Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [algorithms]

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

0
votes
0answers
10 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
votes
1answer
25 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 ...
1
vote
1answer
14 views

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

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 ...
2
votes
0answers
25 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
votes
1answer
62 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 ...
0
votes
2answers
240 views

What's the best algorithm type for low-dimensional grouping

I'm looking for some advice on directions to head in a project I'm working on. Basically what I want to do is identify general (of varying size) groups in a 2-D grid of points belonging to one of ...
3
votes
1answer
133 views

Reference summarizing various machine learning algorithms' computational complexity

For example, suppose you train a linear regression model using the Normal Equation, on a training set $\mathbf{X}$ containing $m$ instances and $n$ features. The Normal Equation requires computing $(\...
3
votes
1answer
817 views

Cholesky update for removing row

What is most efficient way to updating cholesky factorization of for removing a column from the matrix? T = Chol(X' *X) If I remove a column from X, how to ...
9
votes
3answers
12k views

Apriori algorithm in plain English?

I read wiki article about Apriori. I have the trouble in understanding the prune and Join step. Can anyone explain me how Apriori algorithm works in simple terms(such that Novice like me can ...
0
votes
0answers
12 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: ...
6
votes
3answers
991 views

Can sub-optimality of various hierarchical clustering methods be assessed or ranked?

Classic agglomerative hierarchical clustering methods are based on a greedy algorithm. This means that they (many of them) are prone to give sub-optimal solutions instead of the global optimum result, ...
1
vote
2answers
51 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?
0
votes
0answers
31 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 ...
4
votes
1answer
311 views

Lasso ||a|| and “General Lasso” ||Da||

Ryan Tibshirani introduced once a more general type of Lasso, where the regularizer is $$\parallel D \alpha \parallel_1$$ instead of $\parallel \alpha \parallel_1$. See paper However, there is nearly ...
0
votes
2answers
351 views

Customization of a standard Bell Curve

Hopefully this isn't a duplicate, I've tried to search for similar things, but to no luck. I'm curious on how you would computationally compute a random distribution of numbers that follows a bell ...
7
votes
3answers
2k views

Collaborative filtering and implicit ratings; normalization?

I would like to use the time a user spends viewing an article as an implicit rating of how much the user likes the article. My question is how do I normalize this information across all users. At ...
4
votes
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 ...
1
vote
1answer
341 views

Finding outliers in multiple dimensions

I'm working on dataset which isn't normally distributed. It contains three dimensions: cost, discount and profit. I'm trying to find outliers in all these dimensions. I used $\text{z-score}$ to find ...
1
vote
1answer
351 views

clustering for categorical data with one column for observations

I'm trying to cluster a dataset using 4 variables, all of which are categorical variables. I'd also like to include another numerical variable that's actually the number of observations of another ...
0
votes
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 ...
0
votes
0answers
14 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
votes
0answers
12 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'...
0
votes
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 ...
0
votes
0answers
6 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 ...
5
votes
2answers
1k views

Open source implementation elastic net in C or C++

Can anyone provide or point me to a freely available implemention of Elastic Net in C or C++?
0
votes
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
3answers
89 views

Machine Learning that improves our ML algorithms?

I know very little about ML, all I know is what I read on Flipboard or watch on youtube. So from what I know I think ML is a series of algorithms based on statistics and evolution, such that they try ...
1
vote
1answer
74 views

What do you call this technique?

I'm a worker in the energy business, and I'm trying to see if we can predict whether a customer will complain given that they called in about x, y and z. My team and I are new to data science. In the ...
0
votes
1answer
367 views

Algorithm to find common sequence

Assume that "1,2,3" are the ids of users, active means that person visited the stackoverflow in last one month (0=passive, 1=active), and there are positive and negative votes. ...
1
vote
1answer
62 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 ...
0
votes
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 ...
6
votes
1answer
412 views

Evening out a set of buckets

(I am not strong in statistics so please forgive me if I don't use the correct terms here) Let's say I have a book with many (1000+) sections, and each section varies significantly in the number of ...
0
votes
0answers
29 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
votes
2answers
65 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: ...
1
vote
1answer
21 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 ...
0
votes
0answers
49 views

Examples of machine learning algorithms where it is not recommended to scale/normalise/mask the data?

We need to share company internal data with a vendor. In order to protect sensitive data, we have masked personal information such as customer id etc. We are discussing the pros and cons if we should ...
9
votes
1answer
499 views

Expectation Maximization Clarification

I found very helpful tutorial regarding EM algorithm. The example and the picture from the tutorial is simply brilliant. Related question about calculating probabilities how does expectation ...
0
votes
0answers
20 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
votes
0answers
28 views

Computing Wassertein Distance

For two probability measures $\mu$ and $\nu$, the Wassertein Distance is defined as $$W_p (\mu , \nu) = \left[ \inf\limits_{\gamma \in \Gamma} |x-y|^p \, d\gamma (x,y) \right] ^{\frac{1}{p}} \, , $$ ...
13
votes
1answer
17k views

Generating values from a multivariate Gaussian distribution

I am currently trying to simulate values of a $N$-dimensional random variable $X$ that has a multivariate normal distribution with mean vector $\mu = (\mu_1,...,\mu_N)^T$ and covariance matrix $S$. I ...
0
votes
0answers
20 views

Question about PyTorch tutorial

In this PyTorch tutorial the backprop to compute gradients is shown with the following code: ...
0
votes
1answer
60 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 ...
19
votes
2answers
1k views

Simulating time-series given power and cross spectral densities

I am having trouble generating a set of stationary colored time-series, given their covariance matrix (their power spectral densities (PSDs) and cross-power spectral densities (CSDs)). I know that, ...
2
votes
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 ...
0
votes
0answers
17 views

Optimize function on two stages

I have a non-linear cost function (which I do not know its analytical derivative and it is pretty hard to be computed). The function takes 8 parameters. I need to minimize this function using some ...
0
votes
0answers
12 views

How to optimize activity scheduling with dependencies and resource requirement?

I have a list of activities $A=[a_1 \cdots a_n]$. Each activity has a duration $d$ and a resource demand $r$. The resource availability varies over time. Moreover, each activity may have a ...
1
vote
0answers
20 views

Learn how to arrange subsets

I have the following problem and I'm looking for a way to solve it with an machine learning algorithm or something like that. I got a huge dataset and the data looks like that: Row 1 = {{0},{4,4,4,4,...
2
votes
1answer
53 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 ...
11
votes
3answers
7k views

What fast algorithms exist for computing truncated SVD?

Possibly off topic here, but there exist several (one, two) related questions already. Poking around in the literature (or a google search for Truncated SVD Algorithms) turns up a lot of papers that ...
0
votes
1answer
26 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