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

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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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12 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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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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0answers
18 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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35 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
26 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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19 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
25 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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19 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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17 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
65 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 ...
1
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1answer
23 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
34 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
16 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 ...
1
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1answer
29 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
17 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, ...
0
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1answer
27 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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52 views

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

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 ...
1
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1answer
43 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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0answers
34 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 ...
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1answer
28 views

spike and slab models

Kevin Murphy discusses in this book (http://www.cs.ubc.ca/~murphyk/MLbook/index.html) the spike-and-slab model. I am struggling to understand the prior linked to this model. Why, if $\gamma$=0, and we ...
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1answer
16 views

Training lstm a sequence one item at a time

I am trying to train an lstm with a sequence and get the sequence classification for the whole sequence. I have sequences of varying length so I have one input neuron and I am feeding one item at a ...
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0answers
40 views

How does one extend radial basis function (RBF) networks formally from regularization but with vector valued outputs?

I was reading the following paper on hyper & radial basis function (HBFs & RBFs) networks and also this one that kind of summarizes the first one and was trying to understand how to extend ...
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1answer
45 views

Random Forest, dependent measurements

I have a following quiz: A random forest is used for classifying the disease state of patients based on measuring multiple genes. The dataset consists of 100 genes and 50 patients. However, ...
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16 views

Tree not predicting all factors

I'm using the "tree" function to fit a model to predict a factor "Output" based on A, B, C, D and E ...
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0answers
4 views

Stop a machine learning training but keep current state of the model with Vowpal Wabbit [migrated]

I am currently running a training phase using vowpal wabbit. The data set is big (4GBytes), and it has already run a whole night long. It is still training, and I don't know how many days it could ...
3
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1answer
71 views

naming convention: what does GLM stand for?

I encountered the term "Global Linear Model" which has the same abbreviation as "Generalized Linear Model". Since I couldn't find useful information on the former, my question is whether the two ...
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2answers
83 views

What measure of training error to report for Random Forests?

I'm currently fitting random forests for a classification problem using the randomForest package in R, and am unsure about how to report training error for these ...
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0answers
20 views

Problems with classification in imbalanced datasets

I often read about the problematic of doing classification in imbalanced datasets and methods to address it. Namely, off-the-shelf classifiers learn to minimize some form of total miss-clasffication ...
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0answers
12 views

Interpolation of Data Value using Optimized Weighting of Its Features

I have a question regarding "Interpolation" / "Prediction" of a value. Assuming we have a data set $ { \left\{ \left( {x}_{i}, {y}_{i} \right) \right\}}_{i = 1}^{N} $ where $ {x}_{i} \in ...
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6 views

How to classify different skeleton poses into a predefined pose or other poses using Kinect?

I'm using Kinect for windows and the input is the skeleton frame joints locations. As a result, I can track different joints locations in time. I need to detect this pose: With hands straight ...
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1answer
43 views

Class weights in caret

I'm using the R package caret to generate classifiers using a variety of different models on an imbalanced dataset. To overcome the class imbalance problem, I am using the "weights" parameter in the ...
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1answer
32 views

Feature selection in a “Noisy” environment

My first question - This might be a basic question but I have yet to find an answer; when choosing the features for my model, I have encountered certain features which are vectors themselves. (e.g. ...
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27 views

What's the difference between logistic regression and perceptron?

I'm going through Andrew Ng's lecture notes on Machine Learning. The notes introduce us to logistic regression and then to perceptron. While describing Perceptron, the notes say that we just change ...
0
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1answer
21 views

What are the different frameworks for solving regression problems in Machine Learning (like GLMs)?

I'm going through Andrew Ng's lecture notes on Machine Learning. The notes start with introducing linear regression and intuitively explaining what the cost function for the problem should be and how ...
0
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1answer
54 views

Is my understanding of Generalized Linear Models correct?

I'm going through Andrew Ng's lecture notes on Machine Learning & I just learnt about Generalized Linear Models there. I want to check if I know correctly what Generalized Linear Models are. ...
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0answers
12 views

Deriving Linear Regression update rule: Why do we set the derivative of cost funtion to 0 to minimize it?

(This question may be more about Math in general but I have a specific context in mind and hence am asking this here as opposed to math.stackexchange) I'm going through Andrew Ng's lecture notes on ...
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0answers
16 views

Model for irregular time series

I recently started working with regularly sampled time series, i.e. evenly spaced time series. However, I would like to move to irregular time series, i.e. unevenly sampled time series. I have looked ...
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55 views

How should one learn the centers for an hyper basis function network (HBF)?

I was reading the following paper on hyper basis function (HBF) (similar to radial basis function RBF network) and was trying to figure out how one learns the movable centers of the hyper basis ...
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1answer
32 views

Binary Classification vs Multi-class Classification

In the scenario that I have a binary classification problem, and use a binary classifier to train and test my model, assuming everything else is constant, would using a multi-class classifier with 2 ...
0
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1answer
36 views

Regression model for edge-sensitive data set

I have data sets in which important information is allocated in the edges, which are also very sensitive to inaccuracies. I would like to find a regression model based on edge recognition that brings ...
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216 views

Learning algorithm to define prediciton region to maximize score

The title may not too fitting but here is the problem. You have a sample of data with each data point being an x,y coordinate and a score. The goal is to create a loop which encloses the values as to ...
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15 views

What does “task-dependent clustering” mean?

I was reading the following paper on hyper basis function (HBF). Its about how one can use moving centers instead of data points as the centers of radial basis functions (RBFS). In the abstract they ...
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1answer
93 views
+50

Relative variable importance for Boosting

I'm looking for an explanation of how relative variable importance is computed in Gradient Boosted Trees that is not overly general/simplistic like: The measures are based on the number of times a ...
0
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0answers
18 views

Mixtures of experts

I am trying to self-study and understand "mixture of expert" models, as desribed per below: . Is my intuition here correct that the $\rho(z_i|x_i,\theta)$ is a probability vector of length k, with ...
0
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1answer
26 views

How to find a Information Gain for Numerical Values

I have 4 class and four sets of features extracted from the huge data extracted from Real Time data acquisition system. . In above table, there are 4 sets of the features for each class. (C1, C2, C3 ...
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3answers
43 views

Is setting lambda equal to zero the same thing as not applying regularization at all?

If I set the regularization parameter to 0, does it essentially mean I'm not applying regularization (I've boxed the regularization bits in red)? Also, what is this type of regularization called?