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

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How to calculate multi-class prediction probabilities using One vs All and One vs One classifiers

To be specific, let's consider Support Vector Machines. In the 1 vs all case, one has $n$ binary classifiers where $n$ is the number of classes. In each classifier one has two labels 0, 1 and for a ...
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32 views

Which are the suitable classification algorithms when the number of categories are more than 1000

Combination of categories is not possible as each class is a distinct brand. One similar challenge was classifying objects using images (link below) but I could get any specific direction from few ...
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13 views

How to perform outlier detection in a multi class dataset?

I have a dataset with 40 class labels and outlier data in it. The dataset is a high dimensional one with 1500 features. I am in need of building a model to detect the outliers in the dataset, using ...
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25 views

Spark K fold Cross validation [closed]

I’m having some trouble understanding Spark’s cross validation. Any example I have seen uses it for parameter tuning, but I assumed that it would just do regular K-fold cross validation as well? What ...
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20 views

How to operate on a count dataset (positive whole numbers with a lot of zeros) using neural networks for classification?

So i have some dataset, which is basically a count dataset. I have my own code for the classification using neural networks. Turns out that the data does not have a lot of correlation so accuracies as ...
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Cross-validation on XGBClassifier for multiclass classification in python [migrated]

I'm trying to perform cross-validation on a XGBClassifier for a multi-class classification problem using the following code adapted from http://www.analyticsvidhya.com/blog/2016/03/complete-guide-...
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53 views

MNIST Softmax regression hitting a wall at 70% accuracy

I've implemented a Softmax regression algorithm in java as part of an Android machine learning program. However, no matter how long I let it run for, the accuracy gets to about 70.5% and then plateaus ...
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36 views

Help interpreting formula for multi-class hinge loss

As I'm reading from wikipedia, and this Cross Validated question: Gradient for hinge loss multiclass, the gradient value for a training feature set is somewhat straightforward. However if I'm ...
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multiclass models: probabilities to predictions with asymmetric distribution of class

I'm dealing with the following problem: I have a multiclass variable, y, with let's say 7 classes. The 7 classes are not evenly distributed, some are way more likely to occur than others. Let's say ...
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15 views

Evaluating Multiclass Classification Predictions factoring distance between classes

So I have a classification task which predicts a given input as one of 5 classes. Regular error metrics like precision and recall are easy to compute for each class but is it possible to factor the ...
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20 views

How to include cost-sensitivity in weight update rule for multiclass logistic regression?

I have the following weight update rule for a multiclass (with k classes) logistic regression with l2 regularization optimized using stochastic gradient descent: $$ w_i = w_i - \eta * softmax_i(...
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How to represent no-detection in a confusion matrix

So let's say we have a multi-class classification problem and we want to represent the outcomes as confusion matrix. All the examples I'm finding on the web asume that all the elements are detected. I ...
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22 views

MCC or F-measure, which measure is the best to represent multi-class confusion matrix

I'm building a classifier of multi-class problem. In my context I have to classify vehicles into five categories: cars, vans, trucks, buses and motorcycles. I would like to use some measure to ...
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6 views

How to calibrate scored probabilities to counter over prediction of events in ranked deciles?

I have a dataset that has 3 class probabilites w.r.t. a reference class. Using neural network. I scored the dataset and getting over prediction of events when I rank order the scored probabilities, ...
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17 views

Difference between multinomial and one vs rest schemes in logistic regression

I am dealing with multiclass classification problem where I have 10 classes to predict. I came across Logistic regression model in scikit-learn which can be applied to multiclass settings as well. The ...
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1answer
35 views

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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3answers
45 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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2answers
44 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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86 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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13 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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31 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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36 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. Currently,...
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23 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 $\{p_i\...
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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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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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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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30 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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25 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
45 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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20 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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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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24 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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29 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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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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130 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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68 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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125 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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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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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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252 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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48 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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22 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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63 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 unobserved?...
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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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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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18 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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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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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 ...