Created
June 18, 2020 14:15
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training a dumb classifier
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# Importing the dataset. | |
from sklearn.datasets import fetch_openml | |
mnist = fetch_openml('mnist_784', version=1) | |
# Creating independent and dependent variables. | |
X, y = mnist['data'], mnist['target'] | |
# Splitting the data into training set and test set. | |
X_train, X_test, y_train, y_test = X[:60000], X[60000:], y[:60000], y[60000:] | |
""" | |
The training set is already shuffled for us, which is good as this guarantees that all | |
cross-validation folds will be similar. | |
""" | |
# Training a binary classifier. | |
y_train_5 = (y_train == 5) # True for all 5s, False for all other digits. | |
y_test_5 = (y_test == 5) | |
""" | |
Building a dumb classifier that just classifies every single image in the “not-5” class. | |
""" | |
from sklearn.model_selection import cross_val_score | |
from sklearn.base import BaseEstimator | |
class Never5Classifier(BaseEstimator): | |
def fit(self, X, y=None): | |
pass | |
def predict(self, X): | |
return np.zeros((len(X), 1), dtype=bool) | |
never_5_clf = Never5Classifier() | |
cross_val_score(never_5_clf, X_train, y_train_5, cv=3, scoring="accuracy") |
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