Computational Science Stack Exchange
Computational Science Stack Exchange

Questions tagged [machine-learning]

Machine learning, a branch of artificial intelligence, is the science of getting computer systems to meaningfully act without being explicitly programmed by human.

122 questions
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Apply PCA on very large sparse matrix

I am doing a text classification task with R, and I obtain a document-term matrix with size 22490 by 120,000 (only 4 million non-zero entries, less than 1% entries). Now I want to reduce the dimensionality by utilizing PCA (Principal Component…
Ensom Hodder
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Looking for an understandable discussion of creating Maximum Entropy classifiers

Texts, articles, and papers on Maximum Entropy Classifiers tend to come in two varieties: the more popular "upper level", and the more technical. The popular variety are good at explaining the Maximum Entropy concept and why such classifiers are…
winwaed
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Applying same feature selection to multiple data sets with Weka

I am using the Weka workbench to train a protein fold classifier. I imported my training data into Weka and performed PCA-based feature selection. This seems to have worked fine, but now I cannot evaluate my trained classifier on the test data…
Daniel Standage
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How to filter customer voice from customer - agent conversation recordings?

I have a doubt on the project I'm working now. Actually I want only customer voice from the recordings which contains customer-agent conversation.But I have no idea to filter customer voice from customer - agent voice recording. Could someone please…
sowmiya
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How To Interpret PCA Points Labeled With Specific Data Dimensions

I've done some PCA on my own, and am familiar with the basic concepts of how PCA components are calculated and applied. However, I'm working on a research project and am confused as to how to interpret a common type of graph I've seen across many…
Zachary Rohman
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Neural Networks: what's the point of learning features that don't linearly separate?

Unless I'm mistaken, deep neural networks are good for learning functions that are nonlinear in the input. In such cases, the input set is linearly inseparable, so the optimisation problem that results from the approximation problem is not convex,…
Alexandre Holden Daly
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How to setup a Neural Network?

I have a completely beginner question about the setup of artificial neural networks. Basically it boils down to: How do I put in data and get results? For example, classification: let say I have 10 input features, all numerical, and 5 output…
David Williams
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How to create synthetic data from known weights

I'm doing some machine learning where I have lots of data and through optimization I'm trying to learn the weights for the model. I'd like to check that my learning actually works correctly. For that I can create a set of known weights. My question…
siamii
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Tracking channel states using Machine Learning

I am new in AI and would like to apply machine learning to estimate the channel states. I have a set of data. It is a matrix of 10000*8. Each row of this matrix is regarding a time step, i.e., 1st row = current time step (t), 2nd row = next time…
Susan
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neural networks: multilayer on-off perceptrons

This article says that all any multilayer perceptron with a linear on-off functions for all the neurons can be reduced to a two-layered perceptron. Now, consider a two input/one output perceptron. The theory says that it impossible to model XOR…
khachik
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Finding most informative feature subsets given dataset, clustering algorithm and gold standard partition

I have an $n \times m$ matrix of data $\mathbf{D}$ as well as a $k$-partition $P$ of $n$ indices each representing a row in a dataset. Assuming an arbitrary clustering algorithm $A$, I would like to find a subset $F$ of $\{1,\ldots, m\}$,…
user8781
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Want to make sense of array dimensions in logistic regression algorithms

I am trying to implement a simple logistic regression algorithm from scratch in python (for learning purposes). Every article I've seen online so far presents the following expression for $z$ (argument of the sigmoid function): $$z = \theta^T\cdot…
user32882
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How to make the following data separable for the classification into three classes?

The figure below shows the PCA projections of inputs which are 14 meteorological features, (i.e. wind, temperature, humidity, pressure, and so on.) I would like to use any technique to make it more separable than this, The ISOMAP method is also used…
mhdella
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What library can you use to detect personalities from comments?

I have a bunch of comments from my website that I want to use to build a profile of someone's personality based on the topics they chose to write in and the their specific comments. I know that this entails natural language processing but I have no…
user299709
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Neural Network - single layer perceptron for multiple classes

For activation function in neural network, I have used the function $$\frac{1}{2}(\sin x +1) \enspace .$$ But this will give me the value of either 1 or 0, allowing me to classify only 2 classes. What if I want to classify more than 2 clusters of…
girl101
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