Merge pull request lisa-lab#92 from memimo/predict

Predict function for logistic regression.

Author: nouiz

code/convolutional_mlp.py

@@ -110,6 +110,9 @@ def __init__(self, rng, input, filter_shape, image_shape, poolsize=(2, 2)):
         # store parameters of this layer
         self.params = [self.W, self.b]
 
+        # keep track of model input
+        self.input = input
+
 
 def evaluate_lenet5(learning_rate=0.1, n_epochs=200,
                     dataset='mnist.pkl.gz',

code/logistic_cg.py

@@ -97,6 +97,9 @@ def __init__(self, input, n_in, n_out):
         # symbolic form
         self.y_pred = T.argmax(self.p_y_given_x, axis=1)
 
+        # keep track of model input
+        self.input = input
+
     def negative_log_likelihood(self, y):
         """Return the negative log-likelihood of the prediction of this model
         under a given target distribution.

code/logistic_sgd.py

@@ -109,6 +109,9 @@ def __init__(self, input, n_in, n_out):
         # parameters of the model
         self.params = [self.W, self.b]
 
+        # keep track of model input
+        self.input = input
+
     def negative_log_likelihood(self, y):
         """Return the mean of the negative log-likelihood of the prediction
         of this model under a given target distribution.
@@ -415,6 +418,10 @@ def sgd_optimization_mnist(learning_rate=0.13, n_epochs=1000,
                         )
                     )
 
+                    # save the best model
+                    with open('best_model.pkl', 'w') as f:
+                        cPickle.dump(classifier, f)
+
             if patience <= iter:
                 done_looping = True
                 break
@@ -433,5 +440,31 @@ def sgd_optimization_mnist(learning_rate=0.13, n_epochs=1000,
                           os.path.split(__file__)[1] +
                           ' ran for %.1fs' % ((end_time - start_time)))
 
+
+def predict():
+    """
+    An example of how to load a trained model and use it
+    to predict labels.
+    """
+
+    # load the saved model
+    classifier = cPickle.load(open('best_model.pkl'))
+
+    # compile a predictor function
+    predict_model = theano.function(
+        inputs=[classifier.input],
+        outputs=classifier.y_pred)
+
+    # We can test it on some examples from test test
+    dataset='mnist.pkl.gz'
+    datasets = load_data(dataset)
+    test_set_x, test_set_y = datasets[2]
+    test_set_x = test_set_x.get_value()
+
+    predicted_values = predict_model(test_set_x[:10])
+    print ("Predicted values for the first 10 examples in test set:")
+    print predicted_values
+
+
 if __name__ == '__main__':
     sgd_optimization_mnist()

code/mlp.py

@@ -191,6 +191,9 @@ def __init__(self, rng, input, n_in, n_hidden, n_out):
         self.params = self.hiddenLayer.params + self.logRegressionLayer.params
         # end-snippet-3
 
+        # keep track of model input
+        self.input = input
+
 
 def test_mlp(learning_rate=0.01, L1_reg=0.00, L2_reg=0.0001, n_epochs=1000,
              dataset='mnist.pkl.gz', batch_size=20, n_hidden=500):

doc/logreg.txt

@@ -264,6 +264,19 @@ approximately 1.936 epochs/sec and it took 75 epochs to reach a test
 error of 7.489%. On the GPU the code does almost 10.0 epochs/sec. For this
 instance we used a batch size of 600.
 
+
+Prediction Using a Trained Model
++++++++++++++++++++++++++++++++
+
+``sgd_optimization_mnist`` serialize and pickle the model each time new
+lowest validation error is reached. We can reload this model and predict
+labels of new data. ``predict`` function shows an example of how
+this could be done.
+
+.. literalinclude:: ../code/logistic_sgd.py
+    :pyobject: predict
+
+
 .. rubric:: Footnotes
 
 .. [#f1] For smaller datasets and simpler models, more sophisticated descent