Multiclass classification is a classification task in which there are more than two classes. It is also called multinomial classification.

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Multi-class SVM Calibration

Say we have multiple SVMs used in a one-vs-all approach, such that classes a, b, c correspond to 3 SVMs trained positively on the class and then negatively on all ...
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Increasing the number of randomly chosen negative examples decreases the performance of the Classifier

Introduction I have a set of $k = 1000$ classes. Every class is composed of $1$ to $20,000$ examples. An example is represented by a tfidf vector of real numbers of dimension $160,000$. The tfidf ...
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35 views

Multiclass classification question

I am working on applying Random Forests to a multiclass classification problem, where I have a set of 11 predictor variables and a response that can take the values of "Yes", "No", and "Maybe". In my ...
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28 views

Can we compare classifier scores in one-vs-all/one-vs-many?

In a system where we perform multi-class classification via a one-vs-all technique, are two scores comparable? E.g.: If I have 0.5 and 0.6 on two different classifiers, is it possible to say that the ...
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51 views

One-vs-many/One-vs-all - what value to use as probability?

I have constructed SVMs to do a one-vs-many approach to classification. Let's say I have 3 classes and I train 3 SVMs in a one-vs-many format. This gives me 3 SVMs each trained positively on one of a ...
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7 views

Multi labels classification tools / algorithms that can support distributed computing

Currently I'm using mulan library, with random k labels method (in Java) for solving my multi labels classification problem. But I encountered a memory problem due to memory usage. My training file ...
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23 views

Why is my SVM multiclass classifier only correctly predicting a few classes?

I'm doing an online course to learn the basics of Machine Learning. This exercise is on how to use a SVM classifier with multiple classes. While the problem is specific to question 2 from this ...
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24 views

What are proper scoring and threshold selection rules for multiclassifiers?

I am using a neural network with 5 input neurons, 2 hidden layers of about 50 neurons in each layer, and 4 output neurons, trying to classify my 5-dimensional data into 4 different classes. ...
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1answer
20 views

Extracting weights from a classifier's posterior distribution

Given a classifier $C$ that gets text as an input and outputs a posterior distribution $p_1\dots p_n$ on $n$ possible topics. In other words, for each user post, I have a list of probabilities ...
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2answers
19 views

Quantify quality of multi label assignment

I am interested in quantifying how well a multi label assignment performs. E.g. given 3 coloured boxes red, green and blue, with 20 likewise coloured balls in each. A monkey is handed all the balls ...
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1answer
25 views

Multi-class classification easier than binary classification?

I have 10 different classes in my classification problem. Each class has about 200 instances, with more than 10.000 features. I performed the classification using Multinomial Bayes classification. ...
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36 views

True positive, false negative, true negative, false positive definitions for multiclass-multilabel classification?

I'm trying to apply some evaluation metrics to several clustering methods. I thought that I knew them basing on the multiclass confusion matrix, considering the rows as the actual classes and the ...
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23 views

Multiclass SVM result [closed]

I have a problem with multiclass SVM result. My classes are {-1,0,1} and my CVed precision is {0.2,0.8,0.8}, where contribute with -1 poor classification. If I change classnames to {6,5,4} my CVed ...
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16 views

Multiclass classification with large number of classes but for each user the set of target classes is known

I'm new here but I'm familiar with some machine learning theory (took some courses in school) and my question is more about how to apply ML in a practical setting. I have this project where I'm ...
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1answer
28 views

Feature selection based on mean, standard deviation and mean absolute deviation

Suppose we have a large dataset (~ 60000 entries, 58 variables, 4 class labels). For each variable mean, standard deviation and mean absolute deviation are calculated - separately for every class ...
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16 views

Test equality of multiple proportions

Conciser a cross-tab like this (or equivalent just with different number of either classes or folds): ...
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7 views

Easy way to interpret an Evaluation a multi class model

I am working on training a classification model for 38 different classes. When i tried to evaluate it's performance by using Crosstable from Gmodels package, It was very hard to interpret, Any ...
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17 views

Multi-class classification with categorical predictor variables

I want to apply the stacking technique but I don't know how meta-classifier I should use. The output of 3 base classifiers are 3 classes (A, B and C), and the response is already the classes A, B and ...
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28 views

handle unbalanced data in multi-class

I have three classes A,B,C. They are different in their feature values. Another class D is the one I want to distinguish from A,B,C. From my perspective, I can treat A,B,C as one class (let's call it ...
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23 views

Is it acceptable to use class probabilities as weights for a weighted average when the bins are numbers 1 to 5?

I have a Multi Class SVM that can predict what class some observation belongs to. There are 5 classes. They are trained for observation that scored 1 to 5. I want the MC-SVM to predict a class for ...
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91 views

Matthews correlation coefficient with multi-class

Matthews correlation coefficient ($\textrm{MCC}$) is a measurement to measure the quality of a binary classification ([Wikipedia][1]). $\textrm{MCC}$ formulation is given for binary classification ...
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58 views

Precision in unbalanced multi-class problem

I am dealing with a multi-class classification problem and I compute micro-averaged evaluation metrics (precision, recall and F-measure) by performing 10-fold cross validation. However, the fact that ...
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95 views

Multiclass vs. One-vs-All vs. One-vs-One classification

I am working on a classification problem with 7 classes. Is there any rationale to suspect that the best model might be found with a multiclass classifier, multiple one-vs-all classifiers, or even a ...
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1answer
34 views

how to make new class from the test data in machine learning

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
13 views

Normalizing document numbers for multiclass perceptron

If I have a multiclass perceptron that I'm using for document classification, and the dataset I'm using has different numbers of documents for each class, is there any normalization that has to be ...
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1answer
182 views

How to build a confusion matrix for a multiclass classifier?

I have a problem with 6 classes. So I build a multiclass classifier, as follows: for each class, I have one Logistic Regression classifier, using One vs. All, which means that I have 6 different ...
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34 views

Multi-class classification with ranking

I've got an interesting dataset for multi-class classification with ranking. The idea is to build $K$-class classifier respecting the ranking. The ranking information is given with the training set ...
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21 views

Mathematical definition of “confusable classes”

I have seen this term in this paper http://jmlr.org/papers/volume15/gupta14a/gupta14a.pdf and I was wondering if there was a formal definition (I have an intuitive understanding, but something more ...
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56 views

Confidence metric for a single prediction in multiclass classification?

Are there any particular methods (Naive Bayes, SVM, RF, etc) that can provide some estimate of 'confidence' along with the class prediction for a test feature set in which the true class is ...
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29 views

Under what conditions decreasing number of classes increases/decreases precision of multi-class SVM?

I have a multi-class classification problem that is being solved using SVM. I have a set of ground truth data with K different mutually exclusive classes. This is ...
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40 views

What are the problems of these decision trees outputs?

I have a report that using two structures of decision trees for a multi-class (4-classes) classification problem with 7 inputs. First output is for ...
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1answer
21 views

Herarchical class classifier with default parent class labelling

I have a hierarchy of classes for which I need to train a classifier which will assign the lowest level class in the hierarchy and default to an upper level class , is this possible to do with scikit ...
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16 views

Does Multiclass prediction gives alternate classes in vowpal wabbit?

Does the multiclass task in vowpal wabbit allow to get a list of probable classes for a featureset. i.e instead of getting only the predicted label for a featureset , it is required that a list of ...
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Determine if class is harder to define or not meaningfully distinct?

Say you want to improve a model that doesn't meet your desired standards. In order to do this, you create a method that identifies candidate class labels that are interpreted to be either: (i) harder ...
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14 views

Using a classifier's test error as a model evaluation metric for another model

I have a multi-class multi-label (MCML) dataset, built from a model I do not trust (assume I am right for distrusting it). Say I have 1000 patients with 14 feature scores, and 5 possible target labels ...
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89 views

Multi-class classifier with rejection option in Sklearn

I am working in a 3D gesture recognition project with kinect. So far, I have trained classifiers with 5 gestures. Still need to implement for real time recognition. The thing is this. Most of the ...
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2answers
136 views

Hierarchical Multi-label Classification

I would like to make a classifier, where I can classify individuals from one hand, and from the other hand, understanding the data better, meaning figuring out which feature, is the most contributing. ...
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1answer
47 views

Detect multiple classes in an image?

I have a deep neural network trained with data of different kinds of fruits (apples, oranges, guava, pear, etc.). In my testing data, I have multiple fruits in the same image. For example, an image ...
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61 views

Micro vs weighted F1 score

In a multi-label or multi-class classification setting, when choosing between a micro or a weighted F1 score, what shall I take into account? The main upside of choosing macro is that one gets a ...
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1answer
38 views

Is there any clearer term than multiclass classification?

Multiclass classification is the problem of classifying instances into one of the more than two classes. However, the prefix multi means "more than one" (as in multi-label classification: if one ...
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97 views

Evaluation of binary approach to one vs all multi-class classification

I'm working on a multi-class problem which I have redefined as a series of binary problems (i.e. a one vs all classification problem). However, each observation can belong to more than one class. For ...
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76 views

LDA scores too big

I'm trying to do dimensionality reduction with linear discriminant analysis (LDA) in MATLAB. I'm using this code to calculate the coefficients. But I'm confused whether (and when) should I center the ...
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90 views

Naive Bayes - Good for Binary Data?

I have 92 observations with 92 variables. Every observation is a binary outcome (0=no, 1=yes), indicating if that observation co-occurs with a given feature in the feature set. I have 18 classes which ...
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2answers
47 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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1answer
195 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 ...
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1answer
26 views

Quadratic error for multi-class classification

I'm trying to train a neural network to classify handwritten inputs into 10 categories, each for one digit (1,...,9,0). I represent the output of an example using a 10-dimensional vector. Digit 5, for ...
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101 views

Problem with backpropagation algorithm for Feedforward Neural Networks

The objective When trying to exercise my knowledge of Feedforward Neural Networks, I started implementing one. The result is here. The final goal is to predict some handwritten digits data I have. ...
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1answer
114 views

What is the difference between Multitask and Multiclass learning

Consider a image labeling problem, where I need to assign one or more labels to an image. The possible labels are human, moving ...
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1answer
62 views

Are the total false positives and false negatives of a large confusion matrix equal?

I have a confusion matrix which is 20x20 that is the product of a random forest classification of ~20k instances. Each of these instances was put into a specific class where rows are actual class and ...
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1answer
227 views

How to do one-vs-one classification for logistic regression?

I have a dataset with 4 clases and I want to apply logistic regression with one-vs-one classification. So, first I train for each pair of classes a logistic regression classifier (i.e. calculate the ...