Methods and principles of building "computer systems that automatically improve with experience."

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Do I need data standardization before t-SNE?

In my knowledge, t-SNE use sphere or diagonal normal distribution to represent the distance between point. So I guess that the distance is biased by the scale of respective features. What to my ...
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1answer
8 views

What should be the covariance matrices and weights for initializing EM/GMM with kmeans?

It's typical to initialize EM for Gaussian Mixture Models using the result of kmeans clustering. However, kmeans only gives you the means (centers) of the starting GMM, but EM initialization often ...
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7 views

How can I obtain the Simulations in CausalImpact package? [on hold]

Currently we are using your package CausalImpact to evaluate the effect of different interventions over the accident occurrence in different firms. I address to you in order to ask you if there is any ...
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1answer
48 views

PCA vs. Linear Regression

Am taking Ng's Machine Learning class on Coursera and in the below slide he distinguishes PCA from Linear Regression. He says that in Linear Regression, we draw vertical lines from the data points ...
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10 views

How to perform Sensitivity Analysis of Bayesian network using R?

I know there are similar techniques for Sensitivity Analysis for Random Forests. I am looking for something similar for Bayesian Networks. I have built the Bayesian Network using bnlearn package in R. ...
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7 views

Pre-training in deep convolutional neural network?

Have anyone seen any literature on pre-training in deep convolutional neural network? I have only seen unsupervised pre-training in autoencoder or restrcited boltzman machines.
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15 views

What is the difference between a conditional random field model and a particle filter?

Please can any one explain the difference between a CRF model and a particle filter?
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10 views

Issues in Testing SMO SVM

I am new be in SVM and SMO algorithm, I implemented SMO using the pseudocode provided in : “Fast training of support vector machines using SMO” by John platt. I am finding issues testing my ...
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1answer
56 views

Which language best to use for Machine Learning library? [on hold]

We have a body of theoretical work on nearest neighbors that we would like to implement and make the code publicly available. Question: what's the best language to use? We're considering java, python, ...
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2answers
38 views

“Non-naive” bayesian classification algorithms

Based on the problem description in this post: Relating parameters to a measured variable Based on a suggestion, I thought of studying the relationship between the parameters and a measured metric ...
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0answers
12 views

Why multivariate distribution is used to model weights (polynomial coefficients) for prior distribution?

Lately i have been reading Chris. Bishops work on bayesian linear regression what I am finding difficult to understand is why is he modelling w0 and w1 using multivariate gaussian distribution in ...
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19 views

Classifier that learns provided by only positive examples?

I was wondering if any of you has ever worked with classification/regression using only positive examples (one class). I would need such a system. The basic idea is that it is going to accurately ...
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2answers
23 views

Online learning that “forgets” older aspects learned? (short-term memory)

I am looking for an online learning classifier that is highly adaptable and has only short-term memory. I need such a think in a object tracking system with high-dimensional feature vectors. Maybe a ...
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18 views

The relationship between adaboost and gradient boosting

I am reading the chapter 10 of "The Elements of Statistical Learning 2nd ed, (ESLII)", where the Adaboost algorithm is explained by minimizing the exponential loss using stagewise additive modelling ...
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27 views

Tennis Analytics: How to Build Model Predicting Player Service Point Win %

I have collected a large amount of tennis match data including player names, court surface, player ranking points at time of match, handedness of player, point by point breakdown of match etc. I ...
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0answers
16 views

How large should the sample be to start using batch gradient descent versus normal equation

Suppose you want to train a multivariate linear regression on an n x m dataset. The runtime of determining your parameter theta = (theta0, theta1, ..., thetam) using the normal equations is ~ O(m^3), ...
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16 views

How do I “split” Gaussian mixture components when training EM/GMM based classifier?

In order to improve performance of my Gaussian Mixture Model based classifier, I was recommended to start with a single multivariate Gaussian, estimate its parameters, and "split" it into two ...
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20 views

SVM with non-negative weights

An SVM classifier can be obtained by solving the following, $\arg\min \frac{1}{2}\|W\|_2^2 + C\sum_i \max(0, 1-y_i (W^T\mathbf{x}_i + b))$ where $W$ is the hyperplane (or weights), $b$ is the bias, ...
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9 views

How to add cluster centers to the already transformed arrays with T-SNE Scikit Learn?

let's get this scikit original code, which is basically the one I'm using. My X is 2000x100 and in order to plot the clusters (plot on the right) I want to transform it with with the TSNE algorithm ...
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1answer
20 views

does sklearn rbm scale well with sparse high dimensional features

i am using scikit learn's RBM implementation. There are two problems: The running time is O(d^2) where d is the number of features. This becomes a problem in using high dimensionality sparse ...
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6 views

normalized mutual information implantation in java for community detection in graph range is not between 0 and 1 [on hold]

I write a program for calculating normalized mutual information for evaluate community detection. but i get values above 1 for nmi. normally it should be between 0 and 1. i implement formula in ...
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1answer
34 views

How to get probability from the confidence score in SVM

In liblinear library we can get confidence score (the distance between decision hyperplane) in SVM solver for a binary classification problem, but if i want a probability value for membership in any ...
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1answer
37 views

Is ROC or PR curve only the overall performance measure for classification

We can use ROC or PR curve to access the performance of the classifier,especially on imbalance data. But it is a curve with parameter threshold, even if we get a high ROC or PR performance, which ...
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11 views

How to use KL-divergence in naive bayes classifier to weight features?

I have a dataset consisting of 4 classes. I have implemented the Gaussian Naive Classifier (in Matlab). In the training phase I calculate the mean and variance for each feature and each class as well ...
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1answer
30 views

What's the measure to assess the binary classification accuracy for imbalance data

Now I have binary classification problem with positive samples roughly 100 times the number of negative samples. In this case the normal accuracy measure (predict == label) is not a good measure. What ...
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11 views

Does theano support multi-machine version [on hold]

We use theano in the GPU in a single machine, I am just wondering if it supports multi-machine programming so that the speed will raise up?
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25 views

Finding idf only for text mining

We find tf-idf for training phase in text mining, however, in test phase, we need the tf for each element in test set, but should use idf in train set, so is there any api in python that can calculate ...
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11 views

Inversely proportional version of a nearest-neighbour results vector - how?

Short version: Given an input vector D of n values, what are the different methods that one can use to return a vector W such that each value in W is in inverse proportion to the magnitudes of the ...
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0answers
21 views

tf-idf in text mining

I used sklearn of Python for getting tf-idf attribute in text analysis, but the problem is: I have about 78000 words in train_set, but the tf-idf matrix only has 39000 words. What is the problem ...
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13 views

How to use Weight vector of SVM and logistic regression for feature importance?

I have trained a SVM and logistic regression classifier on my dataset. Both classifier provide a weight vector which is of the size of the number of features. I can use this weight vector to select ...
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27 views

how can I fixed size of grid search in libsvm?

I'm trying to use libsvm to classify a database that contains 1000 labels using svm one vs rest . My goal is to get out the probabilities for each class and to perform accuracy. I know that the first ...
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1answer
24 views

What are the differences between delta rule and generalized delta rule?

I know that the delta rule is a gradient decent learning rule. But, what are the differences between these two delta rules? Thanks in advance.
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18 views

IKAnalyzer in text mining

Does anyone use IKAnalyzer for word segmentation in the preprocess for text mining? I have never loaded my own extended dictionary or stopword dictionary successfully. The following is the ...
3
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1answer
24 views

How to use log probabilities for Gaussian Naive Bayes?

I'm currently implementing a Gaussian Naive Bayes classifier. Of course if I'm doing classification by $$ \text{argmax}_{C_i} P(C_i)P(D|C_i), $$ then the probabilities can get very small. So I want ...
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17 views

Embedding in machine learning

What does word 'embedding' mean in machine learning? As I understand it is finding intrinsic dimensionality of the data. But how it works practically? Specifically, how does Gradient Boosted ...
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14 views

How can I get feature importance for Gaussian Naive Bayes classifier?

I have a dataset consisting of 4 classes and around 200 features. I have implemented a Gaussian Naive Bayes classifier. I want now calculate the important of each feature for each pair of classes ...
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18 views

Random forest: Possibility to derive the characteristics of the predicted value?

Decision Trees stratify the feature space into different regions and fit the model in each region. With this method it's not difficult to derive the caracteristics of each individual taking the ...
2
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1answer
62 views

How to set the dictionary for text analysis using neural networks

I want to use a neural network to do text analysis. If I use a large dictionary, then it will contain all the words in training and test set, but the size of the dictionary is too large which will ...
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1answer
21 views

Does Zero Observations Problem exist for Gaussian Naive Bayes?

I'm currently implementing a Gaussian Naive Bayes classifier. With a Naive Bayes classifier the zero observation or zero probability problem can occur, see e.g. point 11 on ...
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1answer
33 views

Is Representer theorem valid with constraints on coefficients?

By the representer theorem, we have that in a Reproducing Kernel Hilbert Space the function being learnt in a regularizer + loss function problem under some conditions, can be represented as $\sum_i ...
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0answers
9 views

How to use Galgo for variable selection. [closed]

I would like to make use of genetic algorithm implementation in R GALGO for variable selection and the result will be fed into multilayer neural network for classification.I do not know how to go ...
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15 views

How do I check or validate the RBM (Restricted Boltzmann Machine) Model?

I'm trying to implement RBM, then i used play tennis case to test the rbm. I've tried autoencoder before, and the result was good. Actually, I confuse with the function of RBM it self, i think it ...
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1answer
27 views

Neural network to tag multiple textual topics in a single document

I want to use a neural network to do some topic analysis in a textual corpus. I have used neural networks before where there is a clear decision boundary between the category to which some observation ...
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0answers
21 views

What is a good non cryptographic Hash for string feature translation?

What would be a good non cryptographic Hash function to use for converting string features to a numerical representation for feeding into machine learning algorithms? To explain the scenario my ...
0
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1answer
15 views

2d basis functions which are smooth and localized and sum up to unity?

We are looking for a set of basis functions for representing image-data which consists of local ‘blobs’ which tile the space and which sum up to 1 at each point in space. For 1-dimensional data, ...
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1answer
24 views

Representing signals as feature vectors for deviation detection

I want to monitor (automatic-)gearbox failures on some vehicles. For each vehicle I have a captured signal representing the selected gear at each one millisecond (the values are discrete between 0 and ...
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1answer
34 views

“One sided” classifier

Below was tried in R, but any general solution would be highly appreciated: I have 2 class samples (both classes are balanced). I want to create a classifier, where I only care about 1 class (So, if ...
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0answers
51 views

What types of job opportunities are out there for data mining and machine learning? [on hold]

I have asked a question about skills which lead to data mining/machine learning field (What are Ideal IT skills/programming languages for data mining/machine learning/AI field?), but I feel like my ...
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1answer
41 views

How do I implement missing value patterns?

I have a training data set and I was able to find some interesting patterns in the missing values, and I used binary variables in order to represent the missingness. I am going to train a model, say a ...
3
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31 views

Concept of fitting cubic splines

i am reading the elements of statistical learning, and the following diagram is included on page 262. i interpret the text (potentially incorrectly) that the fitted line $\mu(x)$ is a linear ...