我在分类网络上使用小型游戏时尝试使用T.nnet.categorical_crossentropy作为成本函数。我无法将输入标签（例如Y数据）传递给成本函数。
看看：
"""
batch_size = 10
n_classes = 26
input_labels.shape = (10, 26)
"""
err_func = T.nnet.categorical_crossentropy
cost = err_func(output_layer, input_labels)
grads = T.grad(cost, params)
TypeError: cost must be a scalar.
cost = err_func(output_layer, np.array([T.arange(input_labels.shape[0]), input_labels]))
theano.tensor.var.AsTensorError: ("Cannot convert [ARange{dtype='int64'}.0 Y] to TensorType", <class 'numpy.ndarray'>)
cost = err_func(output_layer, theano.shared(np.array([T.arange(input_labels.shape[0]), input_labels])))
AttributeError: 'SharedVariable' object has no attribute 'ndim'
cost = err_func(output_layer, np.array([np.arange(input_labels.shape[0]), input_labels]))
TypeError: a float is required
如果需要，大多数其他代码：
import theano
from theano import tensor as T
# from theano.tensor.signal.downsample import max_pool_2d # deprecated
from theano.tensor.signal.pool import pool_2d
import numpy as np
import logging
from matplotlib import pyplot as plt
from net.net_utils import init_rand_weights, init_zero_weights
class ConvNet:
def __init__(self, layers, err_func, backprop_func, backprop_params,
l_rate, batch_size=10):
"""
:param layers:
:param err_func: cost/error function
:param backprop_func: backpropagation function
:param backprop_params: parameters to pass to backprop function
:param l_rate: learning rate
:param batch_size: (mini-) batch size. In comparison to regular nets
:return:
"""
self.batch_size = batch_size
logging.info('\tConstructing ANN with %s layers. Learning rate: %s. Batch size: %s ',
len(layers), l_rate, batch_size)
params = [] # Regular weights and bias weights; e.g. everything to be adjusted during training
for layer in layers:
for param in layer.params:
params.append(param)
logging.info('\tNumber of parameters to train: %s',
sum(param.get_value(borrow=True, return_internal_type=True).size for param in params))
input_data = T.fmatrix('X')
input_labels = T.fmatrix('Y')
layers[0].activate(input_data, batch_size)
for i in range(1, len(layers)):
prev_layer = layers[i-1]
current_layer = layers[i]
current_layer.activate(prev_layer.output(), batch_size)
output_layer = layers[-1].output_values
#cost = err_func(output_layer, input_labels)
cost = err_func(output_layer, theano.shared(np.array([T.arange(input_labels.shape[0]), input_labels])))
updates = backprop_func(cost, params, l_rate, **backprop_params)
prediction = T.argmax(output_layer, axis=1)
prediction_value = T.max(output_layer, axis=1)
logging.debug('\tConstructing functions ...')
self.trainer = theano.function(
inputs=[input_data, input_labels],
outputs=cost,
updates=updates,
name='Trainer',
allow_input_downcast=True # Allows float64 to be casted as float32, which is necessary in order to use GPU
)
self.predictor = theano.function(
inputs=[input_data],
outputs={'char_as_int': prediction,
'char_probability': prediction_value,
'output_layer': output_layer},
name='Predictor',
allow_input_downcast=True
)
def train_and_test(self, train_x, train_y, test_x, test_y, epochs=200, plot=True):
assert len(train_x) == len(train_y) and len(test_x) == len(test_y), \
("Training", len(train_x), len(train_y), "or testing", len(test_x), len(test_y),
"data sets does not have the same amount of data as classifications")
logging.info('\tTraining and testing for %s epochs ...', epochs)
"""
Both training and testing is done in batches for increased speed and to avoid running out of memory.
If len(train_x) % self.batch size != 0 then some training examples will not be trained on. The same applies to
testing.
"""
n_training_batches = len(train_x) // self.batch_size
n_testing_batches = len(test_x) // self.batch_size
train_success_rates = []
test_success_rates = []
for i in range(epochs):
for j in range(n_training_batches):
x_cases = train_x[j*self.batch_size:(j+1)*self.batch_size]
y_cases = train_y[j*self.batch_size:(j+1)*self.batch_size]
self.trainer(x_cases, y_cases)
# Get success rate on training and test data set
tr_result = np.zeros(shape=(n_training_batches*self.batch_size))
te_result = np.zeros(shape=(n_testing_batches*self.batch_size))
for k in range(n_training_batches):
batch = train_x[k*self.batch_size:(k+1)*self.batch_size]
tr_result[k*self.batch_size:(k+1)*self.batch_size] = self.predictor(batch)['char_as_int']
for l in range(n_testing_batches):
batch = test_x[l*self.batch_size:(l+1)*self.batch_size]
te_result[l*self.batch_size:(l+1)*self.batch_size] = self.predictor(batch)['char_as_int']
# logging.debug('\t\t\t\t L:%s:%s / %s, batch size %s', l, l+self.batch_size, len(test_x), len(batch))
# todo: verify that the length of each comparison result set is equal,
# and that the sets are equally 'full' (no missing values)
tr_success_rate = np.mean(np.argmax(train_y[:n_training_batches*self.batch_size], axis=1) == tr_result)
te_success_rate = np.mean(np.argmax(test_y[:n_testing_batches*self.batch_size], axis=1) == te_result)
train_success_rates.append(tr_success_rate)
test_success_rates.append(te_success_rate)
if i % (epochs / 20) == 0:
logging.info('\t\tProgress: %s%% | Epoch: %s | Success rate (training, test): %s, %s',
(i / epochs)*100, i,
"{:.4f}".format(max(train_success_rates)), "{:.4f}".format(max(test_success_rates)))
logging.info('\tMax success rate (training | test): %s | %s',
"{:.4f}".format(max(train_success_rates)), "{:.4f}".format(max(test_success_rates)))
if plot:
plt.title('Convolutional Pooled Net')
plt.plot(train_success_rates)
plt.plot(test_success_rates)
plt.legend(['Train', 'Test'], loc="best")
plt.grid(True)
plt.yticks(np.arange(0, 1, 0.05))
plt.show()
def predict(self, input_x):
return self.predictor(input_x)
class FullyConnectedLayer:
def __init__(self, n_in, n_out, act_func):
"""
Generate a fully connected layer with 1 bias node simulated upstream
:param act_func: the activation function of the layer
"""
self.n_in = n_in
self.n_out = n_out
self.act_func = act_func
self.weights = init_rand_weights((n_in, n_out), "w")
self.bias_weights = init_rand_weights((n_out,), "b")
self.params = [self.weights, self.bias_weights]
self.output_values = None
def activate(self, input_values, batch_size):
"""
:param input_values: the output from the upstream layer (which is input to this layer)
:param batch_size:
:return:
"""
input_values = input_values.reshape((batch_size, self.n_in))
self.output_values = self.act_func(T.dot(input_values, self.weights) + self.bias_weights)
def output(self):
assert self.output_values is not None, 'Asking for output before activating layer'
return self.output_values
class SoftMaxLayer(FullyConnectedLayer):
def __init__(self, n_in, n_out):
super(SoftMaxLayer, self).__init__(n_in, n_out, T.nnet.softmax)
# todo find out how to initialize softmaxlayer weights as zero, and if it gives better results/faster training
class ConvPoolLayer:
conv_func = staticmethod(T.nnet.conv2d)
pool_func = staticmethod(pool_2d)
def __init__(self, input_shape, n_feature_maps, act_func,
local_receptive_field_size=(5, 5), pool_size=(2, 2), pool_mode='max'):
"""
Generate a convolutional and a subsequent pooling layer with one bias node for each channel in the pooling layer.
:param input_shape: tuple(batch size, input channels, input rows, input columns) where
input_channels = number of feature maps in upstream layer
input rows, input columns = output size of upstream layer
:param n_feature_maps: number of feature maps/filters in this layer
:param local_receptive_field_size: (filter rows, filter columns) = size of local receptive field
:param pool_size: (rows, columns)
:param act_func: activation function to be applied to the output from the pooling layer
:param init_weight_func:
:param init_bias_weight_func:
"""
self.input_shape = input_shape
self.n_feature_maps = n_feature_maps
self.filter_shape = (n_feature_maps, input_shape[1]) + local_receptive_field_size
self.local_receptive_field_size = local_receptive_field_size
self.act_func = act_func
self.pool_size = pool_size
self.pool_mode = pool_mode
self.weights = init_rand_weights(self.filter_shape, "conv2poolWeights")
self.bias_weights = init_rand_weights((n_feature_maps,), "conv2poolBiasWeights")
self.params = [self.weights, self.bias_weights]
self.output_values = None
def activate(self, input_values, *args):
"""
:param input_values: the output from the upstream layer (which is input to this layer)
:return:
"""
input_values = input_values.reshape(self.input_shape)
conv = self.conv_func(
input=input_values,
input_shape=self.input_shape,
filters=self.weights,
filter_shape=self.filter_shape
)
pooled = self.pool_func(
input=conv,
ds=self.pool_size,
ignore_border=True, # If the pool size does not evenly divide the input,
# then ignoring the border will pool from padded zeros.
# This is usually the desired behaviour when max pooling.
# st=(1,1) # Stride size. Defaults to pool size, e.g. non-overlapping pooling regions
mode=self.pool_mode # ‘max’, ‘sum’, ‘average_inc_pad’ or ‘average_exc_pad’
)
self.output_values = self.act_func(pooled + self.bias_weights.dimshuffle('x', 0, 'x', 'x'))
def output(self):
assert self.output_values is not None, 'Asking for output before activating layer'
return self.output_values
@property
def output_shape(self):
batch_size = self.input_shape[0]
if self.local_receptive_field_size[0] != self.local_receptive_field_size[1] \
or self.pool_size[0] != self.pool_size[1]:
raise NotImplementedError("I don't know how to calculate output shape when the local receptive field,",
self.local_receptive_field_size, ", or the pool,",
self.pool_size, ", is non-square")
after_conv = self.input_shape[2] - self.local_receptive_field_size[0]
after_pool = int(np.ceil(after_conv/2.0))
shape = (batch_size, self.n_feature_maps, after_pool, after_pool)
return shape
答案 0 :(得分：1)
虽然我不确定它是多么理想，但这是有效的：
cost = T.mean(T.nnet.categorical_crossentropy(output_layer, input_labels))