Grubbs testiyle birden fazla aykırı değeri avlama

Grubbs testi, maksimum değerin bir aykırı değer olabileceğini buldu; peki ya daha fazlası varsa? Önceden belirlenen aykırı değerleri veriden çıkarıp Grubbs testini tekrar ederek başka aykırı değerler de bulunabilir.

Test edilen noktayı belirlemek için, en büyük ya da en küçük değeri içeren indeksi bulmak üzere which.min() veya which.max() fonksiyonlarını kullanabilirsin — hangisi olduğunu Grubbs testinin çıktısından biliyoruz, unutma.

Bu egzersiz

R ile Anomali Tespitine Giriş

kursunun bir parçasıdır

Kursu Görüntüle

Uygulamalı interaktif egzersiz

Bu örnek kodu tamamlayarak bu egzersizi bitirin.

# Apply Grubbs' test to the nitrate data
grubbs.test(river$nitrate)

# Find row index of the max of the nitrate data
___(___)

Kodu Düzenle ve Çalıştır

Bu egzersiz

R ile Anomali Tespitine Giriş

kursunun bir parçasıdır

IntermediárioNível de habilidade

4.8+

23 reviews

Kursa Ücretsiz Başlayın

In this chapter, you'll learn how numerical and graphical summaries can be used to informally assess whether data contain unusual points. You'll use a statistical procedure called Grubbs' test to check whether a point is an outlier, and learn about the Seasonal-Hybrid ESD algorithm, which can help identify outliers when the data are a time series.

Exercise 1: Anomalilerden bahsederken neyi kastediyoruz?Exercise 2: Anomali türlerini tanıma Exercise 3: Nehir nitrat verilerini keşfetme Exercise 4: Aşırılıkları Grubbs testiyle sınamak Exercise 5: Normalliğin görsel kontrolü Exercise 6: Grubbs testi Exercise 7: Grubbs testiyle birden fazla aykırı değeri avlama

Geçerli Egzersiz

Exercise 8: Zaman serilerinde anormallikler Exercise 9: Mevsimselliğin görsel değerlendirmesi Exercise 10: Mevsimsel Hibrit ESD algoritması Exercise 11: Seasonal-Hybrid ESD çıktısını yorumlama Exercise 12: Seasonal-Hybrid ESD ve Grubbs testi

In this chapter, you'll learn how to calculate the k-nearest neighbors distance and the local outlier factor, which are used to construct continuous anomaly scores for each data point when the data have multiple features. You'll learn the difference between local and global anomalies and how the two algorithms can help in each case.

Exercise 1: k-nearest neighbors distance score Exercise 2: Exploring wine Exercise 3: kNN distance matrix Exercise 4: kNN distance score Exercise 5: Visualizing kNN distance Exercise 6: Standardizing features Exercise 7: Appending the kNN score Exercise 8: Visualizing kNN distance score Exercise 9: Local outlier factor Exercise 10: LOF calculation Exercise 11: LOF visualization Exercise 12: LOF vs kNN

k-nearest neighbors distance and local outlier factor use the distance or relative density of the nearest neighbors to score each point. In this chapter, you'll explore an alternative tree-based approach called an isolation forest, which is a fast and robust method of detecting anomalies that measures how easily points can be separated by randomly splitting the data into smaller and smaller regions.

Exercise 1: Isolation trees Exercise 2: Fit and predict with an isolation tree Exercise 3: Score interpretation Exercise 4: Isolation forest Exercise 5: Fit an isolation forest Exercise 6: Checking convergence Exercise 7: Visualizing the isolation score Exercise 8: A grid of points Exercise 9: Prediction over a grid Exercise 10: Anomaly contours

You've now been introduced to a few different algorithms for anomaly scoring. In this final chapter, you'll learn to compare the detection performance of the algorithms in instances where labeled anomalies are available. You'll learn to calculate and interpret the precision and recall statistics for an anomaly score, and how to adapt the algorithms so they can accommodate data with categorical features.

Exercise 1: Labeled anomalies Exercise 2: Thyroid data Exercise 3: Visualizing thyroid disease Exercise 4: Anomaly score Exercise 5: Measuring performance Exercise 6: Binarized scores Exercise 7: Cross-tabulate binary scores Exercise 8: Thyroid precision and recall Exercise 9: Working with categorical features Exercise 10: Converting character to factor Exercise 11: Isolation forest with factors Exercise 12: LOF with factors Exercise 13: Wrap-up