Mempersiapkan RandomizedSearch

Semester lalu, profesor Anda menantang kelas untuk membangun model prediktif guna memprediksi nilai ujian akhir. Anda mencoba menjalankan beberapa model dengan memilih hyperparameter secara acak. Namun, menjalankan tiap model mengharuskan Anda mengodekannya satu per satu.

Setelah mempelajari RandomizedSearchCV(), Anda meninjau kembali tantangan profesor untuk membangun model terbaik. Pada latihan ini, Anda akan menyiapkan tiga masukan yang diperlukan untuk menyelesaikan pencarian acak.

Latihan ini adalah bagian dari kursus

Validasi Model di Python

Petunjuk latihan

Selesaikan dictionary parameter dengan menambahkan daftar untuk parameter max_depth dengan opsi 2, 4, 6, dan 8.
Buat model regresi random forest dengan sepuluh pohon dan random_state 1111.
Buat penilai mean squared error untuk digunakan.

Latihan interaktif praktis

Cobalah latihan ini dengan menyelesaikan kode contoh berikut.

from sklearn.ensemble import RandomForestRegressor
from sklearn.metrics import make_scorer, mean_squared_error

# Finish the dictionary by adding the max_depth parameter
param_dist = {"____": [____],
              "max_features": [2, 4, 6, 8, 10],
              "min_samples_split": [2, 4, 8, 16]}

# Create a random forest regression model
rfr = ____(____=10, ____=1111)

# Create a scorer to use (use the mean squared error)
scorer = ____(____)

Edit dan Jalankan Kode

Latihan ini adalah bagian dari kursus

Validasi Model di Python

SkillTag.level.intermediateSkillTag.label

4.9+

Mulai Kursus Gratis

Before we can validate models, we need an understanding of how to create and work with them. This chapter provides an introduction to running regression and classification models in scikit-learn. We will use this model building foundation throughout the remaining chapters.

Exercise 1: Introduction to model validation Exercise 2: Modeling steps Exercise 3: Seen vs. unseen data Exercise 4: Regression models Exercise 5: Set parameters and fit a model Exercise 6: Feature importances Exercise 7: Classification models Exercise 8: Classification predictions Exercise 9: Reusing model parameters Exercise 10: Random forest classifier

This chapter focuses on the basics of model validation. From splitting data into training, validation, and testing datasets, to creating an understanding of the bias-variance tradeoff, we build the foundation for the techniques of K-Fold and Leave-One-Out validation practiced in chapter three.

Exercise 1: Creating train, test, and validation datasets Exercise 2: Create one holdout set Exercise 3: Create two holdout sets Exercise 4: Why use holdout sets Exercise 5: Accuracy metrics: regression models Exercise 6: Mean absolute error Exercise 7: Mean squared error Exercise 8: Performance on data subsets Exercise 9: Classification metrics Exercise 10: Confusion matrices Exercise 11: Confusion matrices, again Exercise 12: Precision vs. recall Exercise 13: The bias-variance tradeoff Exercise 14: Error due to under/over-fitting Exercise 15: Am I underfitting?

Holdout sets are a great start to model validation. However, using a single train and test set if often not enough. Cross-validation is considered the gold standard when it comes to validating model performance and is almost always used when tuning model hyper-parameters. This chapter focuses on performing cross-validation to validate model performance.

Exercise 1: The problems with holdout sets Exercise 2: Two samples Exercise 3: Potential problems Exercise 4: Cross-validation Exercise 5: scikit-learn's KFold()Exercise 6: Using KFold indices Exercise 7: sklearn's cross_val_score()Exercise 8: scikit-learn's methods Exercise 9: Implement cross_val_score()Exercise 10: Leave-one-out-cross-validation (LOOCV)Exercise 11: When to use LOOCV Exercise 12: Leave-one-out-cross-validation

The first three chapters focused on model validation techniques. In chapter 4 we apply these techniques, specifically cross-validation, while learning about hyperparameter tuning. After all, model validation makes tuning possible and helps us select the overall best model.

Exercise 1: Pengantar hyperparameter tuning Exercise 2: Membuat Hyperparameter Exercise 3: Menjalankan model menggunakan rentang Exercise 4: RandomizedSearchCV Exercise 5: Mempersiapkan RandomizedSearch

Latihan Saat Ini

Exercise 6: Menerapkan RandomizedSearchCV Exercise 7: Memilih model final Anda Exercise 8: Akurasi klasifikasi terbaik Exercise 9: Memilih model precision terbaik Exercise 10: Kursus selesai!