Destroxia - 5 months ago 83

Python Question

I've been attempting to fit this data by a Linear Regression, following a tutorial on bigdataexaminer. Everything was working fine up until this point. I imported LinearRegression from sklearn, and printed the number of coefficients just fine. This was the code before I attempted to grab the coefficients from the console.

`import numpy as np`

import pandas as pd

import scipy.stats as stats

import matplotlib.pyplot as plt

import sklearn

from sklearn.datasets import load_boston

from sklearn.linear_model import LinearRegression

boston = load_boston()

bos = pd.DataFrame(boston.data)

bos.columns = boston.feature_names

bos['PRICE'] = boston.target

X = bos.drop('PRICE', axis = 1)

lm = LinearRegression()

After I had all this set up I ran the following command, and it returned the proper output:

`In [68]: print('Number of coefficients:', len(lm.coef_)`

Number of coefficients: 13

However, now if I ever try to print this same line again, or use 'lm.coef_', it tells me coef_ isn't an attribute of LinearRegression, right after I JUST used it successfully, and I didn't touch any of the code before I tried it again.

`In [70]: print('Number of coefficients:', len(lm.coef_))`

Traceback (most recent call last):

File "<ipython-input-70-5ad192630df3>", line 1, in <module>

print('Number of coefficients:', len(lm.coef_))

AttributeError: 'LinearRegression' object has no attribute 'coef_'

Answer

The `coef_`

attribute is created when the `fit()`

method is called. Before that, it will be undefined:

```
>>> import numpy as np
>>> import pandas as pd
>>> from sklearn.datasets import load_boston
>>> from sklearn.linear_model import LinearRegression
>>> boston = load_boston()
>>> lm = LinearRegression()
>>> lm.coef_
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-22-975676802622> in <module>()
7
8 lm = LinearRegression()
----> 9 lm.coef_
AttributeError: 'LinearRegression' object has no attribute 'coef_'
```

If we call `fit()`

, the coefficients will be defined:

```
>>> lm.fit(boston.data, boston.target)
>>> lm.coef_
array([ -1.07170557e-01, 4.63952195e-02, 2.08602395e-02,
2.68856140e+00, -1.77957587e+01, 3.80475246e+00,
7.51061703e-04, -1.47575880e+00, 3.05655038e-01,
-1.23293463e-02, -9.53463555e-01, 9.39251272e-03,
-5.25466633e-01])
```

My guess is that somehow you forgot to call `fit()`

when you ran the problematic line.