Error when trying to implement mAP as metrics in yolov1 training using tensorflow - tensorflow

I am trying to implement mAP as the main metric for yolov1 training. It ran fine for several epochs and was able to give the mAP value along with its loss for each batch. but after several epochs, it would crash, and I can't figure out what was wrong.
This is the error code that I got:
InvalidArgumentError: in user code:
C:\Users\DeepLab\AppData\Local\Temp/ipykernel_11432/1408655327.py:105 mean_average_precision *
if iou > best_iou:
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\autograph\operators\control_flow.py:1172 if_stmt
_tf_if_stmt(cond, body, orelse, get_state, set_state, symbol_names, nouts)
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\autograph\operators\control_flow.py:1180 _tf_if_stmt
cond = _verify_tf_condition(cond, 'if statement')
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\autograph\operators\control_flow.py:139 _verify_tf_condition
cond = array_ops.reshape(cond, ())
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\util\dispatch.py:206 wrapper
return target(*args, **kwargs)
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\ops\array_ops.py:196 reshape
result = gen_array_ops.reshape(tensor, shape, name)
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\ops\gen_array_ops.py:8397 reshape
return reshape_eager_fallback(
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\ops\gen_array_ops.py:8422 reshape_eager_fallback
_result = _execute.execute(b"Reshape", 1, inputs=_inputs_flat, attrs=_attrs,
C:\Users\DeepLab\anaconda3\envs\GPU\lib\site-packages\tensorflow\python\eager\execute.py:59 quick_execute
tensors = pywrap_tfe.TFE_Py_Execute(ctx._handle, device_name, op_name,
InvalidArgumentError: Input to reshape is a tensor with 0 values, but the requested shape has 1 [Op:Reshape]
For calculating mAP, I use these functions:
intersection_over_union used to return iou in tensor type
convert_cellboxes used to return the label value measured from the shape of the image
cellboxes_to_boxes used to return the list of lists containing 6 values (class_idx, confident, x, y, w, h)
non_max_suppression used to return the filtered version of cellboxes_to_boxes output
get_bboxes used to return a list containing 7 value, img_idx, class_idx, confident, x, y, w, h). It will be used as an input to calculate mAP.
mean_average_precisions is used to calculate mAP.
def intersection_over_union(boxes_preds, boxes_labels, box_format="midpoint"):
if box_format == "midpoint":
box1_x1 = boxes_preds[..., 0:1] - boxes_preds[..., 2:3] / 2 ## ==> x - w / 2 for each grid in each image
box1_y1 = boxes_preds[..., 1:2] - boxes_preds[..., 3:4] / 2 ## ==> y - h / 2 for each grid in each image
box1_x2 = boxes_preds[..., 0:1] + boxes_preds[..., 2:3] / 2 ## ==> x + w / 2 for each grid in each image
box1_y2 = boxes_preds[..., 1:2] + boxes_preds[..., 3:4] / 2 ## ==> y + h / 2 for each grid in each image
box2_x1 = boxes_labels[..., 0:1] - boxes_labels[..., 2:3] / 2
box2_y1 = boxes_labels[..., 1:2] - boxes_labels[..., 3:4] / 2
box2_x2 = boxes_labels[..., 0:1] + boxes_labels[..., 2:3] / 2
box2_y2 = boxes_labels[..., 1:2] + boxes_labels[..., 3:4] / 2
if box_format == "corners":
box1_x1 = boxes_preds[..., 0:1]
box1_y1 = boxes_preds[..., 1:2]
box1_x2 = boxes_preds[..., 2:3]
box1_y2 = boxes_preds[..., 3:4] # (N, 1)
box2_x1 = boxes_labels[..., 0:1]
box2_y1 = boxes_labels[..., 1:2]
box2_x2 = boxes_labels[..., 2:3]
box2_y2 = boxes_labels[..., 3:4]
x1 = K.max((box1_x1, box2_x1))
y1 = K.max((box1_y1, box2_y1))
x2 = K.min((box1_x2, box2_x2))
y2 = K.min((box1_y2, box2_y2))
intersection = K.clip((x2-x1), min_value=0, max_value=abs(x2-x1)) * K.clip((y2-y1), min_value=0, max_value=abs(y2-y1))
#intersection = 2
box1_area = abs((box1_x2 - box1_x1) * (box1_y2 - box1_y1))
box2_area = abs((box2_x2 - box2_x1) * (box2_y2 - box2_y1))
return intersection / (box1_area + box2_area - intersection + 1e-6)
def convert_cellboxes(predictions, S=7): #array (n, 7, 7, 30) (n, 7 x 7, 30)
#batch_size = predictions.shape[0]
try:
n = batch_size
predictions = K.reshape(predictions, (n, 7, 7, 30))
except:
n = len(X_val)%batch_size
predictions = K.reshape(predictions, (n, 7, 7, 30))
bboxes1 = predictions[..., 21:25]
bboxes2 = predictions[..., 26:30]
scores = tf.concat(
(tf.expand_dims(predictions[..., 20], 0), tf.expand_dims(predictions[..., 25], 0)), axis=0 #(1, 7, 7, 2)
) ## (n, 7, 7, 2)
best_box = tf.expand_dims(K.argmax(scores, 0), -1)
#print(best_box)
best_boxes = bboxes1 * (1 - best_box) + best_box * bboxes2 ##(7, 7, 4)
cell_indices = tf.expand_dims(tf.tile(tf.range(start=0, limit=7, delta=1), (7,)), -1) # (49, 1) (1, 7, 7, 1)
cell_indices = tf.repeat(tf.reshape(cell_indices, (1, 7, 7, 1)), n, 0) ## reshape from (49, 1) to (n, 7, 7, 1)
best_boxes = tf.cast(best_boxes, tf.float32)
cell_indices = tf.cast(cell_indices, tf.float32)
x = 1 / S * (best_boxes[..., :1] + cell_indices)
y = 1 / S * (best_boxes[..., 1:2] + K.permute_dimensions(cell_indices, (0, 2, 1, 3)))
w_h = 1 / S * best_boxes[..., 2:4]
converted_bboxes = tf.concat((x, y, w_h), axis=-1) # dimensi terakhir = 4
predicted_class = tf.expand_dims(K.argmax(predictions[..., :20], -1), -1) #n, 7, 7, 1
best_confidence = tf.expand_dims(K.max((predictions[..., 20], predictions[..., 25]), 0), -1)
predicted_class = tf.cast(predicted_class, tf.float32)
best_confidence = tf.cast(best_confidence, tf.float32)
#print(predicted_class.shape)
#print(best_confidence.shape)
#print(converted_bboxes.shape)
converted_preds = tf.concat(
(predicted_class, best_confidence, converted_bboxes), -1 # n, 7, 7, 6
)
#print(converted_preds.shape)
return converted_preds
def cellboxes_to_boxes(out, S=7):
try:
n = batch_size
converted_pred = K.reshape(convert_cellboxes(out), (n, S * S, -1)) # (n, 49, 6)
except:
n = len(X_val)%batch_size
converted_pred = K.reshape(convert_cellboxes(out), (n, S * S, -1)) # (n, 49, 6)
#print(converted_pred.shape)
converted_pred = converted_pred.numpy() # mode graph
all_bboxes = []
for ex_idx in range(out.shape[0]):
bboxes = []
for bbox_idx in range(S * S):
bboxes.append([x for x in converted_pred[ex_idx, bbox_idx, :]])
all_bboxes.append(bboxes)
return all_bboxes
def non_max_suppression(bboxes, iou_threshold, threshold, box_format="midpoint"):
#bboxes = bboxes[0]
#print(bboxes[:2])
#for i, box in enumerate(bboxes):
# bboxes[i][4:6] = box[4:6] * 7
#print(bboxes[:2])
assert type(bboxes) == list
bboxes = [box for box in bboxes if box[1] > threshold]
bboxes = sorted(bboxes, key=lambda x: x[1], reverse=True)
bboxes_after_nms = []
while bboxes:
chosen_box = bboxes.pop(0)
bboxes = [
box # (6)
for box in bboxes
if box[0] != chosen_box[0]
or intersection_over_union(
tf.constant(box[2:]),
tf.constant(chosen_box[2:]),
box_format=box_format,
)
< iou_threshold
]
bboxes_after_nms.append(chosen_box)
return bboxes_after_nms
def get_bboxes(gt_labels, pred_labels, iou_threshold, threshold, box_format="midpoint"):
"""
return:
images_pred_boxes = list with each element in this format (image_idx, class_prediction, prob_score, x, y, w, h)
images_gt_boxes = list with each element in this format (image_idx, class, prob_score, x, y, w, h)
"""
images_pred_boxes = []
images_gt_boxes = []
#pred_labels = model.predict(images) # data training, validation, testing
image_idx = 0
gt_boxes = cellboxes_to_boxes(gt_labels)
pred_boxes = cellboxes_to_boxes(pred_labels)
for i in range(len(gt_labels)):
pred_box_nms = non_max_suppression(pred_boxes[i], iou_threshold, threshold, box_format="midpoint")
for nms_box in pred_box_nms:
images_pred_boxes.append([image_idx] + nms_box)
for box in gt_boxes[i]:
if box[1] > threshold:
images_gt_boxes.append([image_idx] + box)
image_idx += 1
#print(images_pred_boxes[:10])
#print(images_gt_boxes[:10])
return images_pred_boxes, images_gt_boxes
def mean_average_precision(
y_true, y_pred, iou_threshold=0.5, box_format="midpoint", num_classes=20
):
pred_boxes, true_boxes = get_bboxes(y_true, y_pred, iou_threshold=0.6, threshold=0.3, box_format="midpoint")
# list storing all AP for respective classes
average_precisions = []
# used for numerical stability later on
epsilon = 1e-6
for c in range(num_classes):
detections = []
ground_truths = []
# Go through all predictions and targets,
# and only add the ones that belong to the
# current class c
for detection in pred_boxes:
if detection[1] == c:
detections.append(detection)
for true_box in true_boxes:
if true_box[1] == c:
ground_truths.append(true_box)
# find the amount of bboxes for each training example
# Counter here finds how many ground truth bboxes we get
# for each training example, so let's say img 0 has 3,
# img 1 has 5 then we will obtain a dictionary with:
# amount_bboxes = {0:3, 1:5, ..., 20: 10}
amount_bboxes = Counter([gt[0] for gt in ground_truths])
# We then go through each key, val in this dictionary
# and convert to the following (w.r.t same example):
# amount_bboxes = {0:torch.tensor[0,0,0], 1:torch.tensor[0,0,0,0,0]}
for key, val in amount_bboxes.items():
amount_bboxes[key] = np.zeros(val)
# sort by box probabilities which is index 2
detections.sort(key=lambda x: x[2], reverse=True)
TP = np.zeros((len(detections)))
FP = np.zeros((len(detections)))
total_true_bboxes = len(ground_truths)
# If none exists for this class then we can safely skip
if total_true_bboxes == 0:
continue
for detection_idx, detection in enumerate(detections):
# Only take out the ground_truths that have the same
# training idx as detection
ground_truth_img = [
bbox for bbox in ground_truths if bbox[0] == detection[0]
]
num_gts = len(ground_truth_img) #
best_iou = 0
best_gt_idx = 0
iou = 0
for idx, gt in enumerate(ground_truth_img):
iou = intersection_over_union(
tf.constant(detection[3:]),
tf.constant(gt[3:]),
box_format=box_format,
)
if iou > best_iou:
best_iou = iou
best_gt_idx = idx
if best_iou > iou_threshold:
# only detect ground truth detection once
if amount_bboxes[detection[0]][best_gt_idx] == 0:
# true positive and add this bounding box to seen
TP[detection_idx] = 1
amount_bboxes[detection[0]][best_gt_idx] = 1
else:
FP[detection_idx] = 1
# if IOU is lower then the detection is a false positive
else:
FP[detection_idx] = 1
TP = tf.constant(TP)
FP = tf.constant(FP)
#print(TP)
#print(FP)
TP_cumsum = tf.cumsum(TP, axis=0)
FP_cumsum = tf.cumsum(FP, axis=0)
recalls = TP_cumsum / (total_true_bboxes + epsilon)
precisions = tf.math.divide(TP_cumsum, (TP_cumsum + FP_cumsum + epsilon))
precisions = tf.concat((tf.cast(tf.constant([1]), precisions.dtype), precisions), axis=0)
recalls = tf.concat((tf.cast(tf.constant([0]), recalls.dtype), recalls), axis=0)
# torch.trapz for numerical integration
average_precisions.append(tfp.math.trapz(precisions, recalls))
return sum(average_precisions) / len(average_precisions)
for training, I used a standard model.fit with pascalvoc2007 as its dataset and a batch size of 4.

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when i doing such operation, training model 's time is very long;how to speed it.thanks
This code works:
# tensor = tf.constant([[[1,1],[2,2],[3,3],[4,4],[5,5]],[[1,1],[2,2],[3,3],[4,4],[5,5]],[[1,1],[2,2],[3,3],[4,4],[5,5]]] )
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res = tf.reduce_sum(res)
output.append(res)
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I tried to use tf.scan(), but I don't see any benefits:
output = tf.constant([], tf.int32)
for begins in range(length):
t = tensor[:, begins:, :]
t = tf.transpose(t, (1, 0, 2))
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Edits:
Tried to apply reduce_sum() along the unused dimension [0, 2] in preprocessing:
tensor = tf.reduce_sum(tensor, [0, 2])
output = tf.constant([])
for begins in range(length):
t = tensor[begins:]
t = tf.scan(lambda a, x: a + x, t)
output = tf.concat([output, t], 0)
Still don't see performance benefits.
for i in range(0,50):
for j in range(1,200):
if j + i < 200:
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TypeError when trying to make a loop creating artificial neural networks

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class LSTMLikeLayer(tf.keras.layers.Layer):
def __init__(self, n_inputs, n_outputs, activation):
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def _get_function(name):
f = None
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f = tf.nn.tanh
elif name == "sigmoid":
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elif name == "relu":
f = tf.nn.relu
elif not name:
f = tf.identity
assert f is not None
return f
# Sampling
def sampler(N1, N2, N3):
np.random.seed(42)
# Sampler #1: PDE domain
t1 = np.random.uniform(low=T0,
high=T,
size=[N1,1])
s1 = np.random.uniform(low=S1,
high=S2,
size=[N1,1])
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t2 = np.zeros(shape=(1, 1))
s2 = np.zeros(shape=(1, 1))
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t3 = T * np.ones((N3,1)) #Terminal condition
s3 = np.random.uniform(low=S1,
high=S2,
size=[N3,1])
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# Loss term #1: PDE
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V_x = tf.gradients(V, x1)[0]
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#L2 = tf.reduce_mean(tf.square(V))
# Loss term #3: initial/terminal condition
L3 = tf.reduce_mean(tf.square(model(t3, x3) - tf.math.maximum(x3-K,0)))
return (L1, L3)
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def analytical_solution(t, x):
#C = SN(d1) - Xe- rt N(d2)
#S: spot price
#K: strike price
#T: time to maturity
#r: interest rate
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np.random.seed(42)
tf.random.set_seed(42)
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K = 0.5
# PDE parameters
r = 0.05 # Interest rate
sigma = 0.25 # Volatility
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T0 = 0.0 + 1e-10 # Initial time
T = 1.0 # Terminal time
# Space limits
S1 = 0.0 + 1e-10 # Low boundary
S2 = 1.0 # High boundary
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NS_1 = 1000
NS_2 = 0
NS_3 = 100
t1, s1, t2, s2, t3, s3 = sampler(NS_1, NS_2, NS_3)
Now what I want to do is to iterate over different parameters and create a new ann for each iteration.
My plan was to do it in this way:
tf.compat.v1.disable_eager_execution()
t1_t = tf.compat.v1.placeholder(tf.float32, [None,1])
x1_t = tf.compat.v1.placeholder(tf.float32, [None,1])
t2_t = tf.compat.v1.placeholder(tf.float32, [None,1])
x2_t = tf.compat.v1.placeholder(tf.float32, [None,1])
t3_t = tf.compat.v1.placeholder(tf.float32, [None,1])
x3_t = tf.compat.v1.placeholder(tf.float32, [None,1])
volatility_list = [0.08]#[0.08, 0.16, 0.18, 0.2, 0.28]
stages_list = [10]#, 50, 100]
layers_list = [3]#, 5, 7]
npl_list = [3]#, 6, 9, 12, 15]
for sigma in volatility_list:
for st in stages_list:
for lay in layers_list:
for npl in npl_list:
# Neural Network definition
num_layers = lay
nodes_per_layer = npl
ann = DGMNet(num_layers, nodes_per_layer)
L1_t, L3_t = loss(ann, t1_t, x1_t, t2_t, x2_t, t3_t, x3_t)
loss_t = L1_t + L3_t
# Optimizer parameters
global_step = tf.Variable(1, trainable=False)
starter_learning_rate = 0.001
learning_rate = tf.compat.v1.train.exponential_decay(starter_learning_rate, global_step,
100000, 0.96, staircase=True)
optimizer = tf.compat.v1.train.AdamOptimizer(learning_rate=learning_rate).minimize(loss_t)
# Training parameters
steps_per_sample = st
sampling_stages = 100#2000
# Plot tensors
tplot_t = tf.compat.v1.placeholder(tf.float32, [None,1], name="tplot_t") # We name to recover it later
xplot_t = tf.compat.v1.placeholder(tf.float32, [None,1], name="xplot_t")
vplot_t = tf.identity(ann(tplot_t, xplot_t), name="vplot_t") # Trick for naming the trained model
# Training data holders
sampling_stages_list = []
elapsed_time_list = []
loss_list = []
L1_list = []
L3_list = []
# Train network!!
init_op = tf.compat.v1.global_variables_initializer()
sess = tf.compat.v1.Session()
sess.run(init_op)
for i in range(sampling_stages):
t1, x1, t2, x2, t3, x3 = sampler(NS_1, NS_2, NS_3)
start_time = time.clock()
for _ in range(steps_per_sample):
loss, L1, L3, _ = sess.run([loss_t, L1_t, L3_t, optimizer],
feed_dict = {t1_t:t1, x1_t:x1, t2_t:t2, x2_t:x2, t3_t:t3, x3_t:x3})
end_time = time.clock()
elapsed_time = end_time - start_time
sampling_stages_list.append(i)
elapsed_time_list.append(elapsed_time)
loss_list.append(loss)
L1_list.append(L1)
L3_list.append(L3)
text = "Stage: {:04d}, Loss: {:e}, L1: {:e}, L3: {:e}, {:f} seconds".format(i, loss, L1, L3, elapsed_time)
print(text)
#goodness of fit
time_0 = 0
listofzeros = [time_0] * 100
prices_for_goodness = np.linspace(S1,S2, 100)
goodness_list = []
solution_goodness = analytical_solution(listofzeros, prices_for_goodness)
ttt = time_0*np.ones_like(prices_for_goodness.reshape(-1,1))
nn_goodness, = sess.run([vplot_t],
feed_dict={tplot_t:ttt, xplot_t:prices_for_goodness.reshape(-1,1)})
deviation_list = np.abs(solution_goodness - nn_goodness)/(T-T0)
print("{0:.2f}%".format(np.average(deviation_list)*100))
Unfortunately as soon as it ends the first iteration I get a TypeError that 'numpy.float32' object is not callable
Error Traceback:
TypeError Traceback (most recent call last)
<ipython-input-14-bb14643d0c42> in <module>()
10
11
---> 12 L1_t, L3_t = loss(ann, t1_t, x1_t, t2_t, x2_t, t3_t, x3_t)
13 loss_t = L1_t + L3_t
14
TypeError: 'numpy.float32' object is not callable
I guess that the problem is with the creation of the placeholders, however I am not sure how to solve it. Maybe one of you can help me
Thanks in advance!
Chris
Did you create a variable called 'loss'? It seems that the loss function is redefined by a variable with the same name, so then python tries to call that variable as a function.

Deep neural-network with backpropagation implementation does not work - python

I want to implement a multilayer NN with backpropagation. I have been trying for days, but it simply does not work. It is extremely clear in my head how it is supposed to work, I have streamline my code to be as simple as possible but I can't do it. It's probably something stupid, but I cannot see it.
The implementation I have done is with an input layer of 784 (28x28), two (L) hidden layers of 300 and an output of 10 classes. I have a bias in every layer (except last...)
The output activation is softmax and the hidden activation is ReLU.
I use mini batches of 600 examples over a dataset of 60k examples with 50 to 500 epoches.
Here the core of my code:
Preparation:
from tensorflow import keras
import numpy as np
import matplotlib.pyplot as plt
fashion_mnist = keras.datasets.fashion_mnist
(train_images, train_labels), (test_images, test_labels) = fashion_mnist.load_data()
L = 2
K = len(np.unique(train_labels))
lr = 0.001
nb_epochs = 50
node_per_hidden_layer = 300
nb_batches = 100
W = []
losses_test = []
X_train = np.reshape(train_images, (train_images.shape[0], train_images.shape[1]*train_images.shape[2]))
X_test = np.reshape(test_images, (test_images.shape[0], train_images.shape[1]*train_images.shape[2]))
Y_train = np.zeros((train_labels.shape[0], K))
Y_train[np.arange(Y_train.shape[0]), train_labels] = 1
Y_test = np.zeros((test_labels.shape[0], K))
Y_test[np.arange(Y_test.shape[0]), test_labels] = 1
W.append(np.random.normal(0, 0.01, (X_train.shape[1]+1, node_per_hidden_layer)))
for i in range(L-1):
W.append(np.random.normal(0, 0.01, (node_per_hidden_layer+1, node_per_hidden_layer)))
W.append(np.random.normal(0, 0.01, (node_per_hidden_layer+1, K)))
Helper function:
def softmax(z):
exp = np.exp(z - z.max(1)[:,np.newaxis])
return np.array(exp / exp.sum(1)[:,np.newaxis])
def softmax_derivative(z):
sm = softmax(z)
return sm * (1-sm)
def ReLU(z):
return np.maximum(z, 0)
def ReLU_derivative(z):
return (z >= 0).astype(int)
def get_loss(y, y_pred):
return -np.sum(y * np.log(y_pred))
fitting
def fit():
minibatch_size = len(X_train) // nb_batches
for epoch in range(nb_epochs):
permutaion = list(np.random.permutation(X_train.shape[0]))
X_shuffle = X_train[permutaion]
Y_shuffle = Y_train[permutaion]
print("Epoch----------------", epoch)
for batche in range(0, X_shuffle.shape[0], minibatch_size):
Z = [None] * (L + 2)
a = [None] * (L + 2)
delta = [None] * (L + 2)
X = X_train[batche:batche+minibatch_size]
Y = Y_shuffle[batche:batche+minibatch_size]
### forward propagation
a[0] = np.append(X, np.ones((minibatch_size, 1)), axis=1)
for i in range(L):
Z[i + 1] = a[i] # W[i]
a[i + 1] = np.append(ReLU(Z[i+1]), np.ones((minibatch_size, 1), dtype=int), axis=1)
Z[-1] = a[L] # W[L]
a[-1] = softmax(Z[-1])
### back propagation
delta[-1] = (Y - a[-1]) * softmax_derivative(Z[-1])
for i in range(L, 0, -1):
delta[i] = (delta[i+1] # W[i].T)[:,:-1] * ReLU_derivative(Z[i])
for i in range(len(W)):
g = a[i].T # delta[i+1] / minibatch_size
W[i] = W[i] + lr * g
get_loss_on_test()
loss
def get_loss_on_test():
Z_test = [None] * (L + 2)
a_test = [None] * (L + 2)
a_test[0] = np.append(X_test, np.ones((len(X_test), 1)), axis=1)
for i in range(L):
Z_test[i + 1] = a_test[i] # W[i]
a_test[i + 1] = np.append(ReLU(Z_test[i+1]), np.ones((len(X_test), 1)), axis=1)
Z_test[-1] = a_test[L] # W[L]
a_test[-1] = softmax(Z_test[-1])
losses_test.append(get_loss(Y_test, a_test[-1]))
main
losses_test.clear()
fit()
plt.plot(losses_test)
plt.show()
If you want to see it in my notebook with an example of losses graph, here the link: https://github.com/beurnii/INF8225/blob/master/tp2/jpt.ipynb
If you want more details on my assignment, this is part 1b (page 2 for english):
https://github.com/beurnii/INF8225/blob/master/tp2/INF8225_TP2_2020.pdf

Why does the cost in my implementation of a deep neural network increase after a few iterations?

I am a beginner in machine learning and neural networks. Recently, after watching Andrew Ng's lectures on deep learning, I tried to implement a binary classifier using deep neural networks on my own.
However, the cost of the function is expected to decrease after each iteration.
In my program, it decreases slightly in the beginning, but rapidly increases later. I tried to make changes in learning rate and number of iterations, but to no avail. I am very confused.
Here is my code
1. Neural network classifier class
class NeuralNetwork:
def __init__(self, X, Y, dimensions, alpha=1.2, iter=3000):
self.X = X
self.Y = Y
self.dimensions = dimensions # Including input layer and output layer. Let example be dimensions=4
self.alpha = alpha # Learning rate
self.iter = iter # Number of iterations
self.length = len(self.dimensions)-1
self.params = {} # To store parameters W and b for each layer
self.cache = {} # To store cache Z and A for each layer
self.grads = {} # To store dA, dZ, dW, db
self.cost = 1 # Initial value does not matter
def initialize(self):
np.random.seed(3)
# If dimensions is 4, then layer 0 and 3 are input and output layers
# So we only need to initialize w1, w2 and w3
# There is no need of w0 for input layer
for l in range(1, len(self.dimensions)):
self.params['W'+str(l)] = np.random.randn(self.dimensions[l], self.dimensions[l-1])*0.01
self.params['b'+str(l)] = np.zeros((self.dimensions[l], 1))
def forward_propagation(self):
self.cache['A0'] = self.X
# For last layer, ie, the output layer 3, we need to activate using sigmoid
# For layer 1 and 2, we need to use relu
for l in range(1, len(self.dimensions)-1):
self.cache['Z'+str(l)] = np.dot(self.params['W'+str(l)], self.cache['A'+str(l-1)]) + self.params['b'+str(l)]
self.cache['A'+str(l)] = relu(self.cache['Z'+str(l)])
l = len(self.dimensions)-1
self.cache['Z'+str(l)] = np.dot(self.params['W'+str(l)], self.cache['A'+str(l-1)]) + self.params['b'+str(l)]
self.cache['A'+str(l)] = sigmoid(self.cache['Z'+str(l)])
def compute_cost(self):
m = self.Y.shape[1]
A = self.cache['A'+str(len(self.dimensions)-1)]
self.cost = -1/m*np.sum(np.multiply(self.Y, np.log(A)) + np.multiply(1-self.Y, np.log(1-A)))
self.cost = np.squeeze(self.cost)
def backward_propagation(self):
A = self.cache['A' + str(len(self.dimensions) - 1)]
m = self.X.shape[1]
self.grads['dA'+str(len(self.dimensions)-1)] = -(np.divide(self.Y, A) - np.divide(1-self.Y, 1-A))
# Sigmoid derivative for final layer
l = len(self.dimensions)-1
self.grads['dZ' + str(l)] = self.grads['dA' + str(l)] * sigmoid_prime(self.cache['Z' + str(l)])
self.grads['dW' + str(l)] = 1 / m * np.dot(self.grads['dZ' + str(l)], self.cache['A' + str(l - 1)].T)
self.grads['db' + str(l)] = 1 / m * np.sum(self.grads['dZ' + str(l)], axis=1, keepdims=True)
self.grads['dA' + str(l - 1)] = np.dot(self.params['W' + str(l)].T, self.grads['dZ' + str(l)])
# Relu derivative for previous layers
for l in range(len(self.dimensions)-2, 0, -1):
self.grads['dZ'+str(l)] = self.grads['dA'+str(l)] * relu_prime(self.cache['Z'+str(l)])
self.grads['dW'+str(l)] = 1/m*np.dot(self.grads['dZ'+str(l)], self.cache['A'+str(l-1)].T)
self.grads['db'+str(l)] = 1/m*np.sum(self.grads['dZ'+str(l)], axis=1, keepdims=True)
self.grads['dA'+str(l-1)] = np.dot(self.params['W'+str(l)].T, self.grads['dZ'+str(l)])
def update_parameters(self):
for l in range(1, len(self.dimensions)):
self.params['W'+str(l)] = self.params['W'+str(l)] - self.alpha*self.grads['dW'+str(l)]
self.params['b'+str(l)] = self.params['b'+str(l)] - self.alpha*self.grads['db'+str(l)]
def train(self):
np.random.seed(1)
self.initialize()
for i in range(self.iter):
#print(self.params)
self.forward_propagation()
self.compute_cost()
self.backward_propagation()
self.update_parameters()
if i % 100 == 0:
print('Cost after {} iterations is {}'.format(i, self.cost))
2. Testing code for odd or even number classifier
import numpy as np
from main import NeuralNetwork
X = np.array([[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]])
Y = np.array([[1, 0, 1, 0, 1, 0, 1, 0, 1, 0]])
clf = NeuralNetwork(X, Y, [1, 1, 1], alpha=0.003, iter=7000)
clf.train()
3. Helper Code
import math
import numpy as np
def sigmoid_scalar(x):
return 1/(1+math.exp(-x))
def sigmoid_prime_scalar(x):
return sigmoid_scalar(x)*(1-sigmoid_scalar(x))
def relu_scalar(x):
if x > 0:
return x
else:
return 0
def relu_prime_scalar(x):
if x > 0:
return 1
else:
return 0
sigmoid = np.vectorize(sigmoid_scalar)
sigmoid_prime = np.vectorize(sigmoid_prime_scalar)
relu = np.vectorize(relu_scalar)
relu_prime = np.vectorize(relu_prime_scalar)
Output
I believe your cross-entropy derivative is wrong. Instead of this:
# WRONG!
self.grads['dA'+str(len(self.dimensions)-1)] = -(np.divide(self.Y, A) - np.divide(1-self.Y, A))
... do this:
# CORRECT
self.grads['dA'+str(len(self.dimensions)-1)] = np.divide(A - self.Y, (1 - A) * A)
See these lecture notes for the details. I think you meant the formula (5), but forgot 1-A. Anyway, use formula (6).

Tensorflow : train on mini batch, fast then slow

I am a beginner in tensorflow and I am trying to train a model using "mini batch". To do that I created a generator and iterate it. The problem I encounter is that, at the beginning of the epoch, the train seems fast (many batch per seconds) then the train slow down (1 batch per second) so I am wondering where I am wrong in my code but I do not find the problem.
def prepare_data(filename):
'''load file which give path and label for the data'''
f = open(filename, 'r')
data = [line.split() for line in f]
feat =[]
label=[]
for l in data:
feat.append(l[0])
label.append(l[1])
n_samples = len(feat)
shuf = list(range(n_samples))
random.shuffle(shuf)
count = Counter(label)
print(count)
feature = [feat[i] for i in shuf]
label = np.array(label, dtype=np.int)
return feature, label[shuf]
def get_specgrams(paths, nsamples=16000):
'''
Given list of paths, return specgrams.
'''
# read the wav files
wavs = [wavfile.read(x)[1] for x in paths]
# zero pad the shorter samples and cut off the long ones.
data = []
for wav in wavs:
if wav.size < 16000:
d = np.pad(wav, (nsamples - wav.size, 0), mode='constant')
else:
d = wav[0:nsamples]
data.append(d)
# get the specgram
#specgram = [signal.spectrogram(d, nperseg=256, noverlap=128)[2] for d in data]
#specgram = [s.reshape(129, 124, -1) for s in specgram]
return np.asarray(data)
def get_specgram(path, nsamples=16000):
'''
Given path, return specgrams.
'''
# read the wav files
wav = wavfile.read(path)[1]
# zero pad the shorter samples and cut off the long ones.
if wav.size < 16000:
d = np.pad(wav, (nsamples - wav.size, 0), mode='constant')
else:
d = wav[0:nsamples]
# get the specgram
#specgram = [signal.spectrogram(d, nperseg=256, noverlap=128)[2] for d in data]
#specgram = [s.reshape(129, 124, -1) for s in specgram]
return d
# multci classification binary labels
def one_hot_encode(labels, n_unique_labels=31):
n_labels = len(labels)
#print('number of unique labels:', n_unique_labels)
one_hot_encode = np.zeros((n_labels,n_unique_labels))
one_hot_encode[np.arange(n_labels), labels] = 1
return np.array(one_hot_encode, dtype=np.int)
#create_path_file('train/audio/')
def model(tr_features, tr_labels, ts_features, ts_labels):
# remove gpu device error
config = tf.ConfigProto(allow_soft_placement = True)
# parameters
BATCH_SIZE = 4
number_loop = math.ceil(len(tr_features)/BATCH_SIZE)
training_epochs = 10
n_dim = 16000
n_classes = 31 #len(np.unique(ts_labels))
n_hidden_units_one = 280
n_hidden_units_two = 300
sd = 1 / np.sqrt(n_dim)
learning_rate = 0.1
# get test data
ts_features, ts_labels = get_data(ts_features, ts_labels)
# Model
X = tf.placeholder(tf.float32,[None,n_dim])
Y = tf.placeholder(tf.float32,[None,n_classes])
W_1 = tf.Variable(tf.random_normal([n_dim,n_hidden_units_one], mean = 0, stddev=sd))
b_1 = tf.Variable(tf.random_normal([n_hidden_units_one], mean = 0, stddev=sd))
h_1 = tf.nn.tanh(tf.matmul(X,W_1) + b_1)
W_2 = tf.Variable(tf.random_normal([n_hidden_units_one,n_hidden_units_two], mean = 0, stddev=sd))
b_2 = tf.Variable(tf.random_normal([n_hidden_units_two], mean = 0, stddev=sd))
h_2 = tf.nn.sigmoid(tf.matmul(h_1,W_2) + b_2)
W = tf.Variable(tf.random_normal([n_hidden_units_two,n_classes], mean = 0, stddev=sd))
b = tf.Variable(tf.random_normal([n_classes], mean = 0, stddev=sd))
y_ = tf.nn.softmax(tf.matmul(h_2,W) + b)
init = tf.initialize_all_variables()
# function and optimizers
cost_function = -tf.reduce_sum(Y * tf.log(y_))
optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost_function)
correct_prediction = tf.equal(tf.argmax(y_,1), tf.argmax(Y,1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
# train loop
cost_history = np.empty(shape=[1],dtype=float)
y_true, y_pred = None, None
with tf.Session(config = config) as sess:
sess.run(init)
for epoch in range(training_epochs):
print(' ## Epoch n°', epoch+1 )
batch = batch_generator(BATCH_SIZE, tr_features, tr_labels)
acc_total = 0.0
for cpt, (train_features_batch, train_labels_batch) in enumerate(batch):
_,cost = sess.run([optimizer,cost_function],feed_dict={X:train_features_batch,Y:train_labels_batch})
cost_history = np.append(cost_history,cost)
correct_prediction = tf.equal(tf.argmax(y_,1), tf.argmax(Y,1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
acc = accuracy.eval(feed_dict={X:train_features_batch,Y:train_labels_batch})
acc_total = (acc_total*cpt + acc)/(cpt+1)
print('Train accuracy : ', acc_total, '[',str(cpt+1), '/',str(number_loop), ']' ,flush=True, end='\r')
clear_output()
print('Train accuracy : ', acc_total)
y_pred = sess.run(tf.argmax(y_,1),feed_dict={X: ts_features})
y_true = sess.run(tf.argmax(ts_labels,1))
print('Test accuracy: ', round(sess.run(accuracy, feed_dict={X: ts_features, Y: ts_labels}) , 3))
fig = plt.figure(figsize=(10,8))
plt.plot(cost_history)
plt.axis([0,training_epochs,0,np.max(cost_history)])
plt.show()
p,r,f,s = precision_recall_fscore_support(y_true, y_pred, average='micro')
print("F-Score:", round(f,3))
def batch_generator(batch_size, feat_path, labels):
n_sample = len(feat_path)
ite = math.ceil(n_sample/batch_size)
for i in range(0, ite):
if i == ite-1:
label = one_hot_encode(labels[-batch_size:])
feat = get_specgrams(feat_path[-batch_size:])
yield (feat, label)
else:
label = one_hot_encode(labels[i*batch_size:i*batch_size+batch_size])
feat = get_specgrams(feat_path[i*batch_size:i*batch_size+batch_size])
yield (feat, label)
def get_data(feat_path, labels):
feat = get_specgrams(feat_path)
label = one_hot_encode(labels)
return feat, label
def __main__():
print('## Load data and shuffle')
feat_path, labels = prepare_data('data_labelised2.txt')
idx = int(len(labels)*0.8)
print("## Create Model")
model(feat_path[0:idx], labels[0:idx], feat_path[idx+1:], labels[idx+1:])
with tf.device('/gpu:0'):
__main__()