Questions tagged [multi-class]

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

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Improving accuracy of multi-class text classifier

I am trying to build a text classifier with 4 highly imbalanced classes. Data has around 4000 documents and highly sparse. I have used XGboost and few other algorithms.Highest accuracy is given by ...
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Hessian Matrix for MultiClass Softmax in Gradient Boosting (XGBoost): $2p_i(1-p_i)$

In the context of MultiClass Softmax, for a particular training instance, label and prediction $y, p \in \mathbb{R}^K$ (K categories). The hessian matrix for Multiclass SoftMax with K categories is a $...
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9 views

Performing classification when the potential options of classes are different for every data row/user

I have a problem that I am trying to solve using ML but am not able to determine techniques, hence asking for advice. Appreciate your urgent response! I have a dataset of several users. Each user has ...
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32 views

Comparing multiclass AUC between two classifiers trained on the same data

I have fit two different multiclass classifiers on the same data, one is a multinomial logistic regression the other one a KNN Classifier. Now I want to know which one has a better fit in general. I ...
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15 views

Unbalanced data set - how to optimize hyperparams via grid search?

I would like to optimize the hyperparameters C and Gamma of an SVC (SVM scikit-learn) by using grid search for an unbalanced data set. So far I have used class_weights='balanced' and selected the best ...
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How many data points per class is neccesary to train a multi-class deep learning model?

I have around 20,000 manually categorized texts into 500 classes. Around 150 of the classes have only one instance in the data. If I limit it to classes with at least 4 instances in the data, I get to ...
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19 views

How to maximize subset accuracy for multilabel multiclass image classification

I working on multi-label multi-class image classification. I am using TensorFlow. Currently I am using sigmoid on output layer with binary_crossentrpy. Model is ...
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43 views

Why not approach the Multi-Class Classification problem using Neural Networks as a model the same way it's approached with a Logistic Regression model

I can't seem to understand why when approaching a K-class classification problem using a Neural Network we take a different approach than any other classification model. I understand that in the ...
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55 views

Tuning threshold from multiclass ROC for Gradient Boosting Classifier?

I have created a ROC curve based on the output of a multiclass Gradient Boosting Classifier (See Figure below implemented from Yellowbrick ROCAUC: https://www.scikit-yb.org/en/latest/api/classifier/...
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How high is multiclass AUROC too high?

Whenever I get AUROC above 80% for a binary classification problem I do my best to check for leakage and overfitting - and usually my intuition is right, true AUROC is closer to the 70%-75% range. ...
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Passive Combination of two Classifiers at the level of Class Labels

I have three classifiers - 1. Vision based classifier trained to detect class labels such as pedestrian and cars 2. Radar based classifier to detect same class labels 3. Lidar based classifiers to ...
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42 views

Bayes Decision Theory With 3 Classes

I'm trying to create a Bayes classificator in 1 dimension with 3 classes. I have created the following graph, where you can see that from zero to $x_{bnd1}$ is the first area $R1$, then from $x_{bnd1}$...
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Why does the 'weighted' f1-score result in a score not between precision and recall?

On the F1 score sklearn page there's a section that explains each of the options for the average parameter. Under the weighted option, it says: "it can result in an F-score that is not between ...
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41 views

Loss function in Text Generation using word-level approach

I'm trying to solve a problem of sequence prediction, which is in similar in spirit to Text Generation. I've seen several tutorials addressing a word-level approach, such as this one, resulting in a ...
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533 views

Error while performing multiclass classification using Gridsearch CV

I am trying to solve a multiclass classification problem using SVC as the base estimator and GridSearchCV to tune my results. Mentioned below is the code and the error being received: ...
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37 views

Is skip-gram model of word embedding actually a multi-class task not a multi-label task, right?

So curious about this question, that I can't describe it in short. Please forgive me. Description: From multiclass and multilabel algorithms, we can get the definition of the multi-class and multi-...
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Log-likehood : ommited value

I searched the second form of the log-likelihood equation which appear in A Probabilistic Perspective of Kevin Murphy because I've tried to understand why $y_{ic}$ disappear in the second part of the ...
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Define Insurance Risk Score from Unsupervised Clustering + Supervised Classification using logits

I am trying to use a Neural Network to perform multiclass classification. The classes represent Insurance Risk Level. The most risky level is Level 1, the least risk corresponds to Level 10. The ...
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23 views

Is it wise to reduce the number of labels in a multi-class classification problem?

I'm working on a dataset which has 5 labels or the outcome, Y. I'm going to use ML model to predict the 5 labels. While doing the data analysis, I found that class1(60%), class2(39%),class3(0.33%), ...
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is that ok if we have just one intercept for one hyperplane in SVM?

I am doing classification and using SVM. I am trying to do that by myself not using library or ready function. I get the best result when I have 1 intercept for one hyperplane and no intercept for 2 ...
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Comparing multiclass LDA and logistic regression equations

I was told that LDA and logistic regression is the same, when we consider 2 class situation. That I can also confirm (I think), for LDA $$\log \frac{Pr(Y=1|X=x)}{Pr(Y=0|X=x)} \\ = \frac{f_1(x)\pi_1}{...
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What Multi-Class Text Classification alghoritm return few possible option?

I'm looking for some alghoritm to use for Multi-Class Text Classification and returns not only class with the highest possibility but a few ones. Its like with gensim Word2Vec: ...
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444 views

Calculate AUC using sensitivity and specificity values only

How to calculate AUC, if I have values of sensitivity and specificity for various threshold cutoffs? I have sensitivity and specificity values for 100 thresholds. ...
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1answer
129 views

Oversampling a multi-labeled data set

Given a data set where each individual data point can be assigned to more than 1 class (a multi-class, multi-label data set), are there any guidelines for calculating oversampling weights, i.e., the ...
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how to use RFB for primal svam model?

I know if we want to solve primal model of non-linear SVM, we have to generate new features. for example for kernel (1+xz)^2 for primal problem for any pair of features x1 and x2 we have to generate: ...
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73 views

Feature selection in multi class environment

I have a $\mathbb{R}^{10000 \times 25000}$ feature matrix (10000 observations and 25000 features). The observations come from 4 different classes, i.e. it is a multiclass classification problem. I ...
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188 views

Best model for multiclass classification

I have a dataset which consists of categorical predictors, and I hope I can classify them into 3 different classes. Instead of creating a "Black box" model, such as neural network and svm, I would ...
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38 views

Multi-output and multi-class classification?

I have a question regarding the following classification task. I guess that the forecasting problem can be seen as a multi-output and multi-class classification problem. But i am absolutly not sure. ...
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68 views

multiple measurements for classification; which one to choose?

There are five different classes (labels) where the new points have to be classified at. For each new point, five different measurements are conducted, resulting into similar although different values ...
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46 views

Permutation test for accuracy in multiclass discrimination

It is well known that to assess the significance (i.e. difference from chance) of the performance of a classification analysis one can use a permutation test. In a two-classes case, the procedure is ...
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17 views

does multicolinearity affect classification models? any type of classification models like SVM, ANN, Random Forest,etc

I have been working on a dataset with more than 50 variables and I know some of the variables are highly correlated(>0.8). so for my multi-class classification problem should I worry about ...
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Correlation of ulticlass classification results between multiple methods

I have a multiclass classification task and some methods for the task. Then, I want to analyze the classification results among the methods. I would give you an example. Task: Animal Classification (...
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48 views

Improveness given a certain AUPRC

I am training a machine learning model (Random Forest) for a multiclass problem (64 classes) in which most of them are highly imbalanced. That's why I am using mainly F1 score for checking the model's ...
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76 views

Sequence Classification Machine Learning Methods

I know that this question might have been asked before but I did not find any response so far. My problem is that I am doing Multi-class sequence classification with Stacked LSTM (3 layers) using ...
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Naive Bayes missclassification rate across classes

I have a dataset with income, age sex and education as categorical features. I used R to create a Naive Bayes classifier as follows: income ~ age + sex + education. I got the following a-priori and ...
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63 views

Is there any strategy for validating the result of a general comparison between several confusion matrices?

Disclaimer: Recently we have developed a python library named PyCM specialized for analyzing multi-class confusion matrices. A compare system has been added in <...
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257 views

Evaluating Unbalanced Multiclass Classifiers: Which Tests to Use? [closed]

I am looking for some comprehensive instructions and ideally out of the box solutions (ideally for python) for evaluating different classifiers (which are already trained) for a multiclass ...
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20 views

Are these Multi-label document classification experiment steps sensible?

I plan to filter an input document using 4 different labels. Just for an example, a document discussing about movie summary needs to be labeled with 4 labels (Romance, Drama, Fiction, Hollywood). ...
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193 views

Improving Average F1 Score for Multiclass Classification

I'm trying to do a multiclass classification with h2o in R. I stacked a model with a RF, GBM and deeplearning. The accuracy is ok (~0.81), but the average F1 score is bad because class B has a very ...
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108 views

Is it possible to calculate the ROC_AUC score for a class in a multiclass problem that is not in the predicted array?

I was working on calculating the auc score for a multiclass problem and came across this problem. Suppose I have a data set with three classes [0,1,2] My test set is like this [0,1,2,0,0,2] My ...
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What measures of an ML algorithm's 'accuracy' are mostly consistent as the number of classes to predict into varies?

For a research project, I've got a bunch (N=507) of 20-second VR tracking data clips (6DOF x head and hands), each from a different participant. My goal is to predict the participant using a small ...
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512 views

SMOTE sampling for multi-class data

I have a classification problem with 4 distinct classes, but imbalanced data. ...
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11 views

Multiclass classification- dealing with clusters within classes?

I'm currently dealing with a problem where I'm trying to predict how much a value x will change over time given input variables and am bucketing this change into separate classes (ie -100 to -50%, -50%...
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37 views

Multiclass classifier with undefined prediction, how to calculate metrices

I build a multiclass classifier. I want the classifier to predict a few samples with little false positives, rather then many samples with lots of false positives. Therefore I want to choose a ...
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24 views

How to calculate precision-recall curve for multiple binary classifier for multiple classes

I am using autoencoder based multiple binary classifier for text regeneration each trained on data related to multiple classes. In other words, each classifier is trained to classify only one class. I ...
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26 views

Multiclass classification with a balanced dataset and one high-priority label

I have a balanced dataset for a multi-class classification problem with one high-priority label (this ought to be classified properly at all costs). How do I go about creating a workflow for this ...
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54 views

Is Multi-output Multi-Label classification possible for this merging problem?

I have programmed a game called cell wars where cells can capture other cells via merging. The image below shows the same board before merging (top) and after merging (below). Basically, overlapping ...
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Identifying Misclassifications

Let's say there's a process that takes in an observation X and assigns it to one of 3 classes: A, B, or C. It's believed that this process routinely assigns observations to class A when they should'...
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How to ensemble predictions from image classifier and text classifier?

I am doing multiclass classification based on images and text. I have predictions from both image classification and text. I am not sure how to combine them. Should I use probabilities as a feature to ...
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Machine Learning, which kind of classification should i use?

So im trying to make a ML classifier model to my data. My data has many X(variables [texts, integers, binaries etc.]) and 5 output(Y) information. In short, lets say i have 5 different places to put ...

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