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Questions tagged [ensemble-modeling]

The tag has no usage guidance.

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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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30 views

Adaboost vs Gradient Boosting

How AdaBoost is different than Gradient Boosting algorithm since both of them works on Boosting technique? I could not figure out actual difference between these both algorithms from theory point of ...
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1answer
16 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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1answer
31 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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How to deal with overfitting in Gradient boosting classification algorithm?

I am training my model on Gradient boosting algorithm with parameters as follows: learning rate: 0.1 number of iterations: 100 depth of tree: 12 I am not getting the output for cross-validation to ...
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1answer
38 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
24 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
24 views

Why should each layer's child network output be close to parent network's output for variance regularizer?

I am reading up on PEA (Pseudo ensemble agreement) regularizer. specificaly in the neural networks domain. It introduces the concept of perturbing the model a little and forcing the model to make ...
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0answers
72 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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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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1answer
71 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 ...
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0answers
6 views

How to optimize stacking?

I'm wondering if there is a way to find the optimal weights when stacking multiple models? For example if I have five models which perform similarly, how do I find if I should discard some altogether, ...
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1answer
39 views

What is the meaning of the term “pipeline” within data science?

Note: this question was asked and removed just before I posted my answer below, so am repeating the general idea here People often refer to pipelines when talking about models, data and even layers ...
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Why does prediction by a consensus of classifier work better than prediction by a single classifiers?

I have seen that consensus of classifiers (taking say 5 separate classifiers) and obtaining the final labeling of the unknown sample based on the voting method (whichever class gets the predicted the ...
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Selecting the best combination of machine learning models for voting

I am thinking about using Sklearn's VotingClassifer for a dataset. I have heard about people winning in machine learning competitions (like those from Kaggle) by correctly utilizing voting/stacking. ...
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1answer
20 views

Ensemble models - neural network input both original data and predictions of other models?

From my understanding in order to improve accuracy with ensemble models you need a wide range of independent ensemble methods. I was wondering whether using the ouput of a random forest model as one ...
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0answers
49 views

Prevent overffitting in model stacking with training on the same target

I'm trying to solve Quora Question Pairs with model stacking. My first layers are: CNN trained to predict the same target as whole model should "Magic features" like question frequency in whole ...
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1answer
45 views

How to construct a self learning process for an ensemble model?

I have two different (regression) models spitting out predictions on a daily basis for the same dependent variable. My intention is to assign weights to those two predictions and calculate a weighted ...
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1answer
132 views

Geometric and harmonic means in ensembling methods

When using ensembling methods for regression, a common approach is to average (using the arithmetic mean) the outputs of the weak learners in order to obtain the output of the ensemble. Is there a ...
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2answers
1k views

How to avoid memory error with Pandas pd.read_csv method call with GridSearchCV usage for DecisionTreeRegressor model?

I have been implementing a DecisionTreeRegressor model in Anaconda environment with a data set sourced from a 20 million row, 12-dimensional CSV file. I could get the chunks off of the data set with ...
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3answers
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What are the individual models within a machine learning ensemble called?

I am aware that an ensemble machine learning model is a stack of two or more machine learning models. Is there a word to refer to those individual models that go into the ensemble model? (i.e. a ...
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2answers
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Questions on ensemble technique in machine learning

I am studying the ensemble machine learning and when I read some articles online, I encountered 2 questions. 1. In this article, it mentions Instead, model 2 may have a better overall performance ...
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49 views

Ensemble Classifier (brew package) - KeyError: '[290 109 240 11 524] not in index'

I am using Ensemble Classifiers from the package brew 0.1.4 and was trying to create dynamic selection classifier from the following example. So my code snippet is like this: ...
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1answer
41 views

Multi-dimensional regression with ensemble models?

I'm curious to know whether boosting, random forests or other types of ensemble models can perform multi-dimensional regression. To be precise: That means multiple outputs (multi-dimensional labels) ...
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AdaBoost - Ensemble model perform poor than best weak classifier

Can Adaboost's ensemble classifier perform worse than the best of the weak learners considered? If so when in what case of weak learner the ensemble learning does not perform better?
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1answer
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How to approach model reporting task

I have been tasked to report on an ensemble model that was created in h2o which includes several model subtypes such as Random Forest, GBM, linear models etc. The end goal is to predict churn rates ...
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1answer
67 views

Retrieve user features in real time from UserId for prediction

Let's say I'm building an app like Uber and I want to predict the user's most likely destination based on the user's past history, current latitude/longitude, and time/date. Here is the proposed ...
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1answer
52 views

testing new data in model

I have ensembled 3 algorithms as below, ...
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2answers
51 views

Combining Different Models

I have N models, each of them are used to predict on a set of data. I am currently combining their predictions by averaging across rows. Need suggestions on combining their predictions. End goal is to ...
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1answer
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Re: Missing Value

I have a large dataset that has session length records per user basis. And I am trying to predict the purchase behaviour based on the session length. But this data has multiple zero in the session ...
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2answers
328 views

Taking average of multiple neural networks?

I'm fitting a neural network using a very small data set, so try splitting the data into training and validation sets. (there is a separate test set) If I split training/validation randomly multiple ...
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2answers
96 views

How to create an ensemble that gives precedence to a specific classifier

Suppose that in a binary classification task, I have separate classifiers A, B, and C. If I ...
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0answers
25 views

How to Compare resampling methods (Dolan-More Curve)

I read about comparing data resampling methods in this publication: https://arxiv.org/abs/1707.03905 In it, they used the Dolan-More Curve. I have been trying to read more about it but can't find ...
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38 views

Can I automate stacking?

I have learned that stacking different methods works well for machine learning problems? Do we have a clear text (any book/article/blog) that can state which methods to stack were in the layers (base ...
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2answers
69 views

Ensemble Model vs Normal model

If I get 95+ % accuracy in normal models, should I still consider Ensemble models? Why should I choose Ensemble models over normal models?
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1answer
90 views

Ensemble Probabilities of the different models

I have a Multiclass Dataset and I am getting probabilities of classes from RandomForest. However, I want to divide the dataset for each class as examples of either the case belongs to that class or ...
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1answer
39 views

How to average classifiers with AUC metric?

I am modeling a binary classification and my loss function is the gini function (normalized area under the curve). Here's my implementation: Split the data with k-folds Train k classifiers Now I ...
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2answers
63 views

Learning Algorithm that decide which model gives better results for each testing instance

Is their any existing Ensemble technique which uses subset of training data to predict which algorithm is better for predicting each instance of testing data? Let's say we have N sized training set ...
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1answer
925 views

Sklearn Aggregating Multiple Fitted Models Into A Single Model? (binary classification)

My problem context: dataset too big to fit into memory. binary classification [0,1] 30 csv files in a directory with exactly 30,000 samples (rows) each file contains 15,000 ...
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28 views

Systematic combination of already accurate classifiers

For a document classification task, I am equipped with at least two already good performing classifiers in terms of accuracy (ca. 80% for a classification task involving 7 classes). Since both ...
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1answer
868 views

How can I do tree_method ='exact' in XGBoost classifier?

I am doing XGBoost classification on a huge data set and its showing: ...
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2answers
207 views

How to measure the correlation of different algorithms

In stacked generalization, several algorithms are trained on the training set (i.e. at layer 1) and their predictions are then stacked using a layer 2 model. In many documentations, it is said that it ...
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1answer
31 views

What kind of algorithms can be used as a stacker in stacked generalization

In stacked generalization, several algorithms (I use some random trees, booster trees, ...) are first trained and used to make the predictions, which are used as input for another algorithm. However, ...
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1answer
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Why some people add results from PCA and other dimensional reductions techniques as features

I often see in a well-known datascience competition platform, that a lot of people apply some dimension reductions techniques, but instead of using it to reduce the number of features (complexity) of ...
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1answer
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How predictions of level 1 models become training set of a new model in stacked generalization.

In stacked generalization, if I understood well, we divide the training set into train/test set. We use train set to train M models, and make predictions on test set. Then we use the predictions as ...
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2answers
65 views

How to use an existing model as in input into a new model

We have a click-model which is currently being used for search ranking in production, and I want to create a new model which takes the old model click probability as one input and adds some other ...
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2answers
180 views

Ensemble learning [closed]

I am currently working to build a mathematical model to predict the stock market. I learned that the best way to do such thing is no longer to make one big best model, but rather to gather several ...
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2answers
765 views

Improving classifier performances in R for imbalanced dataset

I have used an "adabag"(boosting + bagging) model on an imbalanced dataset (6% positive), I have tried to maximized the sensitivity while keeping the accuracy above 70% and the best results I got were:...
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1answer
1k views

Ensemble modelling using model's probabilities

In a classification project, on the training sets, I ran a selection of classifiers. These give me about 20-30% accuracy at best. For each sample, I generate probabilities of each class. I want to ...