expecting a 2D array error in python

Question

I am trying the further below linear regression python code but I am getting the error: "expecting a 2D array got 1D array instead: Array=[16]". What could be wrong?

 from sklearn.linear_model import LinearRegression
 # Training data
 X = [[6], [8], [10], [14], [18]]
 y = [[7], [9], [13], [17.5], [19]]
 # Create and fit the model
 model = LinearRegression()
 model.fit(X, y)
 print 'A 16" pitta bread should cost: $%.2f' % model.predict([16])[0]

==================================================================== Traceback (most recent call last):

 File "<ipython-input-27-8b7f351334d7>", line 1, in <module>
 runfile('C:/ML/train.py', wdir='C:/ML')

 File "C:\Users\admin\Anaconda3\lib\site- 
 packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
 execfile(filename, namespace)

 File "C:\Users\admin\Anaconda3\lib\site- 
 packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)

 File "C:/ML/train.py", line 16, in <module>
 model.predict([12])[0]

 File "C:\Users\admin\Anaconda3\lib\site- 
 packages\sklearn\linear_model\base.py", line 256, in predict
return self._decision_function(X)

   File "C:\Users\admin\Anaconda3\lib\site- 
   packages\sklearn\linear_model\base.py", line 239, in _decision_function
   X = check_array(X, accept_sparse=['csr', 'csc', 'coo'])

File "C:\Users\admin\Anaconda3\lib\site- 
 packages\sklearn\utils\validation.py", line 441, in check_array
"if it contains a single sample.".format(array))

ValueError: Expected 2D array, got 1D array instead:
 array=[16].
Reshape your data either using array.reshape(-1, 1) if your data has a single 
feature or array.reshape(1, -1) if it contains a single sample.

@IPPOKRATISKARAKOTSOGLOU, if my answer helped you please upvote it as well as accepting it. many thanks — aydow
– aydow, Commented Aug 5, 2018 at 8:43

aydow · Accepted Answer · 2018-08-04 12:38:15Z

1

You're only providing a 1D array. Try

>>> print 'A 16" pitta bread should cost: $%.2f' % model.predict([16][0])
>>> A 16" pitta bread should cost: $18.14

answered Aug 4, 2018 at 12:38

aydow

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