The multi-class tag has no wiki summary.
2
votes
0answers
31 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 ...
1
vote
0answers
19 views
Tolerating labeling errors in classification
Suppose I have a set of labelled instances L, I apply a supervised learning (any classifier) on them to learn a model for classification. Now suppose that I want to add some new instances to L, but ...
2
votes
1answer
33 views
Confusion matrixes with percentages rather than number of instances?
Most of the confusion matrices I've seen contains 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
64 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 ...
0
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0answers
82 views
How to compute precision for a multiclass problem?
I have a question about calculating precision on a multiclass problem. If the true positives of some actual class is 0, and its false negatives is also 0, then how to calculate its recall? In this ...
4
votes
2answers
564 views
how to calculate precision and recall for multiclass classification using confusion matrix?
all, I wonder how to compute the precision and recall using confusion matrix for multi-class classification problem. In specific, one data can only be assigned with most probable class/label.
I like ...
3
votes
0answers
58 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
51 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 ...
1
vote
0answers
141 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 ...
7
votes
2answers
189 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 ...
8
votes
1answer
129 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
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0answers
19 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.
2
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0answers
62 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
96 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
306 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
329 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
360 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
113 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 ...
3
votes
0answers
96 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
191 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 ...
18
votes
3answers
5k 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 ...
4
votes
3answers
2k views
Best way to perform multiclass SVM
For the past two days, i have been trying to perform multiclass svm. I know that the SVM is actually a binary classifier. I would like to extend it to multi-class SVM. Which is the best way and maybe ...
1
vote
1answer
299 views
Voting in Multi-Class SVM
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 ...
8
votes
1answer
626 views
Extending 2-class models to multi-class problems
This paper on Adaboost gives some suggestions and code (page 17) for extending 2-class models to K-class problems. I would like to generalize this code, such that I can easily plug in different ...
