Questions tagged [deep-learning]

a new area of Machine Learning research concerned with the technologies used for learning hierarchical representations of data, mainly done with deep neural networks (i.e. networks with two or more hidden layers), but also with some sort of Probabilistic Graphical Models.

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How to set the number of neurons and layers in neural networks

I am a beginner to neural networks and have had trouble grasping two concepts: How does one decide the number of middle layers a given neural network have? 1 vs. 10 or whatever. How does one decide ...
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248 votes
10 answers
360k views

How to set class weights for imbalanced classes in Keras?

I know that there is a possibility in Keras with the class_weights parameter dictionary at fitting, but I couldn't find any example. Would somebody so kind to ...
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42 votes
5 answers
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Does gradient descent always converge to an optimum?

I am wondering whether there is any scenario in which gradient descent does not converge to a minimum. I am aware that gradient descent is not always guaranteed to converge to a global optimum. I am ...
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33 votes
6 answers
14k views

Why do convolutional neural networks work?

I have often heard people saying that why convolutional neural networks are still poorly understood. Is it known why convolutional neural networks always end up learning increasingly sophisticated ...
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180 votes
5 answers
127k views

What is the "dying ReLU" problem in neural networks?

Referring to the Stanford course notes on Convolutional Neural Networks for Visual Recognition, a paragraph says: "Unfortunately, ReLU units can be fragile during training and can "die". For ...
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66 votes
5 answers
44k views

Adding Features To Time Series Model LSTM

have been reading up a bit on LSTM's and their use for time series and its been interesting but difficult at the same time. One thing I have had difficulties with understanding is the approach to ...
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64 votes
4 answers
69k views

Why mini batch size is better than one single "batch" with all training data?

I often read that in case of Deep Learning models the usual practice is to apply mini batches (generally a small one, 32/64) over several training epochs. I cannot really fathom the reason behind this....
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37 votes
2 answers
53k views

Should we apply normalization to test data as well?

I am doing a project on an author identification problem. I applied the tf-idf normalization to train data and then trained an SVM on that data. Now when using the classifier, should I normalize test ...
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58 votes
10 answers
80k views

Why should the data be shuffled for machine learning tasks

In machine learning tasks it is common to shuffle data and normalize it. The purpose of normalization is clear (for having same range of feature values). But, after struggling a lot, I did not find ...
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72 votes
4 answers
34k views

What is the difference between "equivariant to translation" and "invariant to translation"

I'm having trouble understanding the difference between equivariant to translation and invariant to translation. In the book Deep Learning. MIT Press, 2016 (I. Goodfellow, A. Courville, and Y. Bengio)...
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  • 883
57 votes
5 answers
69k views

Number of parameters in an LSTM model

How many parameters does a single stacked LSTM have? The number of parameters imposes a lower bound on the number of training examples required and also influences the training time. Hence knowing the ...
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  • 1,237
22 votes
2 answers
35k views

Why ReLU is better than the other activation functions

Here the answer refers to vanishing and exploding gradients that has been in sigmoid-like activation functions but, I guess, Relu...
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155 votes
19 answers
184k views

How do you visualize neural network architectures?

When writing a paper / making a presentation about a topic which is about neural networks, one usually visualizes the networks architecture. What are good / simple ways to visualize common ...
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29 votes
7 answers
16k views

Can machine learning learn a function like finding maximum from a list?

I have an input which is a list and the output is the maximum of the elements of the input-list. Can machine learning learn such a function which always selects the maximum of the input-elements ...
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  • 299
30 votes
4 answers
30k views

What is the relationship between the accuracy and the loss in deep learning?

I have created three different models using deep learning for multi-class classification and each model gave me a different accuracy and loss value. The results of the testing model as the following: ...
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  • 1,755
12 votes
1 answer
4k views

Using a pre trained CNN classifier and apply it on a different image dataset

How would you optimize a pre-trained neural network to apply it to a separate problem? Would you just add more layers to the pre-trained model and test it on your ...
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  • 617
11 votes
1 answer
19k views

Keras LSTM with 1D time series

I'm learning how to use Keras and I've had reasonable success with my labelled dataset using the examples on Chollet's Deep Learning for Python. The data set is ~1000 Time Series with length 3125 with ...
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6 votes
2 answers
7k views

What are useful evaluation metrics used in machine learning

I am using CNN in order to predict codes after analyzing text. As an example, I will write "I am crazy" .. the model will predict some code " X321". All this based on CNN. I want to evaluate my ...
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  • 215
8 votes
1 answer
17k views

Why should softmax be used in CNN

In the last layer of CNNs and MLPs it is common to use softmax layer or units with sigmoid activation functions for multi-class ...
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5 votes
1 answer
5k views

How can I add custom numerical features for training to BERT fine tuning?

I have currently fine tuned the BERT model on some custom data and I want to conduct some more experiments to increase the accuracy. My original dataset consists of a pair of sentences (like MRPC ...
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69 votes
6 answers
138k views

Cross-entropy loss explanation

Suppose I build a neural network for classification. The last layer is a dense layer with Softmax activation. I have five different classes to classify. Suppose for a single training example, the <...
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  • 2,921
28 votes
6 answers
10k views

Deep learning basics

I am looking for a paper detailing the very basics of deep learning. Ideally like the Andrew Ng course for deep learning. Do you know where I can find this ?
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81 votes
1 answer
79k views

When to use (He or Glorot) normal initialization over uniform init? And what are its effects with Batch Normalization?

I knew that Residual Network (ResNet) made He normal initialization popular. In ResNet, He normal initialization is used , while the first layer uses He uniform initialization. I've looked through ...
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41 votes
4 answers
27k views

Why is ReLU used as an activation function?

Activation functions are used to introduce non-linearities in the linear output of the type w * x + b in a neural network. Which I am able to understand ...
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20 votes
2 answers
12k views

Difference between LSTM cell state and hidden state

LSTM cells consist of two types of states, the cell state and hidden state. How do cell and hidden states differ, in terms of their functionality? What information do they carry?
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24 votes
2 answers
9k views

local minima vs saddle points in deep learning

I heard Andrew Ng (in a video I unfortunately can't find anymore) talk about how the understanding of local minima in deep learning problems has changed in the sense that they are now regarded as less ...
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  • 5,995
8 votes
1 answer
38k views

How to download dynamic files created during work on Google Colab?

I have two different files and on the first, I tried to save data to file as: np.save(open(Q1_TRAINING_DATA_FILE, 'wb'), q1_data) On second file, i'm trying to ...
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  • 185
10 votes
5 answers
14k views

In which epoch should i stop the training to avoid overfitting

I'm working on an age estimation project trying to classify a given face in a predefined age range. For that purpose I'm training a deep NN using the keras library. The accuracy for the training and ...
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20 votes
3 answers
20k views

Should I use GPU or CPU for inference?

I'm running a deep learning neural network that has been trained by a GPU. I now want to deploy this to multiple hosts for inference. The question is what are the conditions to decide whether I should ...
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  • 311
15 votes
1 answer
19k views

What is a 1D Convolutional Layer in Deep Learning?

I have a good general understanding of the role and mechanism of convolutional layers in Deep Learning for image processing in case of 2D or 3D implementations - they "simply" try to catch 2D patterns ...
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8 votes
2 answers
12k views

How to plot cost versus number of iterations in scikit learn?

One of the recommendations in the Coursera Machine Learning course when working with gradient descent based algorithms is: Debugging gradient descent. Make a plot with number of iterations on the x-...
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2 votes
1 answer
472 views

Compute backpropagation

I have the question which is mentioned in the above picture. It is trying to find the derivative of f with respect to weight matrix ...
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  • 521
2 votes
2 answers
2k views

Explain Binary Classification with output 0.5 (True)

What is the interpretation of output 0.5 of a typical classifier? I made a prediction and the probability of that data point being from the True class is 0.5.
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178 votes
6 answers
290k views

How to draw Deep learning network architecture diagrams?

I have built my model. Now I want to draw the network architecture diagram for my research paper. Example is shown below:
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  • 2,277
85 votes
7 answers
60k views

Time series prediction using ARIMA vs LSTM

The problem that I am dealing with is predicting time series values. I am looking at one time series at a time and based on for example 15% of the input data, I would like to predict its future values....
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  • 1,065
59 votes
4 answers
75k views

Does batch_size in Keras have any effects in results' quality?

I am about to train a big LSTM network with 2-3 million articles and am struggling with Memory Errors (I use AWS EC2 g2x2large). I found out that one solution is to reduce the ...
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  • 1,110
43 votes
2 answers
69k views

Merging two different models in Keras

I am trying to merge two Keras models into a single model and I am unable to accomplish this. For example in the attached Figure, I would like to fetch the middle layer $A2$ of dimension 8, and use ...
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  • 973
27 votes
3 answers
2k views

Why are NLP and Machine Learning communities interested in deep learning?

I hope you can help me, as I have some questions on this topic. I'm new in the field of deep learning, and while I did some tutorials, I can't relate or distinguish concepts from one another.
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37 votes
1 answer
56k views

How does Keras calculate accuracy?

How does Keras calculate accuracy from the classwise probabilities? Say, for example we have 100 samples in the test set which can belong to one of two classes. We also have a list of the classwise ...
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  • 1,002
17 votes
4 answers
43k views

Question about bias in Convolutional Networks

I am trying to figure out how many weights and biases are needed for CNN. Say I have a (3, 32, 32)-image and want to apply a (32, 5, 5)-filter. For each feature map I have 5x5 weights, so I should ...
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  • 1,881
9 votes
2 answers
16k views

Using Cross Validation technique for a CNN model

I am working on a CNN model. As always, I used batches with epochs to train my model. When it completed training and validation, finally I used a test set to measure the model performance and generate ...
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  • 1,067
26 votes
2 answers
16k views

Is there away to change the metric used by the Early Stopping callback in Keras?

When using the early stopping callback in Keras, training stops when some metric (usually validation loss) is not increasing. Is there a way to use another metric (like precision, recall, or f-measure)...
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  • 373
15 votes
5 answers
6k views

Why does adding a dropout layer improve deep/machine learning performance, given that dropout suppresses some neurons from the model?

If removing some neurons results in a better performing model, why not use a simpler neural network with fewer layers and fewer neurons in the first place? Why build a bigger, more complicated model ...
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  • 1,195
12 votes
2 answers
19k views

Activation function between LSTM layers

I'm aware the LSTM cell uses both sigmoid and tanh activation functions internally, however when creating a stacked LSTM architecture does it make sense to pass their outputs through an activation ...
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  • 232
11 votes
2 answers
1k views

When do we say that the dataset is not classifiable?

I have many times analysed a dataset on which I could not really do any sort of classification. To see whether I can get a classifier I have usually used the following steps: Generate box plots of ...
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  • 178
9 votes
5 answers
5k views

How does deep learning helps in detecting multiple objects in single image?

Let's say there are two cars in an image. How can it detect these cars, given that it can detect single car in an image?
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6 votes
2 answers
3k views

How to sort numbers using Convolutional Neural Network?

Recently, in an interview I got this question: Design a convnet that sorts numbers. Operators are ReLU, Conv, and Pooling. E.g. input: 5, 3, 6, 2; output: 2, 3, 5, 6 I am not sure how can you sort a ...
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12 votes
1 answer
7k views

Reason for square images in deep learning

Most of the advanced deep learning models like VGG, ResNet, etc. require square images as input, usually with a pixel size of $224x224$. Is there a reason why the input has to be of equal shape, or ...
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  • 563
5 votes
2 answers
5k views

RNN time-series predictions with multiple features containing non-numeric features and numeric features?

The question RNN's with multiple features is ambiguous and not explicitly in differentiating different features. I want to understand how to use RNN to predict time-series with multiple features ...
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  • 171
4 votes
1 answer
208 views

Fake News Detection problem

I would like to work on a project for Fake News Detection especially for Indians news which are in different languages and different formats. Fake news as image with no or very less text Fake news on ...
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