
– Vittorio Trettenero

2020-06-08 15:22:55 +00:00
Commented Jun 8, 2020 at 15:22 — Vittorio Trettenero
– Vittorio Trettenero, Commented Jun 8, 2020 at 15:22
Yes it is. figured out the problem :)

Simi Ayo-Vaughan
– Simi Ayo-Vaughan

2020-06-10 08:13:20 +00:00
Commented Jun 10, 2020 at 8:13 — Simi Ayo-Vaughan
– Simi Ayo-Vaughan, Commented Jun 10, 2020 at 8:13

Simi Ayo-Vaughan · Accepted Answer · 2020-06-10 08:18:55Z

1

I found out what I was doing wrong. I just removed the brackets in front of the returned dataframe in the 'Model Function'

return [newdf] -> return newdf

then I concatenated the results instead of appending them, and I reset the index to get my final output :)

forecast = pd.concat(Modelresult)
forecast.reset_index(drop=True, inplace=True)

answered Jun 10, 2020 at 8:18

Simi Ayo-Vaughan

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