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Questions tagged [algorithms]

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

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Tree pruning & cost-complexity

This is a question in cost complexity pruning that I want to learn about. I am given $A ≥ 0$ to be the tuning parameter, where $t_0$ is the full tree, and $t$ is a subtree. We then have $|t|$ as ...
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12 views

Grouping Similar Sequences

I have extracted a ton of log data from a mobile application. The objective of this task is to identify similar patterns of behavior. Which algorithm should I look at which will group behaviors ...
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1answer
131 views

Time complexity of simple linear regression in $L_1$ norm

I come from a computer science background. I'm considering simple linear regression using $L_1$ distance. We are given points $(x_1,y_1),\ldots,(x_n,y_n)\in \mathbb{R}^2$. We are interested in ...
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31 views

Question about validity of an MCMC algorithm

Let suppose I want to sample from the posterior distribution of $X_1,X_2|y$ using an MCMC algorithm and let indicate with $X_i^t$ the value of $X_j$ at the $t-$th iterations. I want to know if the ...
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1answer
50 views

Probability that rolling N dice that the two larger dice sum to X [closed]

New here. I'm trying to figure out how to come up with a roll system for a game, where i want the probability of rolling N dice or rolling one dice N times and then taking the two largest outcomes, ...
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21 views

Iteratively Reweighted Least Squares Poisson Regression with Non-Canonical Link, eventually in R

I am attempting to implement iteratively reweighted least squares (IRLS) for a poisson regression with a non-canonical link function. My understanding of IRLS is only basic at this point, so please ...
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0answers
12 views

Create score for comaparison of algorithms

The following graph gives the results from a test. The y axis shows the MAPE (error) which should be minimum, the x-axis shows the epochs which should also be minimum. As one can see two algos are ...
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21 views

What is the purpose of using a decision tree? [duplicate]

I don't understand what is the purpose of the decision tree? The way I see it is, it is a series of if-else. Why don't I just use if-else instead of using a decision tree? It is because it decreases ...
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1answer
54 views

Why is there a loop in the ROC curve? [closed]

I am trying to implement a multi-criteria classifier algorithm. It uses 6 criteria that output 1 or 0 if a specific signal is detected in the input data or not. Then it computes a weighted average of ...
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25 views

Cardinality estimation using ordered statistics

In cardinality problem (count-distinct problem) the goal is to estimate the number of unique elements in a set. HyperLogLog is one such algorithm [ref] Another approach is using order statistics, such ...
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2answers
26 views

Looking for clues on a possible method or approach for clustering particle data in the form of pulse shapes

I'm a biologist by origin, and I'm asking this question to the math community to learn from the vast knowledge that I don't posses myself but is out there in the math field. Edit: This question was ...
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0answers
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Partial Least Squares Regression : deflation of the Y matrix

I am digging deep into the PLSR algorithms and while I have found multiple flavours of if (different normalisations, SIMPLS,..), there is always something in the Y deflation that is throwing me off ...
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25 views

Are there any generally simple examples on Tabu Search in R?

I am looking for any examples of implementing Tabu Search in R. I know there is a package, but I would like to see if there are any good instructive examples where the code is built up and used to ...
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9 views

'Shrink' Step occuring often in Nelder Mead optimization?

I have an implementation of Nelder Mead, which is giving me good results. I had a bug, though, and while I managed to fix that bug, I noticed during my debugging that the 'shrink' step is occurring ...
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0answers
15 views

Clearness Scoring Function

Hello to the community, I would love to hear your opinion about a Prediction Model I am currently working on for my thesis, in order to predict the Clearness of a website. I created a dataset of 5....
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0answers
16 views

Area interaction model sufficient statistics calculation algorithm

I'm currently trying to write a simulation algorithm in Rcpp for a point process model which requires calculating the sufficient statistics for an Area interaction point process model. It entails a ...
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0answers
13 views

Which Algorithm(s) to apply for in-game behavioural data (choice-based-game)

In the near future, I'm going to analyse in-game and log data. The main purpose is to make predictions about which choices people are going to make in the future when playing this game. As log-data ...
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1answer
62 views

Algorithm for modified knapsack problem

We have n-players in a game. We have a population of players we can choose from. Each player score is a normally distributed random variable and each player has a cost to add to the team. We are ...
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22 views

Product Packaging Problem: Measuring by pieces vs. Measuring by grams

I am helping a friend with his chicharon (pork cracklings) business. Initially, each selling package contains 50 grams of the product but he changed his mind and wanted 20 pieces instead for each ...
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1answer
35 views

What's this class of algorithms called: (entire training dataset, new input) -> output?

Supervised machine learning algorithms normally work by preprocessing a training dataset and outputting a compact model (e.g. a bunch of regression coefficients) that can quickly give an approximate ...
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0answers
26 views

Statistically determining the median of a data set via quantiles of a sample

I was thinking of algorithms for statistically determining the median of a large data set. To estimate the complexity of my idea I need the following Probability: I have a dataset $\left\{x_i \right\}...
3
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1answer
67 views

why has author divided by 1.5 in hands on machine learning with scikit learn

I am reading Hands-On Machine Learning with Scikit-Learn and TensorFlow (76/718), and the author is talking about dividing the dataset into a test set which i follow, but then goes on to talk about ...
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1answer
18 views

ML Sampling question - Can I increase sample size of current dataset with older copies that have changed over time [closed]

I am working on a multinomial machine learning algorithm that labels stocks with buy/sell signals. My code updates with the most recent quantitative data about the stocks daily, so obviously the data ...
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0answers
17 views

Weighted score algorithm

I'm trying to come up with the solution for a recurrent problem in many different industries. I have an idea of what can be done, but I'm struggling to model mathematically. Here's an example: ...
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2answers
146 views

What is the difference between deep and shallow machine learning?

There's a lot of information about deep learning but what features should an algorithm have for it to be classified as deep or shallow? Is shallow only related to neural networks?
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35 views

Predict Data Using Similar Dataset (Machine Learning Algorithm)

I have a dataset of temporary streamflow monitoring data, with flows recorded every 5 minutes for a period of several months to a few years for several hundred streams across the country. I also have ...
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1answer
17 views

Prior/degree of belief/degree of lack-of-information/algorithms/complexity

For a long time I had a bit of difficulty understanding what "degree of belief" means. Recently I had some thoughts about it and I wonder if they make any sense, or is there some literature about ...
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15 views

Can we mix the algorithm?

The question comes from when I was wondering about the cross-validation, finding out the best algorithm. Then I got the question like if this model did a better job than the other, can the ...
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0answers
14 views

Algorithms for combining Bayesian networks? [closed]

Are there any algorithms for combining multiple Bayesian networks? For example, let's say I have 5 variables A, B, C, D and E, and I build 5 Bayesian networks on different random subsets of these, let'...
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0answers
11 views

Stacking Algorithms - Should Certain Algorithms Not Be Used In Conjunction

Are there any reasons why one wouldn't want to use certain algorithms together in stacking? For example, if I decided to use an SVM and a LogisticRegression classifier and were considering adding a ...
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0answers
17 views

How does Kamada & Kawai Force Directed layout algorithm interpret negative edge weights?

In Cytoscape, the Kamada & Kawai Force Directed layout algorithm is able to take negative weights between edges. Does anyone know how it's actually using the sign of these? Is it forcing ...
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0answers
5 views

Which algorithm(s) to use for quote price recommendations based on win/loss percentages by x date range?

I have a problem I'm trying to solve and was hoping someone smarter and more experienced may be able to help me out. Let me describe the problem. Thanks for any help in advance. My company provides ...
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1answer
212 views

Multi-class Decision Forest vs Multi-class Decision Jungle

guys. I have been learning about machine learning using Azure ML service from Microsoft and my team and I have seen that there are some multi-class decision algorithms, the Forest and Jungle are ...
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7 views

Ordered aggregated choices given users preferences

I have an issue creating an ordered list by preferences. Let's say I have 3 users (u1, u2, u3) and 10 topics (t1,...,t10). Each ...
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0answers
32 views

Cross - entropy for two variables with different prob. distributions

Let us say that we have given two random variables with different prob. distributions: A = [0.1, 0, 0.5, ...] B = [0.3, 0.1, 0.03, ...] What should I do when I want to compute the reformulated cross-...
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1answer
27 views

For a specific dataset do all the features have the same importance across different algorithms?

I wonder if by implementing a feature selection technic using training with a specific algorithm you can select the feature you need to use with other algorithms also. To be more specific after I ...
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2answers
68 views

Deep Neural Network visualization on multi dimension datasets [closed]

I have seen the PlayGround of Tensorflow. But it is using only 2D values which means only 2 inputs are taken. I have 7 inputs and the output is only 1. See the datasets sample: ...
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22 views

Epsilon from Bivariate Normal Distribution [duplicate]

I came across the following example from a book. I am given a dataset generated from a bivariate normal distribution: Among the data, there are missing values for the last 20 of x2i (but not for x1i)....
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30 views

Computing Wassertein Distance

For two probability measures $\mu$ and $\nu$, the Wassertein Distance is defined as $$W_p (\mu , \nu) = \left[ \inf\limits_{\gamma \in \Gamma} |x-y|^p \, d\gamma (x,y) \right] ^{\frac{1}{p}} \, , $$ ...
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24 views

Question about PyTorch tutorial

In this PyTorch tutorial the backprop to compute gradients is shown with the following code: ...
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1answer
62 views

Questions about a k-means variant : recompute centroids after each point is reasigned

I have a variant of k-means, where the points are reassigned incrementally and I have a few questions about it. Each time we reassign a point (we move the point from cluster $C_1 $to $C_2$), we ...
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2answers
72 views

Machine learning algorithm test/evaluation sample size

I have recently implemented a machine learning algorithm as a part of a new credit risk scoring system. I would now like to evaluate the accuracy/performance of the algorithm when used in a "real ...
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1answer
58 views

Comparing two algorithms. Paired t-test, independent test or mixed effect linear regression

I have two algorithms running on 100 benchmark instances. I want to test if there are significant differences in their mean average error. A significant part of those two algorithms is not ...
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1answer
27 views

prerequisites to algorithms and then to python and Machine Learning

I spent the last 5 months studying full-stack web development using the MERN stack, that is (MongoDB, Express, React and NodeJs). Now that I have seen the full picture of what I would be doing ...
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1answer
28 views

How to quickly apply an algorithm with enough understanding

Let me take an explicit example.(the answer should be universal for any algorithm) I want to group cities with similar average income together I want to use dbscan to do this.(R/python/javascript/...
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1answer
34 views

DECISION TREE : How to calculated for repeat decision noded such as this picture (C5.0 Algorithm -Decision tree)

I confused about decision tree such as this picture why repeat decision node.Could you please explain that decision tree. thank you
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1answer
33 views

Comparing Supervised ML algorithms in R on same data set

I've recently embarked on my data science journey, and I've therefore also started a data science course. In this course, we've received an assignment asking us to model a data set using different ...
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1answer
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Detecting a series of measurements

This is somewhat nonstandard: My input is a series of values (integers or reals), and my goal is to decide if this series is likely to be a series of measurements of some unknown phenomenon (be it an ...
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0answers
29 views

ranking metric for a specific use case

I am trying to find the best "ranking metric" for my problem but could not find any existing suitable metric, can someone help. I'm interested in information retrieval. For item there is a "...
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1answer
8 views

Manber's graph-partitioning algorithm implementation

I'm having trouble understanding a part of Manber's graph-partitioning algorithm, presented in A Text Compression Scheme that Allows Fast Searching Directly in the Compressed File. Generally speaking ...