Questions tagged [algorithms]
An unambiguous list of computational steps involved in finding a solution to a class of problems.
733
questions
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What is the method should I use to calculate similarity in a data set with outliers that must be included?
Information:
So I have a data set with 18 vectors with 167 components, each of with has a value with a range of $[-2, 2]$. I am trying to calculate the similarity between one arbitrary vector in ...
1
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1answer
27 views
Decision Trees - how does split for categorical features happen?
A decision tree, while performing recursive binary splitting, selects an independent variable (say $X_j$) and a threshold (say $t$) such that the predictor space is split into regions {$X|X_j < t$} ...
2
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0answers
16 views
Minimize element-wise distance between two sets of points in R^n
Given two ordered sets $X, Y$ each containing $m$ elements in $\mathbb{R}^n$, I'm looking for a permutation $\sigma$ of the second set that minimizes
$$\sum_{i=1}^m \lVert X_i - Y_{\sigma(i)} \rVert$$...
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3answers
83 views
What kind of statistical model I should use?
Here is the project that I'm currently working on it and would be more than happy if I can get your opinion about it.
The project is about dispatching the EMS helicopters to the incident locations to ...
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0answers
10 views
Dynamic Time Warping - building a distance matrix with any distance that we want?
I am new to Dynamic Time Warping. I understand that we build a distance matrix and then try to find the cheapest path from starting to ending point. Typically euclidean distance is used to calculate ...
1
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2answers
28 views
How to classify time series trends into 2 groups: “contain seasonality” and “doesn't contain seasonality”
I'm optimizing prediction model for time series data trends. Each trend may have seasonality effect or may not. I want to classify each trend into one of the following groups: "seasonality" or "no ...
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0answers
5 views
How to handle unknown terminals in lexical parsing? how to smooth unknown terminals?
I have a treebank of setences. I derive a PCFG from the treebank and with MLE the probabilities of each rule. with those rules and probabilities I'm using CYK parser to get the most probable parse ...
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0answers
13 views
How is jaccard similarity used to find the similarity between Bootstrap samples when measuring stability of EM?
Im reading the answer on "how to determine number of clusters in EM algorithm". How to tell if data is "clustered" enough for clustering algorithms to produce meaningful results?
One of the ...
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0answers
8 views
Measure effectiveness of algorithm (plot included for clarification)
I have written a short algorithm that computes the "comovement" of a time series. My problem is what method to use to measure how accurate this algorithm is. Ideally it should only have negative lines ...
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0answers
61 views
Label Switching and Pivot method
I am working on the so called label switching problem in Bayesian inference with Gaussian Mixture Models.
To put in a nutshell, when your favourite MCMC samplers estimates the parameters of your GMM,...
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0answers
9 views
Supervised learning vs Regularity based learning
I have some confusion about regularity based learning and supervised learning. Are they in essence, not the same thing?
We have some labelled data, and our algorithms are structured based on learning ...
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0answers
14 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 ...
6
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1answer
140 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 ...
2
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0answers
33 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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0answers
39 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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0answers
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 ...
0
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1answer
71 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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0answers
29 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
29 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 ...
3
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0answers
90 views
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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0answers
72 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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0answers
13 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
19 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 ...
1
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1answer
86 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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0answers
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 ...
0
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1answer
40 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 ...
2
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0answers
27 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
71 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
20 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
53 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:
...
2
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2answers
516 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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0answers
39 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 ...
0
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1answer
22 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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0answers
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 ...
2
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0answers
37 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
44 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 ...
1
vote
1answer
518 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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0answers
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
56 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-...
1
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1answer
34 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
80 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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0answers
25 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)....
2
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0answers
34 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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28 views
Question about PyTorch tutorial
In this PyTorch tutorial
the backprop to compute gradients is shown with the following code:
...
0
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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 ...
