Statistik data

Pembersihan Data di Java

Dennis Lee

Software Engineer

Kenali instruktur Anda!

 

Dennis Lee

 

  • Software Engineer di Amazon
  • Teknologi dan operasi
  • Ph.D. Teknik Elektro dan Komputer

 

Foto instruktur

Pembersihan Data di Java

Mengapa kebersihan data penting

 

Title Publish Date Rating Review Count Price
[null] 1/10/23 4.8 165 $30.61
9/13/19 4.8 2,521 $38.00
Clean Code 8/1/08 4.7 5,639 $400.00

 

  • Data kotor: penjualan hilang, kebingungan pelanggan, proyeksi tak andal
  • Solusi: bersihkan data
Pembersihan Data di Java

Garis besar kursus

  1. Nilai kualitas data

 

1_Ch1_L1_.jpg

Pembersihan Data di Java

Garis besar kursus

  1. Nilai kualitas data
  2. Transformasi data

 

2_Ch1_L1_.jpg

Pembersihan Data di Java

Garis besar kursus

  1. Nilai kualitas data
  2. Transformasi data
  3. Validasi data

 

3_Ch1_L1_.jpg

Pembersihan Data di Java

Garis besar kursus

  1. Nilai kualitas data
  2. Transformasi data
  3. Validasi data
  4. Bersihkan data tabel

 

4_Ch1_L1_.jpg

Pembersihan Data di Java

Struktur data kita

import java.time.LocalDate;

public class BookSalesExample {
    private record BookSales(String title, LocalDate publishDate, 
                             int reviewCount,  double rating, double price) {}}

book.rating() // book adalah instance BookSales
Title Publish Date Rating Review Count Price
Python Crash Course 1/10/23 4.8 165 $30.61
The Pragmatic Programmer 9/13/19 4.8 2,521 $38.00
Clean Code 8/1/08 4.7 5,639 $40.00
Pembersihan Data di Java

Mengisi dataset

import java.time.LocalDate;
import java.util.Arrays;
import java.util.List;

// Buat buku dengan title, publishDate, reviewCount, rating, dan price
List<BookSales> books = Arrays.asList(
        new BookSales("Python Crash Course", LocalDate.of(2023, 1, 10),
                      165, 4.8, 30.61),
        new BookSales("The Pragmatic Programmer", LocalDate.of(2019, 9, 13),
                      2521, 4.5, 38.00),
        new BookSales("Clean Code", LocalDate.of(2008, 8, 1),
                      5639, 4.7, 40.00));
Pembersihan Data di Java

Menghitung mean, min, max

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;


public class BookSalesExample {
    public static void main(String[] args) {
        // Buat kalkulator statistik
        DescriptiveStatistics stats = new DescriptiveStatistics();
        // Tambahkan harga tiap buku ke stats
        books.forEach(book -> stats.addValue(book.getPrice()));
    }
}
Pembersihan Data di Java

Contoh output: rentang harga

System.out.printf("Books analyzed: %d%n", books.size());

Books analyzed: 3

System.out.printf("Average price: $%.2f%n", stats.getMean());

Average price: $36.20

System.out.printf("Price range: $%.2f - $%.2f%n", stats.getMin(), stats.getMax());

Price range: $30.61 - $40.00
Pembersihan Data di Java

Menghitung persentil

public class BookSalesExample {
    public static void main(String[] args) {
        // Persentil ke-50 = median
        System.out.printf("Median price: $%.2f%n", stats.getPercentile(50));

        System.out.printf("Normal range: $%.2f - $%.2f%n",
                stats.getPercentile(25), stats.getPercentile(75));
    }
}

Median price: $38.00

Normal range: $30.61 - $40.00
Pembersihan Data di Java

Statistik sebagai kontrol kualitas

  • Metode DescriptiveStatistics
    • .getMean(): harga rata-rata
    • .getMin(), .getMax(): rentang harga
    • .getPercentile(): harga tipikal
  • Temukan isu dengan melihat rentang harga
  • Manfaat
    • Deteksi masalah cepat
    • Skala ke dataset besar
    • Gantikan inspeksi manual

Tumpukan buku

Pembersihan Data di Java

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Pembersihan Data di Java

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