Questions tagged [ensemble-modeling]

In machine learning, ensemble methods combine multiple algorithms to make a prediction. Bagging, boosting, and stacking, are some examples.

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17 views

Low leves of probability observed after modelling.Is it right to scale the probability

I have done modelling on imbalanced class , without any sampling methods. Event rate is around 0.1 ,After modelling I am getting probalities more at the lower side close to zero.I have tried differnt ...
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1answer
80 views

Can I use SVC() as a base_estimtor for ensemble methods?

I am currently testing out a few different ensemble methods on my dataset. I've heard that you can also use support vector machines as base learners in boosting and bagging methods but I am not sure ...
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Can bagging ensemble consist of heterogeneous base models?

Bagging or bootstrap aggregation seems to make sense for time series forecasting using an ensemble because bagging randomizes subsets of the data with replacement. However, I've only seen bagging used ...
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30 views

Creating a sub-model from pre-trained model

I have a pre-trained model having the following architecture: ...
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11 views

Domain specific language to describe ensemble model

I'm looking for some tool/library/widely used approach to describe Hierarchical Model structure like ensemble: It's absolutely straightforward how to do it with simple ensemble like It can be ...
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1answer
416 views

Can you combine two xgboost models into one?

If you have built two different xgbost models, with say 100 trees each, is it possible to combine into an xgboost model with 200 trees?
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1answer
467 views

What is the selection criteria to choose between XGBoost and Random Forest

I am trying to understand - when would someone choose Random Forest over XGBoost and vice versa. All the articles out there highlights on the differences between both. I understand them. But when ...
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3answers
2k views

ValueError: "The estimator should be a classifier"

I am adapting sklearn-extension ELMClassifier to be accepted as base_estimator to both VotingClassifier and AdaboostClassifier. ...
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1answer
24 views

What should I use as training data for base (level 1) classifiers in ensembling?

Can I just take all training data that I have, train the base models on them and then take their results and use them for training level 2 model? Is this a good practice, or should it be done ...
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1answer
728 views

Is there any difference between a weak learner and a weak classifier?

While reading about decision tree ensembles Gradient Boosting, AdaBoost etc. I have found the following two concepts weak learner and weak classifier. Are they the same? If there is any difference ...
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1answer
44 views

How many models shall be used in ensemble modelling?

I wish to make an ensemble of deep models to solve a classification problem. I want to know how many models shall be used to create that ensemble to ensure unbiased results. I have head 30+ models ...
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1answer
232 views

What's wrong with RF/SVM with word embedding (GloVe)?

I searched many times in google for examples on word embedding (specifically GloVe) with Random forest and I couldn't find any single example. For GloVe, it was all either LSTM or CNN. Maybe there's ...
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1answer
28 views

is it possible to use the train result as another feature and retrain?

is it possible to use the train result as another feature and retrain? for example I make prediction with classification and add this result to the table and train xgboost?
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2answers
101 views

Hyperparameter optimization, ensembling instead of selecting with CV criteria

While burning CPUs performing a CV selection on a thin grid put on some hyperparameter space. I am using the `scikit-learn' API, for which the end result is a single point on the hyperparameter space, ...
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How to Predict Employee count of businesses using Keras classifiers

I am trying to predict the amount of employees a business has based on a set of input variables. I am using things like the business's age, transaction details, geographic location, business structure ...
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50 views

How to estimate the marginal distribution of a class with respect to one predictor in a classification task?

I have a dataset with a binary dependent variable $y \in \{0,1\}$ and a set of predictors $x1,x2,..,t$. Here, $t$ is the time in minutes (in 24 hrs, that is $t \in (0,1440)$). I want to estimate the ...
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1answer
20 views

When should we start using stacking of models?

I am solving a Kaggle contest and my single model has reached score of 0.121, I'd like to know when to start using ensembling/stacking to improve the score. I used lasso and xgboost and there ...
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2answers
1k views

SHAP value can explain right?

I face a problem with using SHAP value to interpret the Tree-based model. (https://github.com/slundberg/shapsd) First, I have input around 30 features and I have 2 features that have high positive ...
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21 views

Combining several Multi-Output-Models into a single Multi-Output-Model

I'm trying to create a k-Nearest-Neighbor based model of 76-dimensional input data $I$ and 44-dimensional output data $O$. Through domain knowledge I know that only certain input dimensions are ...
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0answers
23 views

Is there a universal convergence rate when stacking models/experts?

It's fairly common to see people stacking different models when chasing marginal gains in contexts such as Kaggle competitions or the Netflix challenge. I would like to know about the mathematics ...
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1answer
38 views

Deep model ensemble giving different results

I am making an ensemble of deep models for solving a classification problem. The initial weights follow the default distribution of keras layers. Each time I run ...
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2answers
895 views

Random forest vs majority voting

I'm using spark with scala to implement majority voting of decision trees and random forest (both are configured in the same way - same depth, the same amount of base classifiers etc.). Dataset is ...
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1answer
202 views

Combining multiple neural networks with different activation functions

I have 3 neural networks where each has as a different activation function: Sigmoid, Tanh and Softmax. I am planning to average their final predictions, but as we know the functions doesn't have the ...
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2answers
88 views

Drawing validation set from test set

I am building a 3 neural network models on dataset that is already separated to train and test sets. From my analysis, I found that this dataset has values on test set which don't exist in the train ...
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2answers
102 views

Ensemble Techniques - Bagging | Subset size

I do have a question on ensemble techniques Baggging/Boosting. - What would be the subset size for Bagging?
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1answer
30 views

Ensemble Techniques - Boosting

I understand boosting is a sequential learning technique and it use the prediction from previous model as a dataset for new model ,after adding weight to the misclassified data points. The point ...
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1answer
1k views

Training an ensemble of small neural networks efficiently in TensorFlow 2

I have a bunch of small neural networks (say, 5 to 50 feed-forward neural networks with only two hidden layers with 10-100 neurons each), which differ only in the weight initialization. I want to ...
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2answers
198 views

Gradient boosting how can accuracy increase when we lower the depth of tree?

What I don't understand about gradient boost is, doesn't lowering height of the tree means we use fewer features in our model? From my model I get the highest accuracy when the depth is one. Meaning ...
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Named Entity Recognition for Sesotho sa Leboa (Sepedi) one of the South African Official Language [closed]

I'm looking for model to used to develop NER for Sepedi?
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1answer
184 views

How to optimize hyperparameters in stacked model?

I was wondering whether somebody could explain how to optimize hyperparameters for the base learners and meta algorithm when stacking? In many tutorials they seem to be plucked out of thin air! ...
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1answer
133 views

How are Decision Trees averaged in Random Forest?

We all know that a Random Forest is an ensemble of Decision Trees, whose results are averaged. Every source I find simply talks about "averaging trees", but how does this "averaging of trees" happens?...
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1answer
201 views

Weighted Linear Combination of Classifiers

I am trying to build an ensemble of classifiers whereby I want my algorithm to learn a set of weights such that it can weight the outputs of different classifiers for a set of data points. I am ...
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14 views

Ensemble learning for multiple hypothesis classes

Just to confirm if the following description falls in the category of ensemble learning. Suppose given a training set $D=\{(X,Y)\}$ we are asked to train a regressor. But now the way we do it is to ...
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2answers
59 views

Understanding why ensembling only improves marginally

I have two models, A and B, trained on Imagenet. Their accuracies on Imagenet validation set are 35.6% and 28.64% respectively, while the accuracy of their ensemble (averaging their scores) is 35.68%. ...
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20 views

Would it make technical sense to model its two known subelements separately (CLV example)?

Let's assume Customer Lifetime Value (CLV) is defined as average basket x frequency. Option A is to build model predicting CLV ...
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1answer
491 views

checking model stability - Performance for different class

I tried to do multi-class classification problem. The goal is to predict whether the match will be won by HomeTeam, AwayTeam or Draw. I did feature engineering from the attributes and finally came up ...
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1answer
3k views

Is there any implementation of Extended Isolation Forest algorithm in R/Python?

I am using isofor package for regular Isolation Forest but I came by an article about Extended Isolation Forest and need your advise which package has this ...
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203 views

Ensemble Method using XGBoost and RotationForest python

How can I create an ensemble model using XGBoost and Rotation Forest in Python?
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1answer
243 views

Voting classifier using grid search for Time Series

I have three models: Arima Auto ARIMA Double Exponential Smoothing I would like to apply an ensemble method - a voting method and allow the classifier to learn weights for these three models. I ...
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1answer
47 views

Building Stacking machine learning model using three base classifiers

I did a stacking using three base classifiers RF, NB, KN N and metamodel random forest or SVM using sklearn library But which is strange each time i change the metamodel i got the same results. Is it ...
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51 views

Is linear regression on the trees of XGBoost (rather than taking their mean) useful/popular?

Given training data $(\underline{x}_1, y_1),...,(\underline{x_N}, y_N)$, one can choose a variety of ensemble method for trees. These algorithms output a set of trees $T_1, ..., T_n$, and then the ...
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1answer
1k views

Difference between bagging and boosting

Can anyone explain me the basic difference between bagging and boosting and which technique can be used in which scenario?
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1answer
27k views

Adaboost vs Gradient Boosting

How is AdaBoost different from a Gradient Boosting algorithm since both of them use a Boosting technique? I could not figure out actual difference between these both algorithms from a theory point of ...
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1answer
324 views

best activation function for ensemble?

i have created some logistic regression model (different preprocessing) with softmax function. and i mix all model with an ensemble with a hierarchical method. so the output of all model (base) will ...
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2answers
119 views

What methods can be used to detect duplicacy in image dataset?

I want to remove duplicate images from a dataset of 50Million images. What is the best method to detect all the duplicates? Do you think one shot learning is good for this?
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1answer
245 views

Why Extra-trees should only be used within ensemble methods?

I was reading scikit-learn documentation for Extremely Randomized Trees and I found this warning: Warning: Extra-trees should only be used within ensemble methods. Why is that?
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1answer
88 views

Combining outputs of ridge regression models?

I am facing an issue where I have 7 sets of different variables/columns/predictors. I am trying to predict same target variable and I want to observe the importance/effect of all the sets according ...
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0answers
541 views

Combining image and scalar inputs into a neural network

I'm looking at the best way of combining CNN with image input and a scalar value. I know that one of the ways is to concatenate flatten layer with this scalar value. But flatten layer consist for ...
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0answers
86 views

heterogeneous input features for estimators in sklearn.ensemble.VotingClassifier

I would like to do ensemble on my model. Two of them are SVM and XGBoosting. SVM could not tolerate null value and XGB can do it. So I have different features for each of them. but when ...
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2answers
3k views

Categorical data for sklearns Isolation Forrest

I'm trying to do anomaly detection with Isolation Forests (IF) in sklearn. Except for the fact that it is a great method of anomaly detection, I also want to use it because about half of my features ...