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To klasyfikuje notebooków filmowe opinii jako pozytywne lub negatywne wykorzystujące tekst przeglądu. To jest przykład binarnego -lub dwie klasy klasyfikacji, ważnym i powszechnie stosowanego rodzaju problemu uczenia maszynowego.
Użyjemy zestawu danych IMDB zawierający tekst 50.000 recenzje filmów z Bazy Internet Movie . Są one podzielone na 25 000 recenzji do szkolenia i 25 000 recenzji do testów. Zestawy treningowe i testowe są zrównoważone, co oznacza, że zawierają taką samą liczbę pozytywnych i negatywnych opinii.
Ten notebook korzysta tf.keras , API wysokiego poziomu zbudować i modeli kolejowych w TensorFlow i TensorFlow Hub , biblioteka i platforma do nauki transferowego. Dla bardziej zaawansowanych tekstu klasyfikacja samouczka użyciu tf.keras , zobacz mlcC Tekst Klasyfikacja Guide .
Więcej modeli
Tutaj można znaleźć bardziej wyrazisty lub wydajnych modeli, które można użyć do wygenerowania osadzanie tekstu.
Ustawiać
import numpy as np
import tensorflow as tf
import tensorflow_hub as hub
import tensorflow_datasets as tfds
import matplotlib.pyplot as plt
print("Version: ", tf.__version__)
print("Eager mode: ", tf.executing_eagerly())
print("Hub version: ", hub.__version__)
print("GPU is", "available" if tf.config.list_physical_devices('GPU') else "NOT AVAILABLE")
Version: 2.7.0 Eager mode: True Hub version: 0.12.0 GPU is available
Pobierz zbiór danych IMDB
IMDb zestaw danych jest dostępna na zbiorach danych TensorFlow . Poniższy kod pobiera zestaw danych IMDB na komputer (lub środowisko wykonawcze colab):
train_data, test_data = tfds.load(name="imdb_reviews", split=["train", "test"],
batch_size=-1, as_supervised=True)
train_examples, train_labels = tfds.as_numpy(train_data)
test_examples, test_labels = tfds.as_numpy(test_data)
WARNING:tensorflow:From /tmpfs/src/tf_docs_env/lib/python3.7/site-packages/tensorflow_datasets/core/dataset_builder.py:622: get_single_element (from tensorflow.python.data.experimental.ops.get_single_element) is deprecated and will be removed in a future version. Instructions for updating: Use `tf.data.Dataset.get_single_element()`. WARNING:tensorflow:From /tmpfs/src/tf_docs_env/lib/python3.7/site-packages/tensorflow_datasets/core/dataset_builder.py:622: get_single_element (from tensorflow.python.data.experimental.ops.get_single_element) is deprecated and will be removed in a future version. Instructions for updating: Use `tf.data.Dataset.get_single_element()`.
Przeglądaj dane
Poświęćmy chwilę, aby zrozumieć format danych. Każdy przykład to zdanie reprezentujące recenzję filmu i odpowiadającą mu etykietę. Zdanie nie jest w żaden sposób preprocesowane. Etykieta jest liczbą całkowitą 0 lub 1, gdzie 0 oznacza negatywną recenzję, a 1 pozytywną recenzję.
print("Training entries: {}, test entries: {}".format(len(train_examples), len(test_examples)))
Training entries: 25000, test entries: 25000
Wydrukujmy pierwsze 10 przykładów.
train_examples[:10]
array([b"This was an absolutely terrible movie. Don't be lured in by Christopher Walken or Michael Ironside. Both are great actors, but this must simply be their worst role in history. Even their great acting could not redeem this movie's ridiculous storyline. This movie is an early nineties US propaganda piece. The most pathetic scenes were those when the Columbian rebels were making their cases for revolutions. Maria Conchita Alonso appeared phony, and her pseudo-love affair with Walken was nothing but a pathetic emotional plug in a movie that was devoid of any real meaning. I am disappointed that there are movies like this, ruining actor's like Christopher Walken's good name. I could barely sit through it.",
b'I have been known to fall asleep during films, but this is usually due to a combination of things including, really tired, being warm and comfortable on the sette and having just eaten a lot. However on this occasion I fell asleep because the film was rubbish. The plot development was constant. Constantly slow and boring. Things seemed to happen, but with no explanation of what was causing them or why. I admit, I may have missed part of the film, but i watched the majority of it and everything just seemed to happen of its own accord without any real concern for anything else. I cant recommend this film at all.',
b'Mann photographs the Alberta Rocky Mountains in a superb fashion, and Jimmy Stewart and Walter Brennan give enjoyable performances as they always seem to do. <br /><br />But come on Hollywood - a Mountie telling the people of Dawson City, Yukon to elect themselves a marshal (yes a marshal!) and to enforce the law themselves, then gunfighters battling it out on the streets for control of the town? <br /><br />Nothing even remotely resembling that happened on the Canadian side of the border during the Klondike gold rush. Mr. Mann and company appear to have mistaken Dawson City for Deadwood, the Canadian North for the American Wild West.<br /><br />Canadian viewers be prepared for a Reefer Madness type of enjoyable howl with this ludicrous plot, or, to shake your head in disgust.',
b'This is the kind of film for a snowy Sunday afternoon when the rest of the world can go ahead with its own business as you descend into a big arm-chair and mellow for a couple of hours. Wonderful performances from Cher and Nicolas Cage (as always) gently row the plot along. There are no rapids to cross, no dangerous waters, just a warm and witty paddle through New York life at its best. A family film in every sense and one that deserves the praise it received.',
b'As others have mentioned, all the women that go nude in this film are mostly absolutely gorgeous. The plot very ably shows the hypocrisy of the female libido. When men are around they want to be pursued, but when no "men" are around, they become the pursuers of a 14 year old boy. And the boy becomes a man really fast (we should all be so lucky at this age!). He then gets up the courage to pursue his true love.',
b"This is a film which should be seen by anybody interested in, effected by, or suffering from an eating disorder. It is an amazingly accurate and sensitive portrayal of bulimia in a teenage girl, its causes and its symptoms. The girl is played by one of the most brilliant young actresses working in cinema today, Alison Lohman, who was later so spectacular in 'Where the Truth Lies'. I would recommend that this film be shown in all schools, as you will never see a better on this subject. Alison Lohman is absolutely outstanding, and one marvels at her ability to convey the anguish of a girl suffering from this compulsive disorder. If barometers tell us the air pressure, Alison Lohman tells us the emotional pressure with the same degree of accuracy. Her emotional range is so precise, each scene could be measured microscopically for its gradations of trauma, on a scale of rising hysteria and desperation which reaches unbearable intensity. Mare Winningham is the perfect choice to play her mother, and does so with immense sympathy and a range of emotions just as finely tuned as Lohman's. Together, they make a pair of sensitive emotional oscillators vibrating in resonance with one another. This film is really an astonishing achievement, and director Katt Shea should be proud of it. The only reason for not seeing it is if you are not interested in people. But even if you like nature films best, this is after all animal behaviour at the sharp edge. Bulimia is an extreme version of how a tormented soul can destroy her own body in a frenzy of despair. And if we don't sympathise with people suffering from the depths of despair, then we are dead inside.",
b'Okay, you have:<br /><br />Penelope Keith as Miss Herringbone-Tweed, B.B.E. (Backbone of England.) She\'s killed off in the first scene - that\'s right, folks; this show has no backbone!<br /><br />Peter O\'Toole as Ol\' Colonel Cricket from The First War and now the emblazered Lord of the Manor.<br /><br />Joanna Lumley as the ensweatered Lady of the Manor, 20 years younger than the colonel and 20 years past her own prime but still glamourous (Brit spelling, not mine) enough to have a toy-boy on the side. It\'s alright, they have Col. Cricket\'s full knowledge and consent (they guy even comes \'round for Christmas!) Still, she\'s considerate of the colonel enough to have said toy-boy her own age (what a gal!)<br /><br />David McCallum as said toy-boy, equally as pointlessly glamourous as his squeeze. Pilcher couldn\'t come up with any cover for him within the story, so she gave him a hush-hush job at the Circus.<br /><br />and finally:<br /><br />Susan Hampshire as Miss Polonia Teacups, Venerable Headmistress of the Venerable Girls\' Boarding-School, serving tea in her office with a dash of deep, poignant advice for life in the outside world just before graduation. Her best bit of advice: "I\'ve only been to Nancherrow (the local Stately Home of England) once. I thought it was very beautiful but, somehow, not part of the real world." Well, we can\'t say they didn\'t warn us.<br /><br />Ah, Susan - time was, your character would have been running the whole show. They don\'t write \'em like that any more. Our loss, not yours.<br /><br />So - with a cast and setting like this, you have the re-makings of "Brideshead Revisited," right?<br /><br />Wrong! They took these 1-dimensional supporting roles because they paid so well. After all, acting is one of the oldest temp-jobs there is (YOU name another!)<br /><br />First warning sign: lots and lots of backlighting. They get around it by shooting outdoors - "hey, it\'s just the sunlight!"<br /><br />Second warning sign: Leading Lady cries a lot. When not crying, her eyes are moist. That\'s the law of romance novels: Leading Lady is "dewy-eyed."<br /><br />Henceforth, Leading Lady shall be known as L.L.<br /><br />Third warning sign: L.L. actually has stars in her eyes when she\'s in love. Still, I\'ll give Emily Mortimer an award just for having to act with that spotlight in her eyes (I wonder . did they use contacts?)<br /><br />And lastly, fourth warning sign: no on-screen female character is "Mrs." She\'s either "Miss" or "Lady."<br /><br />When all was said and done, I still couldn\'t tell you who was pursuing whom and why. I couldn\'t even tell you what was said and done.<br /><br />To sum up: they all live through World War II without anything happening to them at all.<br /><br />OK, at the end, L.L. finds she\'s lost her parents to the Japanese prison camps and baby sis comes home catatonic. Meanwhile (there\'s always a "meanwhile,") some young guy L.L. had a crush on (when, I don\'t know) comes home from some wartime tough spot and is found living on the street by Lady of the Manor (must be some street if SHE\'s going to find him there.) Both war casualties are whisked away to recover at Nancherrow (SOMEBODY has to be "whisked away" SOMEWHERE in these romance stories!)<br /><br />Great drama.',
b'The film is based on a genuine 1950s novel.<br /><br />Journalist Colin McInnes wrote a set of three "London novels": "Absolute Beginners", "City of Spades" and "Mr Love and Justice". I have read all three. The first two are excellent. The last, perhaps an experiment that did not come off. But McInnes\'s work is highly acclaimed; and rightly so. This musical is the novelist\'s ultimate nightmare - to see the fruits of one\'s mind being turned into a glitzy, badly-acted, soporific one-dimensional apology of a film that says it captures the spirit of 1950s London, and does nothing of the sort.<br /><br />Thank goodness Colin McInnes wasn\'t alive to witness it.',
b'I really love the sexy action and sci-fi films of the sixties and its because of the actress\'s that appeared in them. They found the sexiest women to be in these films and it didn\'t matter if they could act (Remember "Candy"?). The reason I was disappointed by this film was because it wasn\'t nostalgic enough. The story here has a European sci-fi film called "Dragonfly" being made and the director is fired. So the producers decide to let a young aspiring filmmaker (Jeremy Davies) to complete the picture. They\'re is one real beautiful woman in the film who plays Dragonfly but she\'s barely in it. Film is written and directed by Roman Coppola who uses some of his fathers exploits from his early days and puts it into the script. I wish the film could have been an homage to those early films. They could have lots of cameos by actors who appeared in them. There is one actor in this film who was popular from the sixties and its John Phillip Law (Barbarella). Gerard Depardieu, Giancarlo Giannini and Dean Stockwell appear as well. I guess I\'m going to have to continue waiting for a director to make a good homage to the films of the sixties. If any are reading this, "Make it as sexy as you can"! I\'ll be waiting!',
b'Sure, this one isn\'t really a blockbuster, nor does it target such a position. "Dieter" is the first name of a quite popular German musician, who is either loved or hated for his kind of acting and thats exactly what this movie is about. It is based on the autobiography "Dieter Bohlen" wrote a few years ago but isn\'t meant to be accurate on that. The movie is filled with some sexual offensive content (at least for American standard) which is either amusing (not for the other "actors" of course) or dumb - it depends on your individual kind of humor or on you being a "Bohlen"-Fan or not. Technically speaking there isn\'t much to criticize. Speaking of me I find this movie to be an OK-movie.'],
dtype=object)
Wydrukujmy też pierwsze 10 etykiet.
train_labels[:10]
array([0, 0, 0, 1, 1, 1, 0, 0, 0, 0])
Zbuduj model
Sieć neuronowa jest tworzona przez układanie warstw — wymaga to trzech głównych decyzji architektonicznych:
- Jak reprezentować tekst?
- Ile warstw użyć w modelu?
- Ile ukryte jednostki użyć dla każdej warstwy?
W tym przykładzie dane wejściowe składają się ze zdań. Etykiety do przewidzenia to 0 lub 1.
Jednym ze sposobów reprezentacji tekstu jest konwersja zdań na wektory osadzenia. Jako pierwszą warstwę możemy użyć wstępnie wytrenowanego osadzania tekstu, co będzie miało dwie zalety:
- nie musimy się martwić o wstępne przetwarzanie tekstu,
- możemy skorzystać z transferu uczenia się.
W tym przykładzie użyjemy model z TensorFlow Hub o nazwie google / nnlm-en-dim50 / 2 .
Istnieją dwa inne modele do przetestowania na potrzeby tego samouczka:
- google / nnlm-en-dim50-z-normalizacji / 2 - takie same jak google / nnlm-en-dim50 / 2 , ale z dodatkowym normalizacja tekstu, aby usunąć znaki interpunkcyjne. Może to pomóc w uzyskaniu lepszego pokrycia osadzania w słowniku dla tokenów w tekście wejściowym.
- pomocną / nnlm-en-dim128-z normalizacją / 2 - większy model z osadzonymi wymiaru 128 zamiast mniejsza 50.
Najpierw utwórzmy warstwę Keras, która wykorzystuje model TensorFlow Hub do osadzania zdań i wypróbujmy ją na kilku przykładach wejściowych. Zauważmy, że kształt wyjściowy wytwarzanych zanurzeń jest spodziewane: (num_examples, embedding_dimension) .
model = "https://tfhub.dev/google/nnlm-en-dim50/2"
hub_layer = hub.KerasLayer(model, input_shape=[], dtype=tf.string, trainable=True)
hub_layer(train_examples[:3])
<tf.Tensor: shape=(3, 50), dtype=float32, numpy=
array([[ 0.5423194 , -0.01190171, 0.06337537, 0.0686297 , -0.16776839,
-0.10581177, 0.168653 , -0.04998823, -0.31148052, 0.07910344,
0.15442258, 0.01488661, 0.03930155, 0.19772716, -0.12215477,
-0.04120982, -0.27041087, -0.21922147, 0.26517656, -0.80739075,
0.25833526, -0.31004202, 0.2868321 , 0.19433866, -0.29036498,
0.0386285 , -0.78444123, -0.04793238, 0.41102988, -0.36388886,
-0.58034706, 0.30269453, 0.36308962, -0.15227163, -0.4439151 ,
0.19462997, 0.19528405, 0.05666233, 0.2890704 , -0.28468323,
-0.00531206, 0.0571938 , -0.3201319 , -0.04418665, -0.08550781,
-0.55847436, -0.2333639 , -0.20782956, -0.03543065, -0.17533456],
[ 0.56338924, -0.12339553, -0.10862677, 0.7753425 , -0.07667087,
-0.15752274, 0.01872334, -0.08169781, -0.3521876 , 0.46373403,
-0.08492758, 0.07166861, -0.00670818, 0.12686071, -0.19326551,
-0.5262643 , -0.32958236, 0.14394784, 0.09043556, -0.54175544,
0.02468163, -0.15456744, 0.68333143, 0.09068333, -0.45327246,
0.23180094, -0.8615696 , 0.3448039 , 0.12838459, -0.58759046,
-0.40712303, 0.23061076, 0.48426905, -0.2712814 , -0.5380918 ,
0.47016335, 0.2257274 , -0.00830665, 0.28462422, -0.30498496,
0.04400366, 0.25025868, 0.14867125, 0.4071703 , -0.15422425,
-0.06878027, -0.40825695, -0.31492147, 0.09283663, -0.20183429],
[ 0.7456156 , 0.21256858, 0.1440033 , 0.52338624, 0.11032254,
0.00902788, -0.36678016, -0.08938274, -0.24165548, 0.33384597,
-0.111946 , -0.01460045, -0.00716449, 0.19562715, 0.00685217,
-0.24886714, -0.42796353, 0.1862 , -0.05241097, -0.664625 ,
0.13449019, -0.22205493, 0.08633009, 0.43685383, 0.2972681 ,
0.36140728, -0.71968895, 0.05291242, -0.1431612 , -0.15733941,
-0.15056324, -0.05988007, -0.08178931, -0.15569413, -0.09303784,
-0.18971168, 0.0762079 , -0.02541647, -0.27134502, -0.3392682 ,
-0.10296471, -0.27275252, -0.34078008, 0.20083308, -0.26644838,
0.00655449, -0.05141485, -0.04261916, -0.4541363 , 0.20023566]],
dtype=float32)>
Zbudujmy teraz pełny model:
model = tf.keras.Sequential()
model.add(hub_layer)
model.add(tf.keras.layers.Dense(16, activation='relu'))
model.add(tf.keras.layers.Dense(1))
model.summary()
Model: "sequential"
_________________________________________________________________
Layer (type) Output Shape Param #
=================================================================
keras_layer (KerasLayer) (None, 50) 48190600
dense (Dense) (None, 16) 816
dense_1 (Dense) (None, 1) 17
=================================================================
Total params: 48,191,433
Trainable params: 48,191,433
Non-trainable params: 0
_________________________________________________________________
Warstwy są układane w stos sekwencyjny, aby zbudować klasyfikator:
- Pierwsza warstwa to warstwa TensorFlow Hub. Ta warstwa używa wstępnie wytrenowanego zapisanego modelu do mapowania zdania na jego wektor osadzania. Model, który używamy ( google / nnlm-en-dim50 / 2 ) dzieli zdanie na tokeny, osadza każdy żeton, a następnie łączy osadzanie. Uzyskane wymiary są następujące:
(num_examples, embedding_dimension). - Ten czas trwania wektora wyjściowego jest przetłaczany przez całkowicie połączonej (
Dense) warstwy 16 jednostek ukrytych. - Ostatnia warstwa jest gęsto połączona z pojedynczym węzłem wyjściowym. To wyprowadza logity: logarytmiczne szanse prawdziwej klasy, zgodnie z modelem.
Ukryte jednostki
Powyższy model ma dwie warstwy pośrednie lub „ukryte”, pomiędzy wejściem i wyjściem. Liczba wyjść (jednostek, węzłów lub neuronów) jest wymiarem przestrzeni reprezentacyjnej warstwy. Innymi słowy, ilość swobody, jaką sieć ma dozwolona podczas uczenia się wewnętrznej reprezentacji.
Jeśli model ma więcej ukrytych jednostek (przestrzeń reprezentacji o wyższym wymiarze) i/lub więcej warstw, sieć może nauczyć się bardziej złożonych reprezentacji. Powoduje to jednak, że sieć jest bardziej kosztowna obliczeniowo i może prowadzić do uczenia się niepożądanych wzorców — wzorców, które poprawiają wydajność na danych uczących, ale nie na danych testowych. To się nazywa nadmiernego dopasowywania, a my go zbadać później.
Funkcja strat i optymalizator
Model potrzebuje funkcji straty i optymalizatora do uczenia. Ponieważ jest binarny problemu klasyfikacji, a model wyjścia prawdopodobieństwem (warstwy pojedynczej jednostki z sigmoidalnej aktywacji) użyjemy binary_crossentropy funkcję strat.
To nie jest jedynym wyborem dla funkcji strat, można na przykład wybrać mean_squared_error . Ale ogólnie, binary_crossentropy jest lepsze dla czynienia z prawdopodobieństw-mierzy „odległość” między rozkładów prawdopodobieństwa, lub w naszym przypadku, między podziałem gruntu prawdy i prognoz.
Później, gdy będziemy badać problemy z regresją (powiedzmy, aby przewidzieć cenę domu), zobaczymy, jak użyć innej funkcji straty zwanej błędem średniokwadratowym.
Teraz skonfiguruj model tak, aby używał optymalizatora i funkcji straty:
model.compile(optimizer='adam',
loss=tf.losses.BinaryCrossentropy(from_logits=True),
metrics=[tf.metrics.BinaryAccuracy(threshold=0.0, name='accuracy')])
Utwórz zestaw walidacyjny
Podczas uczenia chcemy sprawdzić dokładność modelu na danych, których wcześniej nie widział. Utwórz zestaw walidacji poprzez ustawienie oprócz 10.000 przykładów z oryginalnych danych szkolenia. (Dlaczego nie skorzystać z zestawu testowego teraz? Naszym celem jest opracowanie i dostrojenie naszego modelu przy użyciu tylko danych uczących, a następnie wykorzystanie danych testowych tylko raz, aby ocenić naszą dokładność).
x_val = train_examples[:10000]
partial_x_train = train_examples[10000:]
y_val = train_labels[:10000]
partial_y_train = train_labels[10000:]
Trenuj modelkę
Trenuj model przez 40 epok w mini-partiach po 512 próbek. Jest to ponad 40 powtórzeń wszystkich próbek w x_train i y_train tensorów. Podczas uczenia monitoruj utratę i dokładność modelu na 10 000 próbek ze zbioru walidacyjnego:
history = model.fit(partial_x_train,
partial_y_train,
epochs=40,
batch_size=512,
validation_data=(x_val, y_val),
verbose=1)
Epoch 1/40 30/30 [==============================] - 2s 34ms/step - loss: 0.6667 - accuracy: 0.6060 - val_loss: 0.6192 - val_accuracy: 0.7195 Epoch 2/40 30/30 [==============================] - 1s 28ms/step - loss: 0.5609 - accuracy: 0.7770 - val_loss: 0.5155 - val_accuracy: 0.7882 Epoch 3/40 30/30 [==============================] - 1s 29ms/step - loss: 0.4309 - accuracy: 0.8489 - val_loss: 0.4135 - val_accuracy: 0.8364 Epoch 4/40 30/30 [==============================] - 1s 28ms/step - loss: 0.3154 - accuracy: 0.8937 - val_loss: 0.3515 - val_accuracy: 0.8583 Epoch 5/40 30/30 [==============================] - 1s 29ms/step - loss: 0.2345 - accuracy: 0.9227 - val_loss: 0.3256 - val_accuracy: 0.8639 Epoch 6/40 30/30 [==============================] - 1s 28ms/step - loss: 0.1773 - accuracy: 0.9457 - val_loss: 0.3104 - val_accuracy: 0.8702 Epoch 7/40 30/30 [==============================] - 1s 29ms/step - loss: 0.1331 - accuracy: 0.9645 - val_loss: 0.3024 - val_accuracy: 0.8741 Epoch 8/40 30/30 [==============================] - 1s 28ms/step - loss: 0.0984 - accuracy: 0.9777 - val_loss: 0.3061 - val_accuracy: 0.8758 Epoch 9/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0707 - accuracy: 0.9869 - val_loss: 0.3136 - val_accuracy: 0.8745 Epoch 10/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0501 - accuracy: 0.9919 - val_loss: 0.3305 - val_accuracy: 0.8743 Epoch 11/40 30/30 [==============================] - 1s 28ms/step - loss: 0.0351 - accuracy: 0.9960 - val_loss: 0.3434 - val_accuracy: 0.8726 Epoch 12/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0247 - accuracy: 0.9984 - val_loss: 0.3568 - val_accuracy: 0.8722 Epoch 13/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0178 - accuracy: 0.9993 - val_loss: 0.3711 - val_accuracy: 0.8700 Epoch 14/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0134 - accuracy: 0.9996 - val_loss: 0.3839 - val_accuracy: 0.8711 Epoch 15/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0103 - accuracy: 0.9998 - val_loss: 0.3968 - val_accuracy: 0.8701 Epoch 16/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0080 - accuracy: 0.9998 - val_loss: 0.4104 - val_accuracy: 0.8702 Epoch 17/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0063 - accuracy: 0.9999 - val_loss: 0.4199 - val_accuracy: 0.8694 Epoch 18/40 30/30 [==============================] - 1s 28ms/step - loss: 0.0051 - accuracy: 1.0000 - val_loss: 0.4305 - val_accuracy: 0.8691 Epoch 19/40 30/30 [==============================] - 1s 28ms/step - loss: 0.0043 - accuracy: 1.0000 - val_loss: 0.4403 - val_accuracy: 0.8688 Epoch 20/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0036 - accuracy: 1.0000 - val_loss: 0.4493 - val_accuracy: 0.8687 Epoch 21/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0031 - accuracy: 1.0000 - val_loss: 0.4580 - val_accuracy: 0.8682 Epoch 22/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0027 - accuracy: 1.0000 - val_loss: 0.4659 - val_accuracy: 0.8682 Epoch 23/40 30/30 [==============================] - 1s 31ms/step - loss: 0.0023 - accuracy: 1.0000 - val_loss: 0.4743 - val_accuracy: 0.8680 Epoch 24/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0020 - accuracy: 1.0000 - val_loss: 0.4808 - val_accuracy: 0.8678 Epoch 25/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0018 - accuracy: 1.0000 - val_loss: 0.4879 - val_accuracy: 0.8669 Epoch 26/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0016 - accuracy: 1.0000 - val_loss: 0.4943 - val_accuracy: 0.8667 Epoch 27/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0015 - accuracy: 1.0000 - val_loss: 0.5003 - val_accuracy: 0.8672 Epoch 28/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0013 - accuracy: 1.0000 - val_loss: 0.5064 - val_accuracy: 0.8665 Epoch 29/40 30/30 [==============================] - 1s 29ms/step - loss: 0.0012 - accuracy: 1.0000 - val_loss: 0.5120 - val_accuracy: 0.8668 Epoch 30/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0011 - accuracy: 1.0000 - val_loss: 0.5174 - val_accuracy: 0.8671 Epoch 31/40 30/30 [==============================] - 1s 30ms/step - loss: 0.0010 - accuracy: 1.0000 - val_loss: 0.5230 - val_accuracy: 0.8664 Epoch 32/40 30/30 [==============================] - 1s 29ms/step - loss: 9.2117e-04 - accuracy: 1.0000 - val_loss: 0.5281 - val_accuracy: 0.8663 Epoch 33/40 30/30 [==============================] - 1s 29ms/step - loss: 8.4693e-04 - accuracy: 1.0000 - val_loss: 0.5332 - val_accuracy: 0.8659 Epoch 34/40 30/30 [==============================] - 1s 30ms/step - loss: 7.8501e-04 - accuracy: 1.0000 - val_loss: 0.5376 - val_accuracy: 0.8666 Epoch 35/40 30/30 [==============================] - 1s 29ms/step - loss: 7.2613e-04 - accuracy: 1.0000 - val_loss: 0.5424 - val_accuracy: 0.8657 Epoch 36/40 30/30 [==============================] - 1s 29ms/step - loss: 6.7541e-04 - accuracy: 1.0000 - val_loss: 0.5468 - val_accuracy: 0.8659 Epoch 37/40 30/30 [==============================] - 1s 29ms/step - loss: 6.2841e-04 - accuracy: 1.0000 - val_loss: 0.5510 - val_accuracy: 0.8658 Epoch 38/40 30/30 [==============================] - 1s 29ms/step - loss: 5.8661e-04 - accuracy: 1.0000 - val_loss: 0.5553 - val_accuracy: 0.8656 Epoch 39/40 30/30 [==============================] - 1s 29ms/step - loss: 5.4869e-04 - accuracy: 1.0000 - val_loss: 0.5595 - val_accuracy: 0.8658 Epoch 40/40 30/30 [==============================] - 1s 30ms/step - loss: 5.1370e-04 - accuracy: 1.0000 - val_loss: 0.5635 - val_accuracy: 0.8659
Oceń model
Zobaczmy, jak sprawuje się model. Zwrócone zostaną dwie wartości. Strata (liczba, która reprezentuje nasz błąd, niższe wartości są lepsze) i dokładność.
results = model.evaluate(test_examples, test_labels)
print(results)
782/782 [==============================] - 2s 3ms/step - loss: 0.6272 - accuracy: 0.8484 [0.6272369027137756, 0.848360002040863]
To dość naiwne podejście osiąga dokładność około 87%. Przy bardziej zaawansowanych podejściach model powinien zbliżyć się do 95%.
Utwórz wykres dokładności i straty w czasie
model.fit() zwraca History obiektu, który zawiera słownik z wszystkiego, co wydarzyło się podczas szkolenia:
history_dict = history.history
history_dict.keys()
dict_keys(['loss', 'accuracy', 'val_loss', 'val_accuracy'])
Istnieją cztery wpisy: po jednym dla każdej metryki monitorowanej podczas uczenia i walidacji. Możemy ich użyć do wykreślenia straty treningu i walidacji w celu porównania, a także dokładności treningu i walidacji:
acc = history_dict['accuracy']
val_acc = history_dict['val_accuracy']
loss = history_dict['loss']
val_loss = history_dict['val_loss']
epochs = range(1, len(acc) + 1)
# "bo" is for "blue dot"
plt.plot(epochs, loss, 'bo', label='Training loss')
# b is for "solid blue line"
plt.plot(epochs, val_loss, 'b', label='Validation loss')
plt.title('Training and validation loss')
plt.xlabel('Epochs')
plt.ylabel('Loss')
plt.legend()
plt.show()
plt.clf() # clear figure
plt.plot(epochs, acc, 'bo', label='Training acc')
plt.plot(epochs, val_acc, 'b', label='Validation acc')
plt.title('Training and validation accuracy')
plt.xlabel('Epochs')
plt.ylabel('Accuracy')
plt.legend()
plt.show()
Na tym wykresie kropki reprezentują utratę i dokładność treningu, a linie ciągłe oznaczają utratę i dokładność walidacji.
Zauważ, że utrata szkolenia zmniejsza się z każdej epoki oraz szkolenia dokładność zwiększa się z każdej epoki. Jest to oczekiwane podczas korzystania z optymalizacji gradientu — powinno to minimalizować żądaną ilość w każdej iteracji.
Nie dotyczy to utraty i dokładności walidacji — wydaje się, że osiągają one szczyt po około dwudziestu epokach. Jest to przykład nadmiernego dopasowania: model działa lepiej na danych uczących niż na danych, których nigdy wcześniej nie widział. Po tym punkcie, model over-optymalizuje i dowiaduje się reprezentacje specyficzne dla danych treningowych, które nie uogólniać do danych testowych.
W tym konkretnym przypadku moglibyśmy zapobiec nadmiernemu dopasowaniu, po prostu przerywając trening po około dwudziestu epokach. Później zobaczysz, jak to zrobić automatycznie za pomocą wywołania zwrotnego.
# MIT License
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# Copyright (c) 2017 François Chollet
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