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0
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1answer
20 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 ...
0
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0answers
18 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 ...
0
votes
1answer
24 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 ...
1
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0answers
21 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 ...
1
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1answer
20 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 ...
1
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0answers
71 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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0answers
14 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 ...
3
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2answers
99 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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0answers
58 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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0answers
54 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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0answers
47 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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0answers
99 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 ...
1
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0answers
16 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 ...
1
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0answers
73 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 ...
0
votes
1answer
36 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
votes
1answer
98 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 ...
0
votes
1answer
40 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% ...
0
votes
1answer
34 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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0answers
61 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 ...
2
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2answers
429 views

Output of Scikit SVM in multiclass classification always gives same label

I am currently using Scikit learn with the following code: ...
0
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0answers
21 views

Is it OK to resample data in one vs all multiclass classification?

I have a multiclass classification problem and decide to use one vs all logistic regression. Since some classes are very rare (pos vs neg is like 1:100), I plan to use some balancing strategy during ...
0
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0answers
17 views

Classification under uncertainty in observations

I am tackling a multiclass classification problem where the values of the independent variables are not known with certainty. Instead, each observation is represented by a multivariate Gaussian pdf ...
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0answers
12 views

Do you know about SVM plait?

I need to know about how I can applied many single SVMs? because I have read about SVM plait that does this kind of classifications that is using many single SVMs to improve the classification process ...
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0answers
65 views

LibSVM totalSV for multiclass

I am performing classification of K=9 classes using linear SVM with libSVM (MATLAB warp) I am using 400 samples of data to perform the training and I'm getting: totalSV: 203 I know libSVM uses ...
1
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0answers
72 views

dealing with imbalanced data set in multiclass text classification

I need to build a text classification model. I have a labeled training set and my goal is to classify the new unlabeled text . My training set is composed on 6 categories, that are imbalanced. The ...
0
votes
1answer
144 views

Suggestions needed about classifier fusion

I'm working on a classification problem which involves two classifier to observe a single event. I'm providing a high level description of the problem without going into the technical details (the ...
1
vote
0answers
16 views

Multiclass target detection : N X (1 vs all) or 1 X (N vs all) ?

I am doing a multiclass classification using neural networks. say I have 10 target classes and one null (non-of-the-above-targets). is it better that I train a neural network separately for each ...
0
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0answers
18 views

Assign attributes / categories to users based on their activity / likes

I have a very practical classification problem for which I need some help. I have a database of users along with their activity / likes for a number of car models. I also have the category each of ...
0
votes
1answer
777 views

Multi-class logarithmic loss function per class

In a multi-classification problem, we define the logarithmic loss function $F$ in terms of the logarithmic loss function per label $F_i$ as: $$ F = -\frac{1}{N}\sum_{i}^{N}\sum_{j}^{M}y_{ij} \cdot ...
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0answers
5 views

How can I counteract the effect of a degenerate classifier in an OVA Model?

Suppose I build a OVA classification model for classification with more than 2 possible classes (a model of sub-models, where each submodel predicts the probability of a data point belonging in a ...
0
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0answers
15 views

Implementation of batch Hieron

I would like to implement the Hieron algorithm, which is described in the paper "Large Margin Hierarchical Classification". The basic online Hieron is specified in the paper, but I need the batch ...
0
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0answers
168 views

Multi-class AUC in Matlab

I would like to compute the area under the ROC-courve (AUC) metric for a classifier with multiple classes. Do you know (reliable) functions for Matlab that implement methods for that, like e.g. in ...
1
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0answers
26 views

Walking recognition

I have walking samples from 20 different people. My aim is to detect which walking samples are from which person. I'm trying to achieve this by extracting "walking cycles" from each person's dataset ...
1
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0answers
544 views

Logistic regression with multi-class features in R

I'm working with a data set like the following: X = ...
1
vote
1answer
264 views

Softmax regression or $K$ binary logistic regression

For a multi-class classification problem, we can use $K$ binary logistic classifiers, or one softmax regression classifier, so how to make the choice between the two? IMHO, the $K$ binary logistic ...
2
votes
1answer
314 views

What is the difference between a multi-label and a multi-class classification?

What is the difference between multi-label classification and multiclass classfication. Speficially, what is the difference between a label and a class? Please provide a clear example. "Multiclass ...
6
votes
1answer
1k views

How to get confidence on classification predictions with multi-class Vowpal Wabbit

I have a classification problem in which I'm using the --ect option for the multi-class algorithm. The output of the classifier is something as follows: ...
1
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0answers
99 views

What should I use - Multi label classification or Multi class classification? [duplicate]

In my dataset, I have 2 labels, positive and negative. Most samples belong to only one class, either positive or negative. A small fraction of samples take both labels i.e. both positive and negative. ...
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2answers
86 views

Can a nuisance multi-class classifier do better than binary classifier?

This is rather a theoretical question in order to save the trouble in trying to do empirical testing and is part of a bet, so I hope I am right... Say there are M classes in the data BUT you want to ...
2
votes
1answer
318 views

What is the difference between accuracy and agreement?

According to Manning et al. (p. 155) accuracy is the sum of the diagonal in the confusion matrix divided by the sum of all items. On the other hand, following Artstein and Poesio (p . 558) precisely ...
1
vote
1answer
52 views

Limit multiclassification SVM - ANN

I have some questions on the limits of SVM and ANN for multiclass problem. I know about "one vs all" and "all vs all" strategies but I only want to know the limit of a unique SVM and ANN. Is there a ...
1
vote
1answer
155 views

Linear statistical model with two-class variables

Suppose I have a set of (discrete) variables, say $X_1,\dots,X_n$. Each $i$ belongs to either class A or class B. When it belongs to A the contribution is $Y_{A,i}f(X_i)$, and when it belongs to B the ...
0
votes
0answers
54 views

Learning from distance matrices

I have a task to build multi-task classification model based on distance (similarity) matrix only. They are already precalculated and no changes here can be applied. Can you, please, recommend me ...
3
votes
1answer
94 views

libsvm_linear kernel_increasing C value

I'm using libsvm in C-SVC mode (-s= 0) with linear kernel (-t= 0), and I'm required to train multiple SVMs( I have four classes). My training and test sets have the same number of instances and ...
2
votes
1answer
753 views

Using predict_proba with sklearn's multiclass SVC

I'm using python's sklearn for multi-class classification (SVC) When using the predict method, i get very high scores with my dataset, However, I want to plot ROC curves for each of my classes. That ...
0
votes
0answers
71 views

Decompose LibSVM model into binary classifiers

I have a multi-class .model trained with LibSVM. Is there a way to decompose this model into different binary .model files? For example, if I have a .model trained for $n$ classes, I would like to ...
1
vote
3answers
69 views

“finely” labeled classification problem

I came across a kind of classification problem. Suppose I have a dataset with labels, where each label is one of a1, a2, a3, b1, and b2. I want to make a classifier that estimates "coarse" label, a ...
3
votes
2answers
191 views

Good strategy for multiclass classification (when there is hierarchical class structure )

Combining binary classifiers, I want to solve multi-class classification problem in the following setting. Suppose there is a dataset and each data is in one of four classes: A1, A2, B1 and B2. A1 and ...
2
votes
1answer
246 views

Area Under ROC Curve for Multiple Classes

I am working with a highly class-skewed three class classification problem. The class percentages are A = 1.8%, B = 17.5% and C = 80.7%. According to this paper, the following definition of ...
1
vote
1answer
236 views

Unassigned classes in Multiclass SVM with One vs All Approach

How do you handle unassigned classes in multiclass support vector machines (multiclass SVM) with the One vs All approach? Lets say my training data has three classes A, B, and C. I use 3 SVM ...