Rimodellare i tensori

Più avanti nel corso classificherai immagini di lettere della lingua dei segni usando una rete neurale. In alcuni casi, la rete accetterà tensori monodimensionali come input, ma i tuoi dati arriveranno sotto forma di immagini, che saranno tensori bidimensionali o tridimensionali a seconda che siano in scala di grigi o a colori.

La figura sotto mostra immagini in scala di grigi e a colori della lettera A nella lingua dei segni. Le due immagini sono già state importate e convertite negli array numpy gray_tensor e color_tensor. Rimodella questi array in vettori monodimensionali usando l'operazione reshape, che è stata importata per te da tensorflow. Nota che la forma di gray_tensor è 28x28 e la forma di color_tensor è 28x28x3.

This figure shows grayscale and color images of the sign language letter "A".

Questo esercizio fa parte del corso

Introduzione a TensorFlow in Python

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Istruzioni dell'esercizio

Rimodella gray_tensor da una matrice 28x28 a un vettore 784x1 chiamato gray_vector.
Rimodella color_tensor da un tensore 28x28x3 a un vettore 2352x1 chiamato color_vector.

Esercizio pratico interattivo

Prova a risolvere questo esercizio completando il codice di esempio.

# Reshape the grayscale image tensor into a vector
gray_vector = reshape(____, (____, 1))

# Reshape the color image tensor into a vector
color_vector = reshape(____, (____, ____))

Modifica ed esegui il codice

Questo esercizio fa parte del corso

Introduzione a TensorFlow in Python

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Before you can build advanced models in TensorFlow 2, you will first need to understand the basics. In this chapter, you’ll learn how to define constants and variables, perform tensor addition and multiplication, and compute derivatives. Knowledge of linear algebra will be helpful, but not necessary.

Exercise 1: Costanti e variabili Exercise 2: Definire i dati come costanti Exercise 3: Definire variabili Exercise 4: Operazioni di base Exercise 5: Eseguire moltiplicazioni elemento per elemento Exercise 6: Fare previsioni con la moltiplicazione di matrici Exercise 7: Sommare lungo le dimensioni di un tensore Exercise 8: Operazioni avanzate Exercise 9: Rimodellare i tensori

Esercizio in corso

Exercise 10: Ottimizzazione con i gradienti Exercise 11: Lavorare con dati di immagini

In this chapter, you will learn how to build, solve, and make predictions with models in TensorFlow 2. You will focus on a simple class of models – the linear regression model – and will try to predict housing prices. By the end of the chapter, you will know how to load and manipulate data, construct loss functions, perform minimization, make predictions, and reduce resource use with batch training.

Exercise 1: Input data Exercise 2: Load data using pandas Exercise 3: Setting the data type Exercise 4: Loss functions Exercise 5: Loss functions in TensorFlow Exercise 6: Modifying the loss function Exercise 7: Linear regression Exercise 8: Set up a linear regression Exercise 9: Train a linear model Exercise 10: Multiple linear regression Exercise 11: Batch training Exercise 12: Preparing to batch train Exercise 13: Training a linear model in batches

The previous chapters taught you how to build models in TensorFlow 2. In this chapter, you will apply those same tools to build, train, and make predictions with neural networks. You will learn how to define dense layers, apply activation functions, select an optimizer, and apply regularization to reduce overfitting. You will take advantage of TensorFlow's flexibility by using both low-level linear algebra and high-level Keras API operations to define and train models.

Exercise 1: Dense layers Exercise 2: The linear algebra of dense layers Exercise 3: The low-level approach with multiple examples Exercise 4: Using the dense layer operation Exercise 5: Activation functions Exercise 6: Binary classification problems Exercise 7: Multiclass classification problems Exercise 8: Optimizers Exercise 9: The dangers of local minima Exercise 10: Avoiding local minima Exercise 11: Training a network in TensorFlow Exercise 12: Initialization in TensorFlow Exercise 13: Defining the model and loss function Exercise 14: Training neural networks with TensorFlow

In the final chapter, you'll use high-level APIs in TensorFlow 2 to train a sign language letter classifier. You will use both the sequential and functional Keras APIs to train, validate, make predictions with, and evaluate models. You will also learn how to use the Estimators API to streamline the model definition and training process, and to avoid errors.

Exercise 1: Defining neural networks with Keras Exercise 2: The sequential model in Keras Exercise 3: Compiling a sequential model Exercise 4: Defining a multiple input model Exercise 5: Training and validation with Keras Exercise 6: Training with Keras Exercise 7: Metrics and validation with Keras Exercise 8: Overfitting detection Exercise 9: Evaluating models Exercise 10: Training models with the Estimators API Exercise 11: Preparing to train with Estimators Exercise 12: Defining Estimators Exercise 13: Congratulations!