As the number of boosts is increased the regressor can fit more detail. Pipeline will helps us by passing modules one by one through GridSearchCV for which we want to get the best parameters. Perhaps the most commonly configured hyperparameters are the following: n_estimators: The number of trees in the ensemble, often increased until no further improvements are seen. Features of XGBoost . model_selection import GridSearchCV import numpy as np from pydataset import data import pandas as pd Dec 24, 2017 · In our case, using 32 trees is optimal. #. property feature_importances_ # The impurity-based feature importances. Other hyperparameters in decision trees #. considering all of the samples at each node - for a given attribute. , considering only one sample at each node vs. R2 [ 1] algorithm on a 1D sinusoidal dataset with a small amount of Gaussian noise. 1. May 17, 2021 · In this tutorial, you learned the basics of hyperparameter tuning using scikit-learn and Python. because gbdt is the default parameter for lgbm you do not have to change the value of the rest of the parameters for it (still tuning is a must!) stable and reliable. Pruning is performed by the Decision Tree when we indicate a value to this hyperparameter : Feb 8, 2021 · The parameters in Extra Trees Regressor are very similar to Random Forest. Jul 17, 2023 · Plot the decision tree to understand how features are used. I’m going to change each parameter in isolation and plot the effect on the decision boundary. Dear readers, In this blog, we will build a random forest classifier (RFClassifier) model to detect breast cancer using this dataset from Kaggle. Min samples leaf: This is the minimum number of samples, or data points, that are required to RandomizedSearchCV implements a “fit” and a “score” method. We investigated hyperparameter tuning by: Obtaining a baseline accuracy on our dataset with no hyperparameter tuning — this value became our score to beat. 2. We can explore this relationship by evaluating a grid of parameter pairs. 2012; Huang and Boutros 2016) and Boosting Trees (Eggensperger et al May 11, 2019 · In this article I adapt this to visualize the effect of hyperparameter tuning on key XGBoost parameters. Instead, we can tune the hyperparameter max_features, which controls the size of the random subset of features to consider when looking for the best split when growing the trees: smaller values for max_features lead to more random trees with hopefully more uncorrelated prediction errors. algorithm=tpe. All hyperparameters will be set to their defaults, except for the parameter in question. The other diverse python library for hyperparameter tuning for neural network Feb 15, 2023 · Step 3: Build the first tree of XGBoost. Indeed, optimal generalization performance could be reached by growing some of the Hyperparameter tuning is all about finding a set of optimal hyperparameter values which maximizes the models performance, minimizes loss and produces better outputs. Randomly take K data samples from the training set by using the bootstrapping method. tree import DecisionTreeClassifier from sklearn. The default is 50. However if max_features is too small, predictions can be Optuna is an automatic hyperparameter optimization software framework, particularly designed for machine learning. It features an imperative, define-by-run style user API. n_estimators in [10, 100, 1000] For the full list of hyperparameters, see: Sep 18, 2020 · Specifically, it provides the RandomizedSearchCV for random search and GridSearchCV for grid search. When coupled with cross-validation techniques, this results in training more robust ML models. Dec 20, 2017 · max_depth. Jun 10, 2020 · Here is the code for decision tree Grid Search. max_leaf_nodes int, default=None. Oct 31, 2020 · A hyperparameter is a parameter whose value is set before the learning process begins. And lastly, as answer is getting a bit long, there are other alternatives to a random search if an exhaustive grid search is to expensive. k. A decision tree is boosted using the AdaBoost. Unexpected token < in JSON at position 4. Jun 12, 2023 · The values are determined after iterating through different combinations of hyperparameter values with a model and comparing the metrics/evaluation results. Repeat steps 2 and 3 till N decision trees are created. 2 Jul 1, 2024 · Decision trees are powerful models extensively used in machine learning for classification and regression tasks. Aug 12, 2020 · The only difference between both the approaches is in grid search we define the combinations and do training of the model whereas in RandomizedSearchCV the model selects the combinations randomly. Popular Posts. The max_depth hyperparameter controls the overall complexity of the tree. Aug 6, 2020 · Hyperparameter Tuning for Extreme Gradient Boosting. 0001 to 0. Parameters: X{array-like, sparse matrix}, shape (n_queries, n_features), or (n_queries, n_indexed) if metric == ‘precomputed’, default=None. For example, if this is set to 3, then the tree will use three children nodes and cut the tree off before it can grow any more. , Marzak, A. com/krishnaik06/All-Hyperparamter-OptimizationPlease donate if you want to support the channel through GPay UPID,Gpay: krishnaik0 Aug 27, 2020 · Generally, boosting algorithms are configured with weak learners, decision trees with few layers, sometimes as simple as just a root node, also called a decision stump rather than a decision tree. figure(figsize=(20,10)) tree. However, there is no reason why a tree should be symmetrical. The higher max_depth, the more levels the tree has, which makes it more complex and prone to overfit. com/campusx-official Max depth: This is the maximum number of children nodes that can grow out from the decision tree until the tree is cut off. Simply it creates different subsets of data. The number of decision trees will be varied from 100 to 500 and the learning rate varied on a log10 scale from 0. We will now try adjusting the following set of hyperparameters of this model: “Max_depth”: This hyperparameter represents the maximum level of each tree in the random forest model. 01; 📃 Solution for Exercise M3. They solve many of the problems of individual Decision trees, and are always a candidate to be the most accurate one of the models tried when building a certain application. arange(3, 15)} # decision tree model dtree_model=DecisionTreeClassifier() #use gridsearch to test all Sep 16, 2022 · Pruning is a technique used to reduce the complexity of a Decision Tree. random_state. Grow trees with max_leaf_nodes in best-first fashion. Enter Bayesian Optimization: a probabilistic model-based approach that intelligently explores the hyperparameter space to find optimal values, striking a delicate balance between exploration and exploitation. Feb 1, 2023 · The high-level steps for random forest regression are as followings –. Oct 15, 2020 · 4. Code used: https://github. e. Initializing the X and Y parameters and loading our dataset: iris = load_iris() X = iris. The higher, the more important the feature. AdaBoostRegressor Mar 27, 2023 · Decision tree regressor visualization — image by author. Parameters: criterion{“gini”, “entropy”, “log_loss”}, default=”gini”. Decision tree training is computationally expensive, especially when tuning model hyperparameter via k-fold cross-validation. This means that Hyperopt will use the ‘ Tree of Parzen Estimators’ (tpe) which is a Bayesian approach. Due to its simplicity and diversity, it is used very widely. max_depth: The maximum depth of each tree, often values are between 1 and 10. You can also choose to fix some hyper parameters. The purpose of this article to explore how the performance and the computational time of the random forest model are changing with various hyperparameter tuning methods. Smaller learning rates generally require more trees to be added to the model. ExtraTrees Classifier can be used for classification or regression, in scenarios where computational cost is a concern and Jun 9, 2023 · Random Forest Regressor Random Forest Regressor is an ensemble learning algorithm which combines decision trees and the concept of randomness. The deeper the tree, the more splits it has and it captures more information about how Feb 18, 2021 · In this tutorial, only the most common parameters will be included. Calculation of the Similarity Score for the first tree. Deeper trees can capture more complex patterns in the data, but Dec 12, 2023 · Grid search is one popular kind of hyperparameter tuning, although it is also considered inefficient. Read more in the User Guide. Oct 26, 2020 · Disadvantages of decision trees. Parameters: n_estimators int, default=100 Aug 27, 2020 · Tuning Learning Rate and the Number of Trees in XGBoost. tree import DecisionTreeClassifier. sklearn. We’ll do this for: Jan 7, 2019 · Regression decision tree baseline model; Hyperparameter tuning of Adaboost regression model; AdaBoost regression model development; Below is some initial code. content_copy. Hyperparameter Tuning to improve model training phase Mar 26, 2024 · Develop practical proficiency in implementing decision tree models using Python and scikit-learn, with step-by-step guidance and code explanations. If greater than 1 then it prints progress and performance for every tree. hgb. N. min_sample_split – a parameter that tells the decision tree in a random forest the minimum required number of observations in any given node in order to split it. For more information on Decision tree Regression you can refer to this blog by Ashwin Prasad - Link. Both classes require two arguments. keyboard_arrow_up. This article was published as a part of the Data Science Blogathon. Recall that each decision tree used in the ensemble is designed to be a weak learner. fit(X, y) plt. Sep 4, 2023 · Advantage. Nithyashree V 14 Oct, 2021. For our Extreme Gradient Boosting Regressor the process is essentially the same as for the Random Forest. This hyperparameter is not really to tune; hence let us see when and why we need to set a random_state hyperparameter; many new students are confused with random_state values and their accuracy; it may happen because the algorithm of the decision tree is based on the greedy algorithm, that repeated a number of times by using random selection features and this selection Aug 25, 2023 · Random Forest Hyperparameter #2: min_sample_split. Again, hyperparameter tuning is about finding the optimum - therefore trying out different leaf sizes is advised. Some of the key advantages of LightGBM include: Dec 23, 2017 · In this post, we will focus on one implementation of Bayesian optimization, a Python module called hyperopt. RandomForestRegressor. 299 boosts (300 decision trees) is compared with a single decision tree regressor. g decision tree, XGBoost, LightGBM) has a ‘setting’ or ‘config’ that Jul 26, 2021 · This video simplifies the process, guiding you through optimizing hyperparameters for better model performance. Too low, and you will underfit. Oct 31, 2021 · Fine tuning could then involve doing another hyperparameter search "close to" the current (max_depth, min_child_weight) solution and/or reducing the learning rate while increasing the number of trees. Disadvantage. This article is best suited to people who are new to XGBoost. A decision tree classifier. Create a decision tree using the above K data samples. Empirical Softw. The idea is to measure the relevance of each node, and then to remove (to prune) the less critical ones, which add unnecessary complexity. Decision Tree Regression with AdaBoost #. from sklearn. Set and get hyperparameters in scikit-learn; 📝 Exercise M3. Learn to use hyperparameter tuning for decision trees to optimize parameters such as maximum depth and minimum samples split, enhancing model performance and generalization capabilities. randint’ assigns a random integer to ‘n_estimators’ over the given range which is 200 to 1000 in this case. This function dictates the sample distributions of each hyper-parameter. horvath@inf. A meta-estimator that fits a number of decision tree regressors on various sub-samples of the dataset and uses averaging to improve the statistical performance and control over-fitting. Lgbm gbdt. a. plot_params() # Plot the summary of all evaluted models. If not provided, neighbors of each indexed point are returned. Oct 5, 2022 · Defining the Hyperparameter Space . Utilizing an exhaustive grid search. It aims to maximize the margin (the distance between the hyperplane and the nearest data points of each class Optuna is an automatic hyperparameter optimization software framework, particularly designed for machine learning. Hyperparameter tuning by grid-search; Hyperparameter tuning by randomized-search; 🎥 Analysis of hyperparameter search results; Analysis of hyperparameter Oct 28, 2021 · Optimizing hyper-parameters with Optuna follows a similar process regardless of the model you are using. Some of the hyperparameters that we try to optimise are the same and some are different, due to the nature of the model. Eng. over-specialization, time-consuming, memory-consuming. Hyper-parameter tuning process is different among different ML algorithms due to their different types of hyper-parameters, including categorical, discrete Feb 10, 2021 · Extra Trees is a very similar algorithm that uses a collection of Decision Trees to make a final prediction about which class or category a data point belongs in. Oct 14, 2021 · A Hands-On Discussion on Hyperparameter Optimization Techniques. This means that if any terminal node has more than two Dec 23, 2022 · Here, we are using Decision Tree Regressor as a Machine Learning model to use GridSearchCV. I get some errors on both of my approaches. It is belongs to the supervised learning algorithm family. The function to measure the quality of a split. This parameter is adequate under the assumption that a tree is built symmetrically. Both are very effective ways of tuning the parameters that increase the model generalizability. These parameters include a number of iterations, learning rate, L2 leaf regularization, and tree depth. Here is the parameters I am using for extra trees regressor (I am using GridSearchCV): Oct 10, 2021 · Before jumping to find out the best hyperparameters, let’s have quick look at our baseline decision tree’s overall performance. One of the most important features of Random Forest is that with the help of this algorithm, you can handle Grid search is a technique for tuning hyperparameter that may facilitate build a model and evaluate a model for every combination of algorithms parameters per grid. The maximum depth can be specified in the XGBClassifier and XGBRegressor wrapper classes for XGBoost in the max_depth parameter. ensemble import AdaBoostRegressor from sklearn import tree from sklearn. So the first thing to do is to calculate the similarity score for all the residuals. If you want to discover more hyperparameter tuning possibilities, check out the CatBoost documentation here. The default value of the minimum_sample_split is assigned to 2. Some of the popular hyperparameter tuning techniques are discussed below. Lgbm dart. That is, it has skill over random prediction, but is not highly skillful. : Systematic review study of decision trees based software development effort estimation. 01; Automated tuning. In the previous notebook, we showed how to use a grid-search approach to search for the best hyperparameters maximizing the generalization performance of a predictive model. This is the score that the tree splits intend to augment. We can also plot the same with another hyperparameter min_samples_leaf, which is the minimum number of observations that should be in the final regions (that we call leaves because at the end of a tree’s ramification, we find leaves!) github link: https://github. We fit a Jan 31, 2024 · Many ML studies investigate the effect of hyperparameter tuning on the predictive performance of classification algorithms. Basically, instead of running a static single Decision Tree or Random Forest, new trees are being added iteratively until no further improvement can be Enable verbose output. Random Forest are an awesome kind of Machine Learning models. Parameters like in decision criterion, max_depth, min_sample_split, etc. The official page of XGBoost gives a very clear explanation of the concepts. Dtree= DecisionTreeRegressor() parameter_space = {'max_features If the issue persists, it's likely a problem on our side. Aug 1, 2019 · Gradient Boosting Decision Tree (GBDT) Gradient Boosting is an additive training technique on Decision Trees. The structure of decision trees resembles the flowchart of decisions helps us to interpret and explain easily. br Tomáš Horváth Eötvös Loránd University Faculty of Informatics Budapest, Hungary tomas. plot_cv() # Plot the best performing tree. treeplot() 3 days ago · It uses parallel computation in which multiple decision trees are trained in parallel to find the final prediction. The next is max_depth. Gradient Tree Boosting . Explore and run machine learning code with Kaggle Notebooks | Using data from Heart Disease Prediction. it is the default type of boosting. plot_tree(clf, filled=True, fontsize=14) We end up having a tree with 5 leaf nodes. The first step is to set up a study function. It provides a flexible and efficient platform Aug 31, 2023 · Traditional methods of hyperparameter tuning, such as grid search or random search, often fall short in efficiency. The hyperparameter min_samples_split is used to set the minimum number of samples required to split an internal node. A small change in the data can cause a large change in the structure of the decision tree. DecisionTreeClassifier(max_leaf_nodes=5) clf. data[:, 2 :] y =iris. In line 3, the hyperparameter values are defined as a dictionary where keys are the hyperparameter name and a list of values containing hyperparameter values we want to try. Apr 27, 2021 · An important hyperparameter for AdaBoost algorithm is the number of decision trees used in the ensemble. The decision leaf of a tree is the node where the 'actual decision' happens. It also implements “score_samples”, “predict”, “predict_proba”, “decision_function”, “transform” and “inverse_transform” if they are implemented in the estimator used. , Zakrani, A. As such, one-level decision trees are used, called decision stumps. Internal parameter defaults. Nov 5, 2021 · Here, ‘hp. Oct 22, 2021 · The default and most common learner is a decision tree stump (a decision tree with max_depth=1) as we discussed earlier. SVM works by finding a hyperplane in a high-dimensional space that best separates data into different classes. An empirical study on hyperparameter tuning of decision trees Rafael Gomes Mantovani University of São Paulo São Carlos - SP, Brazil rgmantovani@usp. Jul 28, 2020 · clf = tree. Also, we’ll practice this algorithm using a training data set in Python. Refresh. For BOOSTED_TREE_CLASSIFIER models, the default is ROC_AUC. However, the performance of decision trees highly relies on the hyperparameters, selecting the optimal hyperparameter can sign Dec 21, 2021 · Thank you for reading! These are 5 hyperparameters that I normally tweak when I develop decision trees. Decide the number of decision trees N to be created. Extra Trees differs from Random Forest, however, in the fact that it uses the whole original sample as opposed to subsampling the data with replacement as Random Forest does. We might use 10 fold cross-validation to search the best value for that tuning hyperparameter. Learning decision trees was essential in my studies on DS and ML — it was the algorithm that helped me to grasp the huge impact that hyperparameters can have in your algo’s performance and how they can be key for the failure or success of a project. If 1 then it prints progress and performance once in a while (the more trees the lower the frequency). A deeper tree performs well and captures a lot of information about the training data, but will not generalize well to test data. Another important hyperparameter of decision trees is max_features which is the number of features to consider when looking for the best split. The deeper the tree, the more splits it has and it captures more information about the data. extra-trees) on various sub-samples of the dataset and uses averaging to improve the predictive accuracy and control over-fitting. model_selection and define the model we want to perform hyperparameter tuning on. model_selection import GridSearchCV def dtree_grid_search(X,y,nfolds): #create a dictionary of all values we want to test param_grid = { 'criterion':['gini','entropy'],'max_depth': np. This tutorial was designed and created by Rukshan Pramoditha, the Author of Data Science 365 Blog. A leaf node is the end node of a decision tree and a smaller min_sample_leaf value will make the model more vulnerable to detecting noise. There are a fixed number of trees added and with each iteration which should show a reduction in loss function value. 2012) and ANNs (Bergstra and Bengio 2012); or ensemble algorithms, such as Random Forest (RF) (Reif et al. plot() # Plot results on the validation set. The first parameter to tune is max_depth. Thanks to our define-by-run API, the code written with Optuna enjoys high modularity, and the user of Optuna can dynamically construct the search spaces for the hyperparameters. It does not scale well when the number of parameters to tune increases. Initializing a decision tree classifier with max_depth=2 and fitting our feature This chapter demonstrates hyperparameter tuning for river’s Hoeffding Adaptive Tree Regressor with the Friedman drift data set . Since the number of evaluations increases Explore and run machine learning code with Kaggle Notebooks | Using data from No attached data sources In this video, we will use a popular technique called GridSeacrhCV to do Hyper-parameter tuning in Decision Tree About CampusX:CampusX is an online mentorshi Nov 20, 2020 · Tuning hyper-parameters is considered a key component of building an effective ML model, especially for tree-based ML models and deep neural networks, which have many hyper-parameters [6]. Both techniques evaluate models for a given hyperparameter vector using cross-validation, hence the “ CV ” suffix of each class name. Nov 28, 2023 · from sklearn. Hyperparameter tuning. Sep 10, 2020 · In this case, I'd suggest you shuffle your data, do a test train split again, and check the CV score while training with the new hyper parameters. Values must be in the range [0, inf). It is engineered for speed and efficiency, providing faster training times and better performance than older boosting algorithms like XGBoost. The query point or points. It elucidates two primary hyperparameters: `max_depth` and `min_samples_split`, explaining their significance and how improper tuning can lead to underfitting or overfitting. 3. I will be using the Titanic dataset from Kaggle for comparison. Aug 6, 2022 · Photo by Riccardo Annandale on Unsplash. We’ll learn the art of XGBoost parameters tuning and XGBoost hyperparameter tuning. Applying a randomized search. Returns indices of and distances to the neighbors of each point. elte. n_estimators: The maximum number of estimators (models) to train sequentially. 24, 1–52 (2019) Article Google Scholar Najm, A. So we have created an object dec_tree. The parameters of the estimator used to apply these methods are optimized by cross Nov 21, 2019 · Hyperparameter tuning is an important step in building a learning algorithm model and it needs to be well scrutinized. The lesson also demonstrates the usage of Sep 3, 2021 · As the name suggests, it controls the number of decision leaves in a single tree. Some of the most common hyperparameters include: Choice of splitting loss function, used to determine ( f, s) at a given node. Jan 16, 2023 · Tree-specific hyperparameters control the construction and complexity of the decision trees: max_depth : maximum depth of a tree. Using Bayesian optimization for parameter tuning allows us to obtain the best Jun 12, 2024 · A Support Vector Machine (SVM) is a supervised machine learning algorithm used for classification and regression tasks. Mar 29, 2021 · Minku, L. This class implements a meta estimator that fits a number of randomized decision trees (a. If you don’t know what Decision Trees or Random Forest are do not have an ounce of worry; I got you Feb 5, 2024 · Optuna is an open-source hyperparameter optimization framework designed for automating the process of tuning machine learning model hyperparameters. Ideally, this should be increased until no further improvement is seen in the model. L. This indicates how deep the built tree can be. @user12897935 Don't use GridSearch for its a brute force method. However, a grid-search approach has limitations. Aug 28, 2020 · Bagged Decision Trees (Bagging) The most important parameter for bagged decision trees is the number of trees (n_estimators). This can vary between two extremes, i. max_depth. For BOOSTED_TREE_REGRESSOR models, the default is R2_SCORE. We’ll measure the effect of this hyperparameter soon. Here, X is the feature attribute and y is the target attribute (ones we want to predict). Sep 30, 2023 · Introduction to LightGBM and Hyperparameter Tuning. The most common options available are categorical, integer, float, or log uniform. 01; Quiz M3. Best nodes are Jul 9, 2024 · If you aren't running hyperparameter tuning, or if you are and you don't specify an objective, the default objective is used. A decision tree regressor. Dec 21, 2021 · In lines 1 and 2, we import GridSearchCV from sklearn. Module overview; Manual tuning. hu Ricardo Cerri Federal University of São Carlos São Carlos, SP, Brazil cerri@dc Well, there are three options that you can try, one being obvious that you increase the max_iter from 5000 to a higher number since your model is not converging within 5000 epochs, secondly, try using batch_size, since you've got 1384 training examples, you can use a batch size of 16,32 or 64, this can help in converging your model within 5000 iterations, and lastly, you can always increasing Jun 5, 2023 · Also we will learn some hyperparameter tuning techniques. Specify the algorithm: # set the hyperparam tuning algorithm. ExtraTrees Classifier is an ensemble tree-based machine learning approach that uses relies on randomization to reduce variance and computational cost (compared to Random Forest). LightGBM utilizes gradient-boosting decision trees for both classification and regression tasks. 1. Dec 5, 2018 · View a PDF of the paper titled Better Trees: An empirical study on hyperparameter tuning of classification decision tree induction algorithms, by Rafael Gomes Mantovani and 6 other authors View PDF Abstract: Machine learning algorithms often contain many hyperparameters (HPs) whose values affect the predictive performance of the induced models Oct 6, 2023 · 6. Decision Tree Regression Decision Tree Regression builds a tree like structure by splitting the data based on the values of various features. We can see that our model suffered severe overfitting that it I am trying to use to sklearn grid search to find the optimal parameters for the decision tree. For a detailed example of utilizing AdaBoostRegressor to fit a sequence of decision trees as weak learners, please refer to Decision Tree Regression with AdaBoost. plot_validation() # Plot results on the k-fold cross-validation. The first is the model that you are optimizing. This indicates how deep the tree can be. Fine-tuning hyperparameters in a regression tree involves adjusting parameters like 'max_depth,' 'min_samples_split,' and 'min_samples_leaf' to optimize the . While working on data this algorithm create multiple decision trees and combines the predictions of all trees to give final output. 16 min read. Supported criteria are “gini” for the Gini impurity and “log_loss” and “entropy” both for the Shannon information gain, see Mathematical Sep 22, 2022 · Random Forest is a Machine Learning algorithm which uses decision trees as its base. BigQuery ML uses the following default values when building models: An extra-trees regressor. The Hoeffding Adaptive Tree Regressor is a decision tree that uses the Hoeffding bound to limit the number of splits evaluated at each node. Mar 7, 2021 · You can specify hyperparameter values to the class constructor to configure the model. # Plot the hyperparameter tuning. dtreeReg = tree. SyntaxError: Unexpected token < in JSON at position 4. I know some of them are conflicting with each other, but I cannot find a way out of this issue. Good values might be a log scale from 10 to 1,000. It gives good results on many classification tasks, even without much hyperparameter tuning. The first tree is going to be trained with all the residuals as the target. : A novel online supervised hyperparameter tuning procedure applied to cross-company software effort estimation. Most of them deal with the tuning of “black-box” algorithms, such as SVMs (Gomes et al. Each algorithm (e. DecisionTreeRegressor() Step 5 - Using Pipeline for GridSearchCV. target. Its ineffecient for high-dimensional data. DecisionTreeRegressor. Explore and run machine learning code with Kaggle Notebooks | Using data from multiple data sources The lesson centers on understanding and applying hyperparameter tuning to decision trees, a crucial machine learning algorithm for classification and regression tasks. Hyperparameter tuning by randomized-search. tree. suggest. Grid Search Cross In Decision Trees, the parameters consist of the selected features f, and their associated split points s, that define how data propagate through the nodes in a tree. iq yt ay ma wt vo iq hi sc af