Python functions.mean函数代码示例

def sigma_regularization(ctx, log_var, one):
    with nn.context_scope(ctx):
        h = F.exp(log_var)
        h = F.pow_scalar(h, 0.5)
        h = F.mean(h, axis=1)
        r = F.mean(F.squared_error(h, one))
    return r

def vat(x, r, eps, predict, distance):
    """
    Function for calculate LDS Loss, e.g. KL(p(y|x)||KL(p(y|x+n)

    Args:
        x(`~nnabla.Variable`): N-D array 
        r(`~nnabla.Variable`): N-D array of randn/grad
        eps(`~nnabla.Variable`): Scaling factor, xi for power iteration, epsilon for loss 
        predict: pointer of feed-forward-net building function
        distance: pointer of distance function e.g. KL(p(y|x)||KL(p(y|x+n)

    Returns:
        ~nnabla.Variable: LDS loss (KL(p(y|x)||KL(p(y|x+n))
    """
    # Calculate log(p(y|x))
    y = predict(x)

    # For stoping the backprop from this path.
    y1 = y.unlinked()

    # Calculate log(p(y|x+n))
    y2 = predict(x + eps * r)

    # Calculate kl(p(y|x)||p(y|x+n))
    loss = distance(y1, y2)
    loss = F.mean(loss)

    # Returns loss and y
    # y is returned for avoiding duplicated calculation
    return loss, y

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 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 kl_divergence(ctx, pred, label, log_var):
    with nn.context_scope(ctx):
        s = F.pow_scalar(F.exp(log_var), 0.5)
        elms = softmax_with_temperature(ctx, label, s) \
               * F.log(F.softmax(pred, axis=1))
        loss = -F.mean(F.sum(elms, axis=1))
    return loss

def sigmas_regularization(ctx, log_var0, log_var1):
    with nn.context_scope(ctx):
        h0 = F.exp(log_var0)
        h0 = F.pow_scalar(h0, 0.5)
        h1 = F.exp(log_var1)
        h1 = F.pow_scalar(h1, 0.5)
        r = F.mean(F.squared_error(h0, h1))
    return r

def sr_loss_with_uncertainty(ctx, pred0, pred1, log_var0, log_var1):
    #TODO: squared error/absolute error
    s0 = F.exp(log_var0)
    s1 = F.exp(log_var1)
    squared_error = F.squared_error(pred0, pred1)
    with nn.context_scope(ctx):
        loss_sr = F.mean(squared_error * (1 / s0 + 1 / s1) + (s0 / s1 + s1 / s0)) * 0.5
    return loss_sr

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 sr_loss_with_uncertainty(ctx, pred0, pred1, log_var0, log_var1):
    var0 = F.exp(log_var0)
    var1 = F.exp(log_var1)
    s0 = F.pow_scalar(var0, 0.5)
    s1 = F.pow_scalar(var0, 0.5)
    squared_error = F.squared_error(pred0, pred1)
    with nn.context_scope(ctx):
        loss = F.log(s1/s0) + (var0/var1 + squared_error/var1) * 0.5
        loss_sr = F.mean(loss)
    return loss_sr

def sr_loss_with_uncertainty(ctx, pred0, pred1, log_v0, log_v1, 
                             log_s0, log_s1):
    v0 = F.exp(log_v0)
    v1 = F.exp(log_v1)
    squared_error = F.squared_error(pred0, pred1)
    s0 = F.exp(log_s0)
    s1 = F.exp(log_s1)
    with nn.context_scope(ctx):
        error = squared_error * (1 / v0 + 1 / v1) + (v0 / v1 + v1 / v0) + (s0 / s1 + s1 / s0)
        loss_sr = F.mean(error) * 0.5
    return loss_sr

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 sr_loss_with_uncertainty_and_coef(ctx, pred0, pred1, log_var0, log_var1):
    c0 = srwu_learned_coef(ctx, log_var0)
    c1 = srwu_learned_coef(ctx, log_var1)
    sc0 = sigmas_learned_coef(ctx, log_var0, log_var1)
    sc1 = sigmas_learned_coef(ctx, log_var1, log_var0)
    c0.need_grad = False
    c1.need_grad = False
    sc0.need_grad = False
    sc1.need_grad = False

    #TODO: squared error/absolute error
    s0 = F.exp(log_var0)
    s1 = F.exp(log_var1)
    squared_error = F.squared_error(pred0, pred1)
    with nn.context_scope(ctx):
        loss_sr = F.mean(
            squared_error * (c0 / s0 + c1 / s1) + (sc0 * s0 / s1 + sc1 * s1 / s0)) * 0.5
    return loss_sr

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