TypeError: '

Question

I am making a feature selection by using chi square method on Python, however I am having some trouble with the last block of code, I am using a dataset composed just by categorical variables, the original dataset is composed by variables names (columns) and 'yes' and 'no'(rows) for each observation.

Here is the error:

TypeError                                 Traceback (most recent call last)
 in 
     1 fs = SelectKBest(score_func=chi2, k='all')
----> 2 fs.fit(X_train, y_train)
     3 X_train_fs = fs.transform(X_train)
     4 X_test_fs = fs.transform(X_test)

~\Documents\Nueva carpeta\lib\site-packages\sklearn\feature_selection\univariate_selection.py in fit(self, X, y)
   347 
   348         self._check_params(X, y)
--> 349         score_func_ret = self.score_func(X, y)
   350         if isinstance(score_func_ret, (list, tuple)):
   351             self.scores_, self.pvalues_ = score_func_ret

~\Documents\Nueva carpeta\lib\site-packages\sklearn\feature_selection\univariate_selection.py in chi2(X, y)
   213     # numerical stability.
   214     X = check_array(X, accept_sparse='csr')
--> 215     if np.any((X.data if issparse(X) else X) < 0):
   216         raise ValueError("Input X must be non-negative.")
   217 

TypeError: '<' not supported between instances of 'numpy.ndarray' and 'int'

And here is the code that I am currently using:

# example of chi squared feature selection for categorical data
from pandas import read_csv
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import LabelEncoder
from sklearn.preprocessing import OrdinalEncoder
from sklearn.feature_selection import SelectKBest
from sklearn.feature_selection import chi2
from matplotlib import pyplot

# load the dataset
def load_dataset(filename):
    # load the dataset as a pandas DataFrame
    data = read_csv(filename, header=None)
    # retrieve numpy array
    dataset = data.values
    # split into input (X) and output (y) variables
    X = dataset[:, :-1]
    y = dataset[:,-1]
    # format all fields as string
    X = X.astype(str)
    return X, y

# prepare input data
def prepare_inputs(X_train, X_test):
    oe = OrdinalEncoder()
    oe.fit(X_train)
    X_train_enc = oe.transform(X_train)
    X_test_enc = oe.transform(X_test)
    return X_train_enc, X_test_enc

# prepare target
def prepare_targets(y_train, y_test):
    le = LabelEncoder()
    le.fit(y_train)
    y_train_enc = le.transform(y_train)
    y_test_enc = le.transform(y_test)
    return y_train_enc, y_test_enc

# feature selection 
def select_features(X_train, y_train, X_test):
    fs = SelectKBest(score_func=chi2, k='all')
    fs.fit(X_train, y_train)
    X_train_fs = fs.transform(X_train)
    X_test_fs = fs.transform(X_test)
    return X_train_fs, X_test_fs, fs     #This is the block where the problem arises.

Thanks in advance

TypeError: '<' not supported between instances of 'numpy.ndarray' and 'int'

0 Answers