Questions tagged [classification]

An instance of supervised learning that identifies the category or categories which a new instance of dataset belongs.

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382 views

Deciding about dimensionality reduction, classification and clustering?

Could you please help me to understand it because I'm not sure if I got it correctly. Let's say I have a dataset, of persons, with 100 features, various characteristics like height, weight, age, etc. ...
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3answers
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Same SVM configuration, same input data gives different output using Matlab and scikit-learn implementation of SVM, in a classification problem

I have a classification problem with 60 data points in a 2-dimensional feature space. The data originally is divided into 2 classes. Earlier I was using Statistics Toolbox of Matlab so it was giving ...
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1answer
603 views

Classify Customers based on 2 features AND a Time series of events

I need help on what should be my next step in an algorithm I am designing. Due to NDAs, I can't disclose much, but I'll try to be generic and understandable. Basically, after several steps in the ...
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1answer
74 views

Mine webshop history for clusters

I've no experience in data science so this will be one of those questions... I have data from >100k purchases made via a webshop regarding a catalogue of around >100 items. The history of purchases ...
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3answers
927 views

Machine learning algorithm to classify blog posts

So I have a large collection of blog posts containing title, content, category, ...
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1answer
299 views

Are there other large margin classifiers than SVMs?

When reading about SVMs (e.g. on the German Wikipedia) there is a sentence like "an svm is a large-margin classifier). Are there other large margin classifiers than SVMs?
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1answer
203 views

Dense text representations

I did a lot of Googling but could not find a paper that presents an algorithm which will produce dense feature vectors for short text input. I would be happy to find feature extraction algorithm which ...
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1answer
3k views

Sentiment Analysis algorithm in Weka

I have an assignment, i have to collect movie reviews and classify them with poz neg notr tags, and turn them info arff files. I did all of this stuff with regex etc. But for experiment i have to ...
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2answers
7k views

SPARK Mllib: Multiclass logistic regression, how to get the probabilities of all classes rather than the top one?

I am using LogisticRegressionWithLBFGS to train a multi-class classifier. Is there a way to get the probability of all classes (not only the top candidate class) ...
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1answer
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SPARK, ML: Naive Bayes classifier often assigns 1 as probability prediction

Hi I am using Spark ML to optimise a Naive Bayes multi-class classifier. I have about 300 categories and I am classifying text documents. The training set is balanced enough and there is about 300 ...
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2answers
3k views

Is $R^2$ an appropriate evaluation metric for k-Nearest Neighbors?

I found a source that stated that $R^2$ is the ”percentage of the response variable variation that is explained by a linear model.” (Source) Since kNN is not a linear model (it is nonparametric), is ...
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3answers
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Gradient boosting algorithm example

I'm trying to fully understand the gradient boosting (GB) method. I've read some wiki pages and papers about it, but it would really help me to see a full simple example carried out step-by-step. Can ...
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5answers
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Is there a difference between “classification” and “labeling”?

Until recently, I thought that "labeling" and "classification" are synonyms. But when I started another question about terminology in computer vision I thought about it: Is there a difference between "...
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2answers
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How do I perform Naive Bayes Classification with a Bayesian Belief Network?

I've been writing a java library that I want to use to build Bayesian Belief Networks. I have classes that I use to build a Directed Graph ...
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0answers
116 views

Using classification to find the best support and confidence measure in associative rule mining

I have been trying the find the best support and confidence values for associative rules mining. I came across the following approach from an answer on Quora - Picking the "appropriate" values for ...
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4answers
2k views

oversampling plus down sampling using smote not working on random forests

I am trying to solve a classification problem on a highly imbalanced data set. I am using SMOTE to over sample the minority samples and down sample the majority ones. After creating a balanced data ...
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3answers
15k views

Unbalanced classes — How to minimize false negatives?

I have a dataset that has a binary class attribute. There are 623 instances with class +1 (cancer positive) and 101,671 instances with class -1 (cancer negative). I've tried various algorithms (Naive ...
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1answer
285 views

Improving SVM binary classification model on new dataset

I am working to create a SVM binary classifier for classification of Tweets based on news class "Crime" and "Non Crime". I have downloaded a dataset of 6400 rows from various sources and training my ...
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1answer
9k views

What is a benchmark model?

I am working on a breast cancer dataset (http://kdd.org/kdd-cup/view/kdd-cup-2008). I need to perform classification on the data using C4.5 algorithm, after doing any necessary pre-processing. A ...
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1answer
78 views

how to make new class from the test data

I have a list of accounts as data set and I need to group the accounts that refer to the same user using many features. I'm thinking to use machine learning( but I'm new in this domain), because I ...
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1answer
1k views

Predicting New Data with Naive Bayes

Say I had the following training set for a Naive Bayes algorithm. ...
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1answer
259 views

Spark 1.5.1: Train many binary classifiers, save them, then use them on new data

I have a DataFrame representing an annotated dataset with 300 labels. The DataFrame looks like follow (the first row is just to explain the columns): ...
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1answer
670 views

SPARK 1.5.1: Convert multi-labeled data into binary vector

I am using SPARK 1.5.1, and I have DataFrame that looks like follow: ...
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1answer
80 views

Is this a correct way improving a statistical model?

I am building a fair amount of statistical models - text classifiers and sequence taggers. The statistical models are linear in features - Logistic Regression and linear chain first order CRF. The ...
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1answer
2k views

What is the difference between concept learning and classification?

I've recently read about concept learning in a machine learning class. They defined a concept as (translated from German): Concept: Describes a subset of objects or events defined on a ...
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2answers
110 views

Classification when one class is other

I am working on a litigation support application using the Enron corpus, which contains about 600,000 unique text documents. In litigation, one is often concerned with whether a document is ...
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1answer
215 views

Does importance of SVM parameters vary for subsample of data?

I'm training a support vector machine classifier (SVM) on 100.000 observations. I'd like to try different parameter combinations (including kernel types) using cross-validation. However, it is ...
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2answers
3k views

Can HMM be used as a binary classifier?

I have some time-series data, which I need to use to predict a binary label for a given time-stamp. I was initially doing it using a Logistic Regression Model but I later figured that a time-series ...
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3answers
7k views

Appropriate algorithm for string (not document) classification?

I am trying to classify a large-ish number of small strings (millions) into about 10 disjunct categories. Examples of classes and strings for each class include: ...
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1answer
489 views

One multilabel classifier or one for each type of label?

Let's say I need to classify addresses with scikit-learn, so if I want my classifier to be able to classify addresses by the street name, and post/zip code, should I do a OneVsRest classifier, or ...
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1answer
1k views

Time dependent Classification problem

I am trying to solve a decision making problem. In it, information evolves and increases with time for each event observed, and the history of the event may be useful. The problem is as follows: in ...
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3answers
1k views

Using Machine Learning to Predict Musical Scales

It's possible to use Machine Learning techniques to cluster songs into musical-scale groups? I mean: "this song was written in C"... or "this song was written in Am" etc. I made a fast search about ...
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2answers
192 views

Reason behind choosing Neural Network for classification

Given a two class multi dimensional classification problem, what reason would you give to choose Artificial Neural Network for carrying out the classification instead of Support Vector Machine or ...
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2answers
188 views

Why would removing a variable in adaboost decrease error rate?

I was trying to classify an outcome on some data using adaboost (the ada package in R) and I was playing around with the training data set of descriptors when I realized that removing a column in the ...
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2answers
154 views

Neural network, Support Vector Machine or something else to classify into 7 groups

I'm an experienced developer but I'm only starting to discover data science. I have a data set consisting of 62 parameters for each row and each row in that data set belongs to one of 7 groups (...
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2answers
923 views

Use the output of 2 hidden neurons in the last hidden layer of a NN to visualize the result of a 4-class classification task

I am working on a 4-class classification task using an Artificial Neural Network. My aim is to visualize how well those 4 classes can be separated, moreover how consistent the data coming from each ...
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2answers
724 views

Classification of vector sequences

My dataset is comprised of vector sequences. Each vector has 50 real-valued dimensions. The number of vectors in a sequence range from 3-5 to 10-15. In other words, the length of a sequence is not ...
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2answers
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Voting combined results from different classifiers gave bad accuracy

I used following classifiers along with their accuracies: Random forest - 85 % SVM - 78 % Adaboost - 82% Logistic regression - 80% When I used voting from above classifiers for final classification, ...
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1answer
153 views

Behaviour of Learning Algorithms on Random Data

Suppose we collect data for 100,000 tosses of a fair coin and record "Heads" or "Tails" as the value for the attribute outcome and also record the time, temprature and other irrelevant attributes. We ...
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3answers
6k views

One Hot encoding for large number of values

How do we use one hot encoding if the number of values which a categorical variable can take is large ? In my case it is 56 values. So as per usual method I would have to add 56 columns (56 binary ...
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5answers
3k views

Covariate shift detection

Is there any standard approach for detecting the covariate shift between the training and test data ? This would be useful to validate the assumption that covariate shift exists in my database which ...
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1answer
53 views

Which value of output should be taken in multiple sessions of training Neural Network

Suppose I am using Neural Network for a 2 class classification. After training the network with the training set, I want to predict the class label of a dataset with no class label. Now with ...
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2answers
2k views

Equipment failure prediction

I have a system that manages equipments. When these equipments are faulty, they will be serviced. Imagine my dataset looks like this: ID Type # of times serviced ...
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1answer
154 views

Predictive models with class value belonging to a set of observations

I would like to know whether it's possible to build a predictive model where I could define a set of rows with their attributes, and a class belonging to that set of rows, instead of having the ...
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2answers
1k views

Difference between training and test data distributions

A basic assumption in machine learning is that training and test data are drawn from the same population, and thus follow the same distribution. But, in practice, this is highly unlikely. Covariate ...
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1answer
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what is nn.index mean in KNN output

I am getting attr(, "nn.index") as part of my KNN output in R. What is meant by that and how is this value getting calculated? ...
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3answers
786 views

How to train a Text Based data for a Machine Learning problem?

I am working on a project for displaying products to customer by context, based on a search query. For example, I don't want customers to have to enter a specific product name, instead searching based ...
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1answer
801 views

Error Analysis for misclassification of text documents

I am working on a text classification work. The purpose of this work is to classify whether a particular document belong to class A or Class B. I used KNN algorithm and i am able to get some decent ...
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1answer
94 views

Clustering the data if some values in each vector is not applicable

I have four different categories which the number of variables in each category is 7, 3, 8, and 9 (in total 27). The value of each variable changes from 1 to 5 but some of the variables were not ...
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1answer
192 views

Clustering large number of strings based on tags

I have string representations of text written by users in the form of parts of speech tags like so: $NNDN,OVDANPN,PNVRV,^^V,^^!$^OV and ...

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