# Questions tagged [pattern-recognition]

Refers to techniques for classifying data into categories based on similarities (which can either be known previously, or learned).

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### Minimizing the expected loss (PRML)

In Bishop's PRML in section 1.5.2, the author introduces a loss function for classification, which is the expected loss, $$E[L]=\sum_k \sum_j \int_{R_j} L_{kj}p(\textbf{x},C_k)d\text{x}$$ where Lkj ...
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### Pattern mining: is this pattern the result of mere chance?

I have a sequence $S$ of characters generated from a finite alphabet $\Sigma$. Let's assume all characters are equally probable within $S$. I have a frequent pattern mining algorithm that, for ...
1 vote
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### Identifying groups/patterns in a random dataset using Matlab [closed]

I have the datasets which may contain multiple patterns. The data needs to be classified based on grouping in the data. The figure below shows an example of the data. The circles around the data are ...
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### Measuring entropy of a binary matrix with biased probability

I tried to measure entropy of binary matrix like below using code at : https://github.com/cosmoharrigan/matrix-entropy (I already saw the question : Measuring entropy/ information/ patterns of a 2d ...
20 views

### In a specifically ordered set of binary data (ones and zeros), how can you organize them in patterns and from there build a probabilistic network? [duplicate]

So I have a set of 1s and 0s. They are listed in a column on excel. They are listed in a specific order. I do not wish to change their order. So they appear as (1, 0, 1, 0, 0, 1 and so on... 0). Here ...
55 views

### Prove that Residuals/Errors are not Predictable [duplicate]

Let's say I have a set of data and I modelled it using an ML algorithm. After I fit multiple models I achieve a certain level of accuracy. It doesn't get better beyond that point. I want to prove ...
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### Is there any approach to find out the association between the arithmetic-combination of variables to other single variable?

I have 30 set of data (each set has been recorded from one subject) that contain of a single gold-standard measurement value (recorded by standard medical device) and another 200 numerical values that ...
1 vote
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### From the book "Bishop- Pattern Recognition and Machine Learning" Page 31 [closed]

From the book "Bishop- Pattern Recognition and Machine Learning" Page 31. Can you help me derive the equation (1.68) from equations (1.69), (1.70) and (1.71). Please explain every step for ...
1 vote
53 views

### ICA and Gaussian: a misleading example

A book reports that ICA cannot be used if the independent components of the analyzed data are Gaussian (at most one can be Gaussian, but no other). However, in the same book, the following example is ...
107 views

### Detect quoted text in emails

I have small dataset (<10k) of emails (plaintext) that need to be classified. Currently I'm doing research on topic of email preprocessing and I can't find any suitable solution for quoted text ...
1 vote
22 views

### How to create piecewise linear and quadratic classifier

Can someone suggests a literature that describe a procedure for projecting a piece-wise linear and piece-wise quadratic classifiers? For example, let's say I have these classes: How would I calculate ...
109 views

### Understanding Equation (3.13) from Bishop's Pattern Recognition and Machine Learning

I'm having trouble deriving the mentioned equation from the text. Specifically, I'm having trouble obtaining the $\mathbf{\phi}(x_n)^T$ term. I checked the errata and while the lack of the $\beta$ ...
1 vote
17 views

### Software to identify or reverse engineer patterns from encoded / decoded data

I have a CSV file that contains encoded date data. I have no idea how the data was encoded, but you can look at the data and see an obvious pattern which means it was probably some sort of custom ...
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### Distance between two clusters after their joining in centroid linkage

For a distance between two clusters A and B of objects given by $d_{AB}=\left \|{m_{A}-m_{B}} \right \|^{2}$ , where $m_{A}$ is the mean of the objects in cluster $A$, show that the formula ...
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### Identification of a pattern based on given features in time-series data

I am working with electricity time-series data collected at 15 minutes intervals. I am looking for a procedure/theory to find the pattern/sequence in the time-series data based on given features. As I ...
185 views

### Flagging bad time series behavior (Pattern Recognition and Outlier Detection)

I want to get some opinions on how to approach the following problem to do with detecting "unhealthy" behavior in time series data (either using a statistical/analytical model or ML/DL, I do ...
1 vote
32 views

### Measure how dataset is harmonious or organized

Suppose we have two set of numbers : A = [1,4,9,16,25,49...100] and B = [1,4,7,7,25,49,64...100]. As you seen the first one is consistently growing, elements of it is square of numbers. But although ...
1 vote
45 views

### What is the difference between these two types of training?

Suppose that I want to detect if a picture contains a particular logo, for instance the following one. Since template matching would be slow and fail those scaled or resized ones, I decided to train ...
1 vote
34 views

### Discover a pattern in a set of spectrograms given a real rating

I'm trying to find patterns in a sorted set of spectrograms, each with a rating. The main idea is to train the CNN in such a way that it understands how the pattern "evolves" at each step, ...
1 vote
47 views

### PCA to identify patterns in the data, forced to a particular variable?

Dataset: I have a hyperspectral dataset that consists 250 wavelength bands (x1,...x250) and corresponding reflectance measurements (y) for each band. Plotting X vs Y yields a spectral profile. I have ...
762 views

### How does addition of a regularization term ensures that the matrix is nonsingular? ( least squares )

In Bishop's Pattern recognition book, in 3.1.2 Geometry of least squares section (page 143, last paragraph of section), it is stated that: In practice, a direct solution of the normal equations can ...
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### Intuition behind random strides in CNNs

I recently attended a lecture on CNNs and was given a brief overview on the topic of dropout. I understood the logic behind the regularization and silencing the firing of neurons to prevent ...
1 vote
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### Bayesian Parameter estimation (Pattern Classification by Duda, et al

I have been trying to solve question 17 of chapter 3 (Maximum Likelihood and bayesian estimation) of the book "Pattern Classification" by Duda, et al. The question goes as follows: Now the ...
1 vote
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### Siamese Network for face comparison wont learn, accuracy stuck on 0.5, and loss stuck too [duplicate]

I'm trying to train a siamese network which contains a CNN and an embedding layer at the end to yield 2 similar (close) vectors for 2 images of the same person. I'm using the LFW_Cropped dataset, and ...
81 views

### Robustly extracting subpatterns from time-series data

As part of an experiment, I need to collect time-series samples which are tightly associated with some input data. I send this data to an external device, and then collect the associated trace using ...
1 vote
488 views

### What does the meaning of the autocorrelation in this picture?

From this figure, how should I understand what is the lag on the top figure? and when in the bottom figure for example the autocorrelation is 0.45 what does tell us about the above figure? Another ...
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### If machine learning, in general, is about ‘learning’ patterns, is it correct to say its branches differ based on the type of pattern being learnt?

If machine learning, in general, is about ‘learning’ patterns, is it correct to say its branches differ based on the type of pattern being learnt? I.e. in supervised learning the pattern is a target ...
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### How to extract simple shapes from a feature map?

I am working on image parsing project. I want to find a way to automatically parse an object into a list or a graph of simpler shapes. Is there any practical information on how to do so? So far I took ...
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### Cluster analysis with interchangeable, binary classes

The Data: I have the results of an experiment where participants were given 30 stimuli and asked to sort them into two groups. The participants were asked to sort them into the two groups without any ...
1 vote
53 views

### Avoiding overfitting in unsupervised ML

I am using a unsupervised pattern matching approach to create a trade strategy. I use the output of the pattern matched results to decide whether to enter a trade or not. For deciding the best pattern ...
1 vote
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### Techniques for finding patterns in binary data

I have a question about data analysis and I am wondering if someone can advise? I am interested in what mathematical techniques are available to look for patterns in binary data. Say I have a black ...
1 vote
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### Comparing probabilites of error for differenct 'k' in a k-NN Classifier

Here is a question that I'm stuck with: Consider two classes $w_1$, $w_2$ in the two-dimensional space. The data from class $w_1$ are uniformly distributed inside a circle of radius $r$. The data of ...
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### Explain equation 1.80 in Pattern Recognition and Machine Learning, Bishop

$$E[L] = \sum_k \sum_j \int_{R_j} L_{k,j} p(x, C_k)$$ L is a loss function that returns a real value given a pair (i,j), with i as the index of true class, and j as the index of the predicted class of ...
1 vote
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### Viewing a kernel as a probability density: Why are we only integrating with respect to $x$ and not $x^\prime$?

I am currently studying the textbook Learning with kernels: support vector machines, regularization, optimization and beyond by Schölkopf and Smola. Chapter 1.2 A Simple Pattern Recognition Algorithm ...
1 vote
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### Q-function in Q-Learning

I ran into solved old-exam question as follows: My notes tell me that option b is correct but I think option d is correct. is there any idea why (b) is correct? 458 views

### Information gain of the root node

Recently I saw this question and answer as attached in following image Anyone can add details how this solution achieved?
1 vote
277 views

### taylor series expansion in laplace approximation of bayesian neural network prediction

In chapter 6 of the book Pattern recognition and machine learning, there is this part about prediction in Bayesian neural network using laplace approximation : why assuming small variance compared ...
1 vote
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### Chernoff bound for bayes classifier

It's mentioned in many pattern recognition textbooks (Duda, Theodoridis,etc) that Chernoff distance is: but I couldn't find the proof and I wasn't able to derive it myself. Some insight on the ...
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### Why might the functional form of a distribution be "inappropriate" for a particular application?

Working through Bishop's Pattern Recognition and Machine Learning(a great read so far!) and on page 67 he says: "One limitation of the parametric approach is that it assumes a specific ...
794 views

### Why maximizing the expected value of log likelihood under the posterior distribution of latent variables maximize the observed data log-likelihood?

I am trying to understand the Expectation-Maximization algorithm and I am not able to get the intuition of a particular step. I am able to verify the mathematical derivation but I want to understand ...
1 vote
522 views

### Euclidian distance vs cosine similarity

Currently I'm working on facial recognition. If I use encoding/feature vectors of 2 images which method will prove more accuracy, L2 norm or cosine similarity and why? I read "ICA performs ...
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### How can you use a neural network to extract the needed information from social media ads?

How to solve the following problem using neural networks / and machine learning / artificial intelligence? Input data - is an ad from a channel or group of a social network. For example, this: A room ...
1 vote
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### Question about package 'dtw' in R [closed]

Please see below images. Using package 'dtw' in R, is there a way to ensure that pattern 1) has a lower computed distance relative to the reference pattern than pattern 2) does. In other words, can ...
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### Analysis to view patterns or correlations between multiple variables

I have a dataset with many variables (yes/no) questions from a questionnaire on different symptoms experienced (yes I have symptom/no I don't have symptom) with thousands of participants. As an ...
1 vote