The tag has no wiki summary.

learn more… | top users | synonyms

0
votes
0answers
18 views

Popular implementations of one vs all logistic regression for mutiple classes in R

Is there any popular implementation of logistic regression in R that defaults to using a one vs all approach for a categorical dependent variable with more than two classes? I have specific reasons to ...
0
votes
0answers
5 views

Precision of an incomplete classifier

Given a testing set of nodes which can be either +,-, or 0, I use an incomplete classifier which allows me to predict if a node is +, -, 0, not +, not -, or not 0, and sometimes it cannot predict ...
1
vote
2answers
37 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 ...
0
votes
0answers
5 views

How to extract the weight and bias in libsvm?

I want to extract the weight and the bias for my dataset which has two columns and more than 3000 rows. Also I want to draw a line by this equation: y = w.x + b where w is the weight, x is the data ...
1
vote
1answer
34 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 ...
0
votes
0answers
19 views

Implementing MMAC algorithm

I was reading a paper by Fadi A. Thabtah and et al., "MMAC: A New Multi-class, Multi-label Associative Classification Approach". I was trying to implement their MMAC algorithm. In MMAC algorithm that ...
0
votes
0answers
25 views

Significance test for multiclass classifier

In a multiclass classification problem, I want to measure the significance of my classifier against the null hypothesis (in this case, chance level). In this paper, in section 3.4, for a binary ...
1
vote
1answer
27 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
125 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
38 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 ...
2
votes
1answer
55 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
38 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
38 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
57 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 ...
2
votes
2answers
86 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 ...
0
votes
0answers
45 views

Accuracy vs F1 Measure in Multilabel Classification

I'd like to evaluate a multilabel classification algorithms and I was thinking of using both Accuracy and F1-Measure with: ...
1
vote
1answer
85 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
104 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 ...
0
votes
1answer
40 views

Transform multiclass classification to binary - benefits?

I have 400 instances which must be categorized into 4 classes. Using WEKA, I tried out a couple of multiclass classifiers like J48 and Random Forests, but never made it above Kappa 0.6 and ~65% ...
0
votes
0answers
96 views

SVM: plot multi dimensional data when implementing multiclass one-vs-all or one -vs one?

I have split the multi class svm to several binary classifications and obtained the individual predictions. My predicted labels are saved in a matrix 'predicted_vals' with each row containing ...
0
votes
0answers
183 views

Divison of multi class into binary class using libsvm (not classification)

I am working on multi class imbalance data.I want to divide my classes based on one verus one method and then perform sampling techinque How can I do that I just want to divide the classes not ...
3
votes
2answers
137 views

Machine learning for multi-level response

I have a dataset with ~90000 observations and less than 10 features (all continuous). The problem is that the response variable has ~300 categories. Currently I would try to fit a multinomial linear ...
4
votes
1answer
1k views

How to use scikit-learn's cross validation functions on multi-label classifiers

I'm testing different classifiers on a data set where there are 5 classes and each instance can belong to one or more of these classes, so I'm using scikit-learn's multi-label classifiers, ...
0
votes
1answer
127 views

How to improve classification performance based on multiple known classification results

I am working on a classification problem, which may contains a unknown number of data classes, typically 5-50 classes in each sample. I had several classification algorithms, each gives me a ...
2
votes
1answer
129 views

Hierarchical classification where leaf nodes in a tree are at no particular level

I have a set of hierarchical classes (ex. "object/architecture/building/residential building/house/farmhouse"), and I build a tree where each node is a classifier. However, the appropriate class for a ...
5
votes
2answers
222 views

How can a multiclass perceptron work?

I don't have any background in math, but I understand how the simple Perceptron works and I think I grasp the concept of a hyperplane (I imagine it geometrically as a plane in 3D space which seperates ...
0
votes
2answers
1k views

libSVM - probability estimates in multi-class problems

I am using libSVM for classification on a 3-class dataset. Using the option "-b 1" - for getting probability estimates for prediction - gives me surprising results. I am reproducing the issue with a ...
3
votes
2answers
129 views

Named entity recognition and class imbalance

I have implemented Maximum-entropy Markov model (MEMM) for the Named entity recognition (NER) problem. I have four classes: geographical, people, material (book titles etc) and other. Class ...
0
votes
0answers
51 views

Measures of diversity in continuous, multi-class classification learning problems

I'm training an ensemble of classifiers for a mutli-class problem. I want to measure pairwise diversity between a two classifiers' predictions. However, my classes are not categorical or binary, ...
2
votes
0answers
114 views

Maximum number of classes for RandomForest multiclass estimation

I have researched the internet|literature a lot on multiclass prediction to find out what is a realistic limit for the number of classes that can successfully be used for estimation when using a ...
4
votes
1answer
251 views

Confusion matrices with percentages rather than number of instances?

Most of the confusion matrices I've seen contain the number of instances in each cell. Isn't a confusion matrix with the percentage of instances in each cell easier to read? Is this approach wrong or ...
3
votes
0answers
112 views

binomial test for testing significance of classification very sensitive to hits count

I'm doing a multi-class classification task and I wonder if I'm doing the binomial test correctly since it is very sensitive to the count of correctly classified trials (hits count). Say, there are ...
13
votes
3answers
6k views

How to calculate precision and recall for multiclass classification using confusion matrix?

I wonder how to compute precision and recall using a confusion matrix for a multi-class classification problem. In specific, one observation can only be assigned with most probable class / label. I ...
3
votes
0answers
130 views

Reasons for transforming multiple class classification problem into a set of binary sub-problems?

Does anyone know of a good reference that list the reasons for transforming multiple class classification problem into a set of binary sub-problems? In response to comment: One reason to transform a ...
1
vote
0answers
72 views

Choosing a multiclass strategy

What would be the best approach to choosing the multi-class strategy (MSVM, OVA, ECOC) for classifying a large number of classes with limited examples of each class? Another two factors that define ...
2
votes
0answers
282 views

Calibrating multiple binary SVM classifiers for one-vs-all multi-class classification

I'm classifying text using the one-vs-all approach. There are three classes. I've trained 3 different binary SVM classifiers using 10-fold cross-validation. The accuracy of the binary classifiers ...
9
votes
2answers
671 views

How to determine the quality of a multiclass classifier

Given a dataset with instances $x_i$ together with $N$ classes where every instance $x_i$ belongs exactly to one class $y_i$ a multiclass classifier After the training and testing I basically have ...
9
votes
1answer
285 views

How to handle the difference between the distribution of the test set and the training set?

I think one basic assumption of machine learning or parameter estimation is that the unseen data come from the same distribution as the training set. However, in some practical cases, the distribution ...
0
votes
0answers
25 views

What is the multiclass loss used in kaggles for measure performance?

I searched on Internet but cannot find any source about this. What is multiclass loss and what kind of metric is it? If someone can enlighten me, it will be appreciated.
3
votes
0answers
94 views

Hierarchical decomposition of an imbalanced multiclass classification problem

I have a heavily imbalanced multiclass text classification problem: one class is very probable a priori (P), while the remaining four ones are about equally ...
0
votes
1answer
139 views

How do I do multiscale HMM classification?

I'm using hidden Markov models to classify some accelerometer data. I take the Fourier transform of the raw data at a given window length, and then train an HMM for each class, and every test instance ...
0
votes
1answer
536 views

R one vs all classification example code [closed]

I'm trying to build a one vs all multi-class classifier in R and my results are pretty poor. I'm curious if anyone can suggest a piece of example code somewhere on the internet. I'm trying to ...
1
vote
0answers
601 views

Combine MultiClassClassifier and MetaCost in WEKA and make cost matrices for each binary classifier

Ok, I have a classification problem in which i need to classify instances into one of 5 classes. The class distribution of the classes is imbalanced however. These are the frequencies of instances ...
5
votes
3answers
543 views

Suitable number of classes for SVM in text categorization

I'm doing text categorization with R and SVM in the package e1071. I have around 30000 text files for training, and 10000 for test. The goal is to hierarchically categorize these files. For example, I ...
1
vote
0answers
141 views

Binary Classification of Multiple Groups

I've ran across a type of classification problem that I don't think fits into the traditional multi-class framework. Just wanted to run it across you guys to see if you had any ideas. So Lets say we ...
4
votes
0answers
136 views

Number of states and symbols in multi class Hidden Markov Model classifier

I'm designing a multi class classifier (for 4 classes) using Discrete HMMs with States N and Symbols M for each of the HMM. However, I found that recognition performance(i.e highest log likelihood) ...
4
votes
2answers
290 views

Predicting multiple targets or classes?

Suppose I am building a predictive model where I am trying to predict multiple events (for instance, both the roll of a die and the toss of a coin). Most algorithms that I am familiar with work with ...
24
votes
3answers
7k views

How to compute precision/recall for multiclass-multilabel classification?

I'm wondering how to calculate precision and recall measures for multiclass multilabel classification, i.e. classification where there are more than two labels, and where each instance can have ...
7
votes
3answers
4k views

Best way to perform multiclass SVM

I know that the SVM is a binary classifier. I would like to extend it to multi-class SVM. Which is the best, and maybe the easiest, way to perform it? code: in MATLAB ...
0
votes
2answers
562 views

Voting in Multi-Class SVM [duplicate]

I am currently trying to classify 6 class of facial expression using SVM. I am using MATLAB and LIBSVM to do my classification. The problem i face is the pred label below produces 0 and 1. It treats ...