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

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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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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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46 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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48 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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53 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
25 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
106 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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22 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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1answer
16 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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1answer
44 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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26 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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33 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
18 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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15 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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10 views

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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45 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
117 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
40 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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41 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
33 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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2answers
64 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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68 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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69 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
44 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
128 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
25 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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87 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
86 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
44 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
167 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 ...
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287 views

Advantages of the softmax function in feedforward multi-class neural nets over logistic activation and one vs all approach

I am wondering if there is a benefit to the softmax function over an one-vs-all sigmoid activation function approach in feedforward neural networks for multi-class classification -- except for the ...
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1answer
101 views

How do I improve the accuracy of my supervised document classification model? [closed]

Given 1000 legal judgement documents, 900 of which are labeled, my task is to predict the label for the remaining 100 documents. The labeled documents belong to 41 different categories of Law, with ...
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2answers
268 views

Vowpal Wabbit: best strategy for short text data like titles & kewords

I am using Vowpal Wabbit 7.10.0 (VW) to learn and predict categories on text data. However, my text data for each record is not like an article or another decent-size text document, but rather a ...
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1answer
28 views

Is there ever any reason to discretise continuous ground truth if doing classification?

Is there a case where discretising continuous response improves classification performance? For example: A response variable is in the range 0 to 99. There are 10 classes defined by the following ...
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314 views

How to draw plot of the values of decision function of multi class svm versus another arbitrary values?

I am trying to draw a plot of the decision function ($f(x)=sign(wx+b)$ which can be obtain by fit$decision.values in R using the svm function of e1071 package) versus another arbitrary values. From ...
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50 views

How to create and format an image dataset from scratch for machine learning?

I've only worked with ML with .csv formats. I've worked with image formats too but only premade imagesets (MNIST,etc). If I were to create an imageset from scratch, how are the class labels typically ...
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2answers
205 views

Why do one-versus-all multi class SVMs need to be calibrated?

On the wiki page for multi-class support vector machines (https://en.wikipedia.org/wiki/Support_vector_machine#Multiclass_SVM) it states that "it is important that the output functions be calibrated ...
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166 views

Balancing Per-Class Accuracy of Multiclass Classifier

Suppose I have a multi-class classifier like Naive Bayes, k-Nearest Neighbors, Decision Trees, Random Forest, etc. The classifier maps a feature vector to (let's say) 3 classes: A, B, or C. My ...
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154 views

Confusion matrix with multi-class multi-label classification

Let's say I have three possible classes {'isCold' 'isWet' 'isSolid'} and my instances can belong to one or more of these classes. Ground Truth ice = {'isCold' 'isWet' 'isSolid'} water = {'isCold' ...
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64 views

Machine learning algorithm/approach advice for a particular problem - multiclass classification?

First real meaningful dip into machine learning here for a project, and I'd like to optimize my time spent by getting the algorithms of choice nailed properly from the outset. Straight up however I'm ...
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256 views

Logistic Regression one vs all probability scores calibration

I am applying concept detection on images. For each concept I am independently applying an one-vs-all Logistic Regression instance with its own training examples. Given an image, I want, given the ...
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24 views

Measure performance of a multiples classifier that is a combination of binary support vector machines

I am comparing the performance of multiple schemes to combine binary SVMs into one multiples classifier. I was hoping to use the cross entropy, however I cannot figure out how to apply it. For ...
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172 views

Negative samples on multiclass neural network training

I want to train a deep neural network to classify images. In every implementation I have seen, multiclass training uses only the positive examples for each class. Is there any way to utilize ...
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1answer
74 views

Which one to choose and when? One-v/s-One and One-v/s-All classification for multi-class classification

In case of multi class classification task, how do we decide which among the two options viz. one-v/s-all and one-v/s-one do we choose for model building? Is there some criterion based on which we ...
2
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2answers
229 views

How can I derive confidence intervals from the confusion matrix for a classifier?

I have am using k-fold cross validation to generate a confusion matrix for a classifier. I need to calculate 95% confidence intervals for the number of times each class is predicted when run against a ...
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1answer
77 views

is negative log loss affected by oversampling?

I'm working on a multiclass classification problem where negative log loss is the evaluation metric. My initial train set and my static test set have similar class distribution and my validation (20% ...
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1answer
52 views

Suggestion for method/framework to use for short string classification with “complex” ouput

What I am trying to do : I have short text strings (max 128 total chars in length) which I would like to classify (or use for prediction) as belonging to a particular type of output (more on the ...
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79 views

VW multiclass classification

I am new to vw and trying to do a multiclass text classification with 18 classes. features are unigram, bigram and trigrams. Total features are around 1.4 million Total training examples 35 million ...