Python functions.softmax_cross_entropy函数代码示例

def ce_loss_with_uncertainty(ctx, pred, y_l, log_var):
    r = F.randn(0., 1., log_var.shape)
    r = F.pow_scalar(F.exp(log_var), 0.5) * r
    h = pred + r
    with nn.context_scope(ctx):
        loss_ce = F.mean(F.softmax_cross_entropy(h, y_l))
    return loss_ce

def test_graph_logreg(seed):
    rng = np.random.RandomState(seed)
    x = nn.Variable([2, 3, 4], need_grad=True)
    w = nn.Variable([12, 5], need_grad=True)
    b = nn.Variable([5], need_grad=True)
    t = nn.Variable([2, 1])
    x.d = rng.randn(*x.shape)
    w.d = rng.randn(*w.shape)
    b.d = rng.randn(*b.shape)
    t.d = rng.randint(0, 5, size=t.shape)

    nn.set_default_context(nn.Context())

    # Forwardprop by definintion
    with nn.auto_forward():
        z = F.affine(x, w, b, 1)
        l = F.softmax_cross_entropy(z, t, 1)
        L = F.mean(l)

    # Backprop
    # Diff should be initialized since they are always accumulated
    x.g = 0
    w.g = 0
    b.g = 0
    L.backward(clear_buffer=True)
    x.g = rng.randn(*x.shape)

    inputs = [x, w, b]

    from nbla_test_utils import \
        compute_analytical_and_numerical_grad_graph as grads
    agrad, ngrad = grads(L, inputs, 1e-3)
    assert np.allclose(ngrad, agrad, atol=1e-2)

def test_graph_model(model, seed):
    np.random.seed(313)
    rng = np.random.RandomState(seed)
    x = nn.Variable([2, 3, 4, 4], need_grad=True)
    t = nn.Variable([2, 1])
    x.d = rng.randn(*x.shape)
    t.d = rng.randint(0, 5, size=t.shape)

    nn.set_default_context(nn.Context())

    # Forwardprop by definintion
    nn.clear_parameters()
    if model == "mlp":
        with nn.parameter_scope('fc1'):
            z = PF.affine(x, 3)
        z2 = F.relu(z, inplace=True)
        with nn.parameter_scope('fc2'):
            z3 = PF.affine(z2, 5)
    elif model == "recurrent":
        with nn.parameter_scope('fc1'):
            z = PF.affine(x, 3)
            z2 = F.relu(z, inplace=True)
        h = z2
        for _ in range(2):
            with nn.parameter_scope('fc2'):
                h = PF.affine(h, 3)
                h = F.relu(h, inplace=True)
        with nn.parameter_scope('fc3'):
            z3 = PF.affine(h, 5)
    elif model == "convolution":
        with nn.parameter_scope('conv1'):
            z = PF.convolution(x, 3, (2, 2))
            z2 = F.relu(z, inplace=True)
        with nn.parameter_scope('fc2'):
            z3 = PF.affine(z2, 5)
    else:
        raise ValueError()
    l = F.softmax_cross_entropy(z3, t, 1)
    L = F.mean(l)

    # Forwardprop
    L.forward(clear_no_need_grad=True)

    # Backprop
    # Diff should be initialized since they are always accumulated
    x.grad.zero()
    L.backward(clear_buffer=True)
    x.g = rng.randn(*x.shape)
    parameters = nn.get_parameters()
    for param in parameters.values():
        param.grad.zero()
    inputs = [x] + list(parameters.values())

    from nbla_test_utils import \
        compute_analytical_and_numerical_grad_graph as grads
    agrad, ngrad = grads(L, inputs, 1e-3)
    assert np.allclose(ngrad, agrad, atol=1.05e-2)

def test_forward_backward():
    batch_size, m, h, w = 4, 3, 32, 32
    extension_module = "cpu"
    device_id = 0
    ctx = extension_context(extension_module, device_id=device_id)

    x_l_data = np.random.randn(batch_size, m, h, w)
    y_l_data = (np.random.rand(batch_size, 1) * 10).astype(np.int32)
    x_l = nn.Variable(x_l_data.shape)
    y_l = nn.Variable(y_l_data.shape)
    x_l.d = x_l_data
    y_l.d = y_l_data
    pred = cnn_model_003(ctx, x_l)
    with nn.context_scope(ctx):
        loss = F.mean(F.softmax_cross_entropy(pred, y_l))

    loss.forward()
    loss.backward()

def get_model(args, num_classes, test=False, tiny=False):
    """
    Create computation graph and variables.

    Args:

        tiny: Tiny ImageNet mode if True.
    """
    data_size = 320
    nn_in_size = 224
    if tiny:
        data_size = 64
        nn_in_size = 56
    image = nn.Variable([args.batch_size, 3, data_size, data_size])
    label = nn.Variable([args.batch_size, 1])
    pimage = image_preprocess(image, nn_in_size)
    pred, hidden = model_resnet.resnet_imagenet(
        pimage, num_classes, args.num_layers, args.shortcut_type, test=test, tiny=tiny)
    loss = F.mean(F.softmax_cross_entropy(pred, label))
    Model = namedtuple('Model', ['image', 'label', 'pred', 'loss', 'hidden'])
    return Model(image, label, pred, loss, hidden)

def test_graph_clear_buffer(seed):
    np.random.seed(313)
    rng = np.random.RandomState(seed)
    x = nn.Variable([2, 3, 4, 4])
    t = nn.Variable([2, 1])
    x.d = rng.randn(*x.shape)
    t.d = rng.randint(0, 5, size=t.shape)

    # Network definition
    nn.set_default_context(nn.Context())
    nn.clear_parameters()
    x1 = x + 1
    x2 = x1 - 1
    with nn.parameter_scope('conv1'):
        z = PF.convolution(x2, 3, (2, 2))
        z2 = F.relu(z, inplace=True)
    with nn.parameter_scope('fc2'):
        z3 = PF.affine(z2, 5)
    l = F.softmax_cross_entropy(z3, t, 1)
    L = F.mean(l)

    # Forwardprop
    import tempfile
    import os
    tmpd = tempfile.mkdtemp()
    nn.save_parameters(os.path.join(tmpd, 'parameter.h5'))
    first = False
    for cnng in [False, True]:
        for cb in [False, True]:
            _ = nn.load_parameters(os.path.join(tmpd, 'parameter.h5'))
            for v in nn.get_parameters().values():
                v.grad.zero()
            L.forward(clear_no_need_grad=cnng)
            L.backward(clear_buffer=cb)
            if not first:
                first = True
                g = list(nn.get_parameters().values())[0].g.copy()
            else:
                g2 = list(nn.get_parameters().values())[0].g.copy()
                assert np.all(g == g2)

def ce_loss(ctx, pred, y_l):
    with nn.context_scope(ctx):
        loss_ce = F.mean(F.softmax_cross_entropy(pred, y_l))
    return loss_ce

def main():
    """
    Main script.

    Steps:
    * Get and set context.
    * Load Dataset
    * Initialize DataIterator.
    * Create Networks
    *   Net for Labeled Data
    *   Net for Unlabeled Data
    *   Net for Test Data
    * Create Solver.
    * Training Loop.
    *   Test
    *   Training
    *     by Labeled Data
    *       Calculate Cross Entropy Loss 
    *     by Unlabeled Data
    *       Estimate Adversarial Direction
    *       Calculate LDS Loss
    """

    args = get_args()

    # Get context.
    from nnabla.contrib.context import extension_context
    extension_module = args.context
    if args.context is None:
        extension_module = 'cpu'
    logger.info("Running in %s" % extension_module)
    ctx = extension_context(extension_module, device_id=args.device_id)
    nn.set_default_context(ctx)

    shape_x = (1, 28, 28)
    n_h = args.n_units
    n_y = args.n_class

    # Load MNist Dataset
    from mnist_data import MnistDataSource
    with MnistDataSource(train=True) as d:
        x_t = d.images
        t_t = d.labels
    with MnistDataSource(train=False) as d:
        x_v = d.images
        t_v = d.labels
    x_t = np.array(x_t / 256.0).astype(np.float32)
    x_t, t_t = x_t[:args.n_train], t_t[:args.n_train]
    x_v, t_v = x_v[:args.n_valid], t_v[:args.n_valid]

    # Create Semi-supervised Datasets
    x_l, t_l, x_u, _ = split_dataset(x_t, t_t, args.n_labeled, args.n_class)
    x_u = np.r_[x_l, x_u]
    x_v = np.array(x_v / 256.0).astype(np.float32)

    # Create DataIterators for datasets of labeled, unlabeled and validation
    di_l = DataIterator(args.batchsize_l, [x_l, t_l])
    di_u = DataIterator(args.batchsize_u, [x_u])
    di_v = DataIterator(args.batchsize_v, [x_v, t_v])

    # Create networks
    # feed-forward-net building function
    def forward(x, test=False):
        return mlp_net(x, n_h, n_y, test)

    # Net for learning labeled data
    xl = nn.Variable((args.batchsize_l,) + shape_x, need_grad=False)
    hl = forward(xl, test=False)
    tl = nn.Variable((args.batchsize_l, 1), need_grad=False)
    loss_l = F.mean(F.softmax_cross_entropy(hl, tl))

    # Net for learning unlabeled data
    xu = nn.Variable((args.batchsize_u,) + shape_x, need_grad=False)
    r = nn.Variable((args.batchsize_u,) + shape_x, need_grad=True)
    eps = nn.Variable((args.batchsize_u,) + shape_x, need_grad=False)
    loss_u, yu = vat(xu, r, eps, forward, distance)

    # Net for evaluating valiation data
    xv = nn.Variable((args.batchsize_v,) + shape_x, need_grad=False)
    hv = forward(xv, test=True)
    tv = nn.Variable((args.batchsize_v, 1), need_grad=False)

    # Create solver
    solver = S.Adam(args.learning_rate)
    solver.set_parameters(nn.get_parameters())

    # Monitor trainig and validation stats.
    import nnabla.monitor as M
    monitor = M.Monitor(args.model_save_path)
    monitor_verr = M.MonitorSeries("Test error", monitor, interval=240)
    monitor_time = M.MonitorTimeElapsed("Elapsed time", monitor, interval=240)

    # Training Loop.
    t0 = time.time()

    for i in range(args.max_iter):

        # Validation Test
        if i % args.val_interval == 0:
            n_error = calc_validation_error(
#.........这里部分代码省略.........

def train():
    """
    Main script.

    Steps:

    * Parse command line arguments.
    * Specify a context for computation.
    * Initialize DataIterator for MNIST.
    * Construct a computation graph for training and validation.
    * Initialize a solver and set parameter variables to it.
    * Create monitor instances for saving and displaying training stats.
    * Training loop
      * Computate error rate for validation data (periodically)
      * Get a next minibatch.
      * Execute forwardprop on the training graph.
      * Compute training error
      * Set parameter gradients zero
      * Execute backprop.
      * Solver updates parameters by using gradients computed by backprop.
    """
    args = get_args()

    # Get context.
    from nnabla.contrib.context import extension_context
    extension_module = args.context
    if args.context is None:
        extension_module = 'cpu'
    logger.info("Running in %s" % extension_module)
    ctx = extension_context(extension_module, device_id=args.device_id)
    nn.set_default_context(ctx)

    # Create CNN network for both training and testing.
    mnist_cnn_prediction = mnist_lenet_prediction
    if args.net == 'resnet':
        mnist_cnn_prediction = mnist_resnet_prediction

    # TRAIN
    # Create input variables.
    image = nn.Variable([args.batch_size, 1, 28, 28])
    label = nn.Variable([args.batch_size, 1])
    # Create prediction graph.
    pred = mnist_cnn_prediction(image, test=False)
    pred.persistent = True
    # Create loss function.
    loss = F.mean(F.softmax_cross_entropy(pred, label))

    # TEST
    # Create input variables.
    vimage = nn.Variable([args.batch_size, 1, 28, 28])
    vlabel = nn.Variable([args.batch_size, 1])
    # Create predition graph.
    vpred = mnist_cnn_prediction(vimage, test=True)

    # Create Solver.
    solver = S.Adam(args.learning_rate)
    solver.set_parameters(nn.get_parameters())

    # Create monitor.
    from nnabla.monitor import Monitor, MonitorSeries, MonitorTimeElapsed
    monitor = Monitor(args.monitor_path)
    monitor_loss = MonitorSeries("Training loss", monitor, interval=10)
    monitor_err = MonitorSeries("Training error", monitor, interval=10)
    monitor_time = MonitorTimeElapsed("Training time", monitor, interval=100)
    monitor_verr = MonitorSeries("Test error", monitor, interval=10)

    # Initialize DataIterator for MNIST.
    data = data_iterator_mnist(args.batch_size, True)
    vdata = data_iterator_mnist(args.batch_size, False)
    # Training loop.
    for i in range(args.max_iter):
        if i % args.val_interval == 0:
            # Validation
            ve = 0.0
            for j in range(args.val_iter):
                vimage.d, vlabel.d = vdata.next()
                vpred.forward(clear_buffer=True)
                ve += categorical_error(vpred.d, vlabel.d)
            monitor_verr.add(i, ve / args.val_iter)
        if i % args.model_save_interval == 0:
            nn.save_parameters(os.path.join(
                args.model_save_path, 'params_%06d.h5' % i))
        # Training forward
        image.d, label.d = data.next()
        solver.zero_grad()
        loss.forward(clear_no_need_grad=True)
        loss.backward(clear_buffer=True)
        solver.weight_decay(args.weight_decay)
        solver.update()
        e = categorical_error(pred.d, label.d)
        monitor_loss.add(i, loss.d.copy())
        monitor_err.add(i, e)
        monitor_time.add(i)

    ve = 0.0
    for j in range(args.val_iter):
        vimage.d, vlabel.d = vdata.next()
        vpred.forward(clear_buffer=True)
        ve += categorical_error(vpred.d, vlabel.d)
    monitor_verr.add(i, ve / args.val_iter)
#.........这里部分代码省略.........

def cifar10_resnet23_loss(pred, label):
    loss = F.mean(F.softmax_cross_entropy(pred, label))
    return loss