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

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Bootstrapping test set?

Let's say I have a classification problem with a small and fixed test set. If I train a classifier and report the accuracy on this test set, I know that this estimate has a high variance. Does it make ...
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14 views

Training instances importance in Random Forest?

Is it possible to determine the importance of the training examples in Random Forests, analogously to what's done with predictors? Basically the idea would be to find important samples in the data, ...
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7 views

measure the inter-relationship among a set of multi-variate data points

Given a group of multivariate data points, are there any ways to formalize/quantify the relationship of one given point comparing to other data points in this group. Clustering maybe one approach. But ...
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How can I apply discriminant analysis (multivariate) if my data is not normally distributed?

As LDA and QDA assume normality and homocedasticity, and my data is not that well behaved... is there any other kind of robust technique I could use? Could applying box cox transformations and then ...
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How common is it to train each network independently then train end-to-end in a neural network?

Say that I had 3 autoencoders stacked on each other. How common is it to ...
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1answer
15 views

How does data augmentation reduce overfitting?

I'm trying to understant the benefit apported by the step of data augmentation in a classification algorithm. I have a vector of hexadecimal strings and a column vector containing the label ...
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1answer
17 views

What happens inbetween switching test and training sets in k-fold cross validation

The general idea of k-fold cross validation is to partition your test data from your training data, then within your training data you make another partition where all but one of those partitions are ...
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19 views

how to preprocess/feature stacle multimodal input data?

I am wondering how to normalize data for the use of SVMs etc. that has a clear non Gaussian, i.e. non unimodal distribution. I wrongfully scaled the data by subtracting the mean and dividing the std ...
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21 views

Interaction between two random variables [on hold]

I have a machine learning system called Sys. Sys uses a variables set (Var) applied to a ...
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1answer
29 views

What method for classification with 24 variables, 14 categories and 100,000 obs.?

I have a dataset with more than 100,000 observations (rows) and 24 variables in which 23 are continuous and one is categorical variable. The categorical variable has 13 categories (1, 2, 3, ..., 13) ...
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12 views

Using sentiment data to predict stock prices

I have implemented a model to predict "last" price of stock of 5 days ahead. I have used RandomForestRegressor. In addition to this, I have a data set of sentiments. It is the data from social media ...
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10 views

statistics metrics or machine learning methods to quantify the relationship between a point and a group

There are several data groups: A1 = { A11, A12, A13, …, A1n} A2 = {A21, A22, A23, …, A2n} .. … … Am = {Am1, Am2, Am3, …, Amn} Here ...
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Is this the right approach to sequence learning with a LSTM?

I am currently learning to use Keras and am trying my hands on NILM (Non-intrusive Appliance Load Monitoring). In NILM the goal is to disaggregate the whole house power data into single appliances. I ...
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validating a gaussian process fitted to data

I am relatively new to applying Gaussian processes to data. I come from a math background but the most popular literature on it seems to be from a machine learning perspective and not from a ...
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7 views

Evaluation of a binary classifier in regards of rounding, taking average scores

I'm using scikit-learn to evaluate a binary classifier: There are 2 Methods to get the Precision, Recall and F1 scores: 1.classification_report: ...
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Confused about the Convergence Theorem for a Generalized MDP

Sorry for the wall of text below. It will seem like forever before my question comes up, but I think the context is much needed to avoid confusion. According to "A Generalized Reinforcement Learning ...
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12 views

Why do we use expectation in reinforcement learning? [duplicate]

In reinforcement learning we use lot of expectations, what's the logic behind them? Like in reward function, we use expected return instead of return, in value functions V and action-value functions ...
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22 views

Regression or time series model to predict trend

DATA I have the following data at hand: data about internet usage, per hour, per user, per part of the day (morning, afternoon, evening); the category of websites visited and their duration; ...
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7 views

How does gbm (in r) control the sub-sampling of predictor variables? [on hold]

In gbm, the parameter, bag fraction, is used to randomly select subset of observations. And the sampling could be contorlled by set.seed() before gbm (Please correct me if I was wrong). But is there ...
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10 views

Applying support vector regression to vector-valued functions?

So, just as a preface: this is my first time posting to this site, and I am also a machine learning beginner, so I apologize if my question is dumb or if I do something wrong, format-wise. Alright, ...
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7 views

Ordering by importance when plotting partial functions from forestFloor

I would like to start by saying that I am relatively new to the R packages randomForest and forestFloor and I have never posted a question on here - so please be temperate. I have been working on an ...
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26 views

why are RNNs unrolled?

When training simple RNNs, say for language models (predicting next char from sequence of past chars), is it necessary to unroll the RNN or can we just train with a single cell? It's not clear to me ...
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8 views

correlation between score and variable across different methods

I am using three different Machine learning methods to segment images, with a score for each image. I would like to show that there is a relationship between the score and the image, rather than the ...
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1answer
43 views

What does penalizing a function mean, and how is it implemented?

I've alway seen this statement in academic papers, blog posts, documentation, etc. but I've never understood it. What does it mean to penalize a function, and what is a concrete example of it? Just to ...
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3answers
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Why do we use expectation in reinforcement learning?

In reinforcement learning we use lot of expectations, what's the logic behind them? Like in reward function, we use expected return instead of return, in value functions V and action-value functions ...
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0answers
18 views

Global Minima and Local Maxima in Random Forest Classifiers in R [on hold]

I am learning Random Forest Classifiers and I want to know how can we determine the Global Minina, Local Minima, Local Maxima of a Random Forest classifier. Can some one help with this?
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Bag of Visual Words: the number of words is equal to the number of k-means centroids?

I was reading these slides about Bag of Features (BoF), in particular at slide 23: A visual vocabulary of 1M words is generated using an approximate K-means clustering method based on randomized ...
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What are common ill-conditioned problems/mistakes in linear regression? [on hold]

Many problems are ill-conditioned and cannot be reliably solved using double precision computer systems. Here is what I know that could happen in linear model, that the problem is ill-conditioned and ...
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47 views

Ridge Regression Plot by Direct Calculation [on hold]

I would like to emphasize that ridge regression coefficients is becoming close to zero as the penalty parameter $\lambda$ increases, but without using R package (glmnet, lm.ridge). My procedures are: ...
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14 views

About installing Theano [migrated]

I hope this question is relevant to this community as Theano is increasingly a standard software to do machine learning. So I have been trying to follow the instructions here, http://deeplearning....
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11 views

undersampling-unbalanced data

what are the correct steps for undersampling in classifying models? for instance if a have an unbalanced dataset with 950 non event and 50 events I will undersample creating a dataset with a 50-50% ...
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Specifying a good goal in Multi-agent RL

I am reading a survey paper on Multiagent reinforcement learning (MARL) by Busoniu, Babuska, De Schutter (IEEE Transactions on Systems, Man and Cybernetics March 2008). Under 'Challenges in MARL', ...
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9 views

Programs to read an arbitrary image and convert it to the format of MNIST dataset [on hold]

I want to make a program that turns a given image into the format of the MNIST dataset, as a kind of exercise to understand the various preprocessing steps involved. But since the description of how ...
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1answer
66 views

A problem with interpretation of principal components as linear combinations of features

I often see the principal components of PCA described as "linear combinations of the original features". Say we want to compute the principal components of our $m \times n$ design matrix $A$ ($m$ ...
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16 views

How to do sentence boundary detection? [on hold]

I have a string as My name is sushil feeling bad My age is 30 and hobbies are none thanks for asking me name varun i am good at cricket and my age is 40 i have done a lot of work in research area , ...
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Comparing the performance of two classifiers for statistical significant differences

I am aware that there are similar questions asked on Cross Validated, however, this differs slightly. Say that I have one dataset, which I want to use to train two classifiers A and B (supervised ...
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25 views

How to deal with categorical target variable that has more categories in prediction than training?

I'm building a logistic regression model and found out that with my categorial target variable there are more categories in my prediction set than my training set. To be clearer: In e.g. my training ...
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Why doesn't the hidden state of a neuron network provide better dimension reduction result than original input?

I just read a great post here. I am curious about content of "An example with images" in that post. If the hidden states mean a lot of features of the original picture and getting closer to final ...
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In simple terms, what is a radial basis machine (RBM) modeling?

I stumbled on this term while trying to read this research article: http://clincancerres.aacrjournals.org/content/21/1/175 I don't have a background in statistics, so simple terms would be nice. Also,...
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1answer
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Twitter Classification of tweets related to Ebola into 21 custom categories

I have a lot of twitter data (4GB) related to keyword Ebola. I want to classify the tweets into 21 categories. Categories :- Death - tweet is about death Health Care Workers - tweet is about ...
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2answers
42 views

Recommendation using Random Forest [on hold]

I am trying to write my own recommender system. I have data set of user-item rating matrix. But I do not have profile information about either items or users. I already built pure CF using cosine and ...
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20 views

Classification(Machine Learning) or Survival Analysis

I am working on building prediction model for disk failures (time taken to occur a disk failure and what parameters could strongly affect disk failures). I am bit confused on- What data ...
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23 views

Product suggestions based on what users have also bought

We need to train a model that when given an input of a product name and group, it outputs product suggestions for what users frequently buy together. We have product data stored like: ...
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7 views

How to create machine learning model for sparse 1D data?

I want to predict the frequency of Dataset 1 from the information in Dataset 2. Dataset 1: List of 1D points on a flat number line. Number line ranges from 1 to 3 billion (yes billion). Dataset 2: ...
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26 views

Bayesian Information Criterion(BIC) for gaussian Mixture Models

Say that i have two classes, A and B and some training data $(x_i, y_i), y_i \in {A, B}$. My goal is to fit a mixture model into each class individually and calculate the BIC for the model. The BIC ...
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8 views

Is there any Revolution R functions ( Rx) functions available for Survival Random Forest Analysis? [on hold]

I have R code which does Survival Analysis using Random Forests. It was taking huge amount of time. Is there any way to parallelize the operations using either Rev R Rx functions or any other way ?
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1answer
38 views

Regularized linear model: adding special constraints to the coefficient

I understand we can add $L_1$ or $L_2$ regularization to linear regression (Lasso and Ridge regression). In addition, it is possible to restrict the coefficient to be integers (see this post). ...
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time series classification of an event either happening or not happening using machine learning techniques

I have sensor data that I would like to use to classify whether an an event (giving birth) is about to occur within (2-4hrs) in an animal based on various metrics collected by the sensor(activity ...
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How to treat training example with multiple values for a feature

Problem Setting Suppose I am given a data set with the following: a user_id used to identify different users a list of books ...
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Can anyone help me understand the proof of the inequality that relates shatter number and Rademacher Complexity?

Let $F$ be a collections of binary function. $s(F, n)$ be the shattering number of $F$ defined as $sup_{z_1...z_n}|F_{z_1,...,z_n}|$. Can anyone explain the proof of the following inequality?