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Questions tagged [algorithms]

An unambiguous list of computational steps involved in finding a solution to a class of problems.

2
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1answer
359 views

Procedure of PRESS statistic

It is not very clear for me the calculation steps of PRESS statistic. What I have found: 1)we set aside the $j_{th}$ observation $⟨x_j,y_j⟩$ from the training set(It means, that we just remove the ...
4
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1answer
2k views

Understanding NIPALS algorithm for PLS

I've found a nice presentation describing PLS1 and PLS2 algorithms (pages 16-19). It's pretty clear but there is a thing confusing me. For PLS1. Let's look at the algorithm. The first steps are $w = ...
0
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1answer
153 views

How to use Naive Bayes with “not found” label?

I'm trying to do text detection thanks to Naive Bayes Algorithm. If I teach my tool: "Football is a great hobby" and assign it to the label "football", I'm totally fine with it detecting "I play ...
3
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1answer
181 views

Method of alternating projections for linear fixed effects models

The standard fixed effects model (in econometrics, mostly) is $$ y = \mathbf{X\beta} + \mathbf{D\alpha} + \epsilon $$ where $\mathbf{D}$ is a set of factors, potentially with thousands of levels. ...
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0answers
65 views

Algorithm for neuron activation order

I'm developing a JS library with the ability to create 'flexible' neural networks. Flexible meaning that they don't consist of layers, but merely of single neurons or neuron 'groups'. I don't want ...
3
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1answer
83 views

Beginner trying to improve text classification

I'm a beginner in machine learning. Basically, I'm starting from the very beginning. My problem I have 100 text documents, with 200 pages. I would like to be able to detect topics in these ...
1
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1answer
1k views

Using only one mic in Cocktail Party Algorithm

So I came across this piece of code that separates 2 audio sources from 2 mixed audio sources has shown here: ...
3
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1answer
89 views

How to extend Solomonoff's universal prior to stochastic models?

Solomonoff's universal prior for models is based on the algorithmic complexity of a computer program $p$ which executes that model. Where $l$ is the length of the computer program, the prior is ...
4
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0answers
144 views

What is the fastest way to compute PC1 scores, without performing the whole PCA?

I want to compute only the first principal component's scores $t_1$ of a large number $n$ of data points x with a high dimensionality $p$. Assume the data has been centered about zero. Data points ...
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0answers
1k views

How to properly calculate the cross-correlation?

I'm writing a simple C program that calculates the cross-correlation between two data sets. Although I've done a good search on how the calculation should be performed, I couldn't figure out some ...
2
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1answer
138 views

How can I rate the question according to the difficulty?

I have a set of problems to analyze from a programming contest. My work is to rate the question according to its difficulty (easy,medium,hard) by analyzing the ...
1
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0answers
113 views

Find a subset of input data space with high classification accuracy?

I'm having what would seem to be quite a general and widely applicable problem but I can't find literature on the subject. Example problem: Imagine I have medical records of thousands of patients (...
0
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1answer
39 views

What kind of algorithm can perfom classification / regression on numerically ordered and bucketized values

I have a dataset which is labelled with bucketized numerical values. (0-2, 3-8 ... for example). I can transform these values into their centroid and perform a regression but I think the best would ...
4
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3answers
355 views

Sampling from categorical distribution when the sorting step is ignored

The commonly used algorithm to sample from categorical distribution is sort the vector of cumulative probabilities $\boldsymbol{p} = (p_1,p_2,\dots,p_n)$ in decreasing order from the categories ...
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0answers
73 views

How to calculate higher-order network statistics given a probablistic, directed adjacency matrix

I've got a directed, probabilistic graph (network). See the picture below for a super-simple example: The adjacency matrix $\mathbf{A}$ has values between zero and one, and it isn't a symmetric ...
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0answers
164 views

Inconsistent ridge regression coefficient estimates returned by lm.ridge

I'm using lm.ridge from the library MASS and am getting (I think) nonsense when I extract the coef attribute of the fitted model. This may be because I'm ...
2
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2answers
466 views

Is Glove a prediction-based model?

I read "Improving Distributional Similarity with Lessons Learned from Word Embeddings" and authors mentioned that Glove is a prediction-based model while it is clearly factorizing co-occorrence matrix ...
1
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1answer
154 views

Are loss functions what define the identity of each supervised machine learning algorithm?

For supervised machine learning algorithms (ie: regularized logistic regression, SVM, decision trees, etc), are their specific loss functions the main/only reason they differ from one another?
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0answers
506 views

Predict stock market using twitter

I'm trying to predict the daily positivity or negativity of stock market value through Twitter. I researched a lot about this topic and I found this article to start. Basically, what I've done is get ...
2
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1answer
82 views

How to sample so that there is equal inclusion probability for each member of the population?

Suppose we have a population where $a$ boys below 15 years are white, $b$ boys above 15 years are white, $c$ boys below 15 years are black and $d$ boys above 15 years are black. Describe a way to ...
3
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1answer
952 views

Parallel minibatch gradient descent algorithms

I've implemented a neural network using batch gradient descent. Now I want to try minibatch, largely in order to avoid problems with local minima. In ESL's chapter on neural networks, the authors ...
0
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1answer
292 views

Find circle coordinates with points by machine learning

I have 5 planes that are parallel to each other. Some circles collisions with the planes and i have 5 collision points for each circle. Now how i find the coordinates of each circle with that points ...
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0answers
54 views

detect communitites in evolving networks

My goal is to detect communities in a network tha evolve over time. I am using graph snapshots of a dataset.I want to represent the network as a step of timestep graphs, so the problem then becomes a ...
4
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2answers
7k views

Tic Tac Toe AI with Machine Learning

I am new to machine learning and as one of my first projects I decided to make a tic tac toe bot. What I've done so far is a rgb/hex color recognition with the naive bayes algorithm, which was really ...
2
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1answer
481 views

How can I filter out GPS “spidering” from tracks created when user is stationary?

We collect vehicle mileage data from GPS loggers (based on a 5 second sample of location) and need an accurate measure of the mileage travelled. However what's caught us out is that some vehicles ...
1
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3answers
2k views

Optimization vs Brute-force. What is the difference?

Question I've recently discovered that a brute-force algorithm is much faster at solving an optimal solution than the optimization routine for a particular problem I've been working on. This is ...
2
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1answer
207 views

What algorithm does SPSS Modeler use for decision-lists

I am currently trying to find out what algorithm IBM SPSS Modeler is using during calculation of decision lists. However, on the help page I can only find options for using the decision-list function ...
4
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0answers
144 views

Optimization by random sampling

Around the internet, I have seen scattered references to the idea of rescaling an objective function and using that as a PDF for the purpose of optimization. (On this site for example: Do optimization ...
2
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1answer
158 views

Gaussian mixture distribution confusion

Have some confusion on Gaussian mixture distribution model (reference is from the book of Pattern Recognition and Machine Learning). My confusion is how below formula works? $\sum_kz_k=1$ My thought ...
1
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0answers
130 views

What are the computational complexities of Linear One-vs-One, Bayesian Multivariate, and k-NN algorithms?

What are the computational complexities of Linear One-vs-One Committe, Bayesian multivariate with the class independence assumption, and k-NN algorithm with k=3? In $\mathcal{O}$ (Big-O) notation?...
5
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2answers
190 views

Comparing two classifiers from a binary response

$\newcommand{\P}{\mathbb{P}}$$\newcommand{\rank}{\operatorname{rank}}$I have a testing dataset with a binary response (0, 1) and two algorithms each estimating the probability of 1 for each trial. I ...
3
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0answers
38 views

Algorithmic Complexity of Estimators

I am interested in evaluating the algorithmic complexity of an estimator of the form: $$\hat{\theta} = \text{argmin}_{\theta} \;\; Q_n (\theta)$$ where $Q_n(\theta)$ denotes some objective function ...
1
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3answers
678 views

Algorithm to identify similar frames in a video

Looking at the frames of a video, we can see that many frames are almost identical. Is there any algorithm to identify these frames, so I can delete them all but one?
0
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1answer
453 views

Determine correct statistical algorithm for mixed-type data

I have a dataset consisting of ~20000 lines and 8 columns. It is a mixture of binary and float data, but one binary variable is the important one and I want to create a model to predict the other ...
0
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1answer
26 views

Metric for determining how different a given string is from elements in a larger body of text?

I am trying to remove names from a large body of text to reduce the noise in my dataset. I have tried several approaches: Python's nltk.pos_tag function and a more ...
0
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2answers
440 views

K-mean++ initialization algorithm alternative

I got this question as an exercise, and I frankly don't know where to begin: Consider the deterministic variant of the k−means++ algorithm where the set of initial centroids are selected in the ...
1
vote
1answer
117 views

Efficiently computing poisson binomial sum

Suppose there is a match between two teams where the first team to win a certain number of games wins the match. The match is handicapped, with Teams A needing to win $H_A$ games and Team B needing $...
2
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0answers
62 views

Which approach and statistical hypothesis test should I choose when testing performance results of many algorithms?

I have 4 algorithms which are doing the same thing in different ways. Let's name them A,B,C,D. I assume that one of them may have better results than others. I'd like to confirm this by test. I'm ...
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1answer
198 views

How can one estimate compute requirements for Machine Learning algorithms?

Has anyone developed formulas or rules of thumb for estimating CPU, memory and time requirements for running various Machine Learning algorithms (or families of algorithms), with respect to training ...
1
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1answer
2k views

Are there algorithms and tools that can optimize black box functions with black box constraints?

Suppose that we have an objective function f which have as parameters x1,x2. f is an objective function to be maximized for a given problem.Lets say: f(x1,x2)=x1+x2+E(x1,x2) where E is a neural ...
3
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1answer
126 views

Is it good practice to perform model parameter tuning on a random subsampling of a large dataset?

A lot of the datasets presented to us in the company at which I'm currently an intern are very large (many millions of rows / Gigabytes, or even Terabytes of data). While running machine learning ...
5
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1answer
1k views

Belief propagation using pgmpy lib - algorithm understanding

I am now starting to use pgmpy lib for probabailistic graphical model implementation. The probability that I get using this lib differs from the one I get manually (e.g. using SamIam). Here is a ...
3
votes
1answer
460 views

Successive odds of a high or low card on Play your cards right(Card Sharks)

I am looking for a way to calculate the high or low odds for each card turn in a game of "Play your cards right". You can play this game and see what I mean here Basically, there are several rows of ...
1
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1answer
100 views

Bootstrapping prior to running classification learner app in Matlab

I am trying to utilize the classification learner app in Matlab for a set of data for cancerous and noncancerous cells (6 different types of cells). Would bootstrapping the data prior to feeding the ...
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0answers
93 views

Methodology for comparing a deterministic and stochastic regression algorithm

I am trying to compare two different algorithms for performing regression. One of the algorithms (call it A) is deterministic, i.e. given the same training data and test data it will always produce ...
0
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0answers
174 views

Machine Learning Algorithm to make predictions on 3D graphs

So, I have a lot of 3D Plot data that are either in the A category or B category. A short truncated sample of one of the data files is this: ...
1
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2answers
194 views

Sampling from discrete distribution - running time of accept reject

I have a question about the running time of the accept/reject method to sample from discrete distributions. I'm sampling from two distributions built like this: draw $n_{outcomes}$ number from an ...
1
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1answer
58 views

Robustness of neural net in datapoints reordering

Has anybody tested how robust a neural network is on random reorderings of the training set? Training a neural net with identical hyperparameters on the same training dataset with random permutations ...
5
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1answer
989 views

Complexity of a random forest with respect to maximum depth

I expect the training time of a random forest to be : linear in the number of trees (obviously), linear (or square-root) in the number of columns (depending on the choice for the subsampling of the ...
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0answers
37 views

Iterative Optimization of Likelihood Function

If we have 3 input vectors $\boldsymbol{y}_{1},\boldsymbol{y}_{2},\boldsymbol{y}_{3}$ let $\mathbf{y}=[\boldsymbol{y}_{1},\boldsymbol{y}_{2},\boldsymbol{y}_{3}]$. Based on this, I want to model $\...