A New Dataset

Objectives

We would like to :

Explore a new data set.

Notes

I obtained a dataset of Fruit and Vegetable Process from the USDA.
- I have trimmed it down to FruitPrices.csv.
The first column is the type of Fruit, a string.
The second column is a Form, a string
- Like Fresh, Canned, ....
- We will explore this.
The next column is a price, a float.
The last column is a unit, per pound, per pint, ...
This file had a , in some of the fruit descriptions, so I changed it to be :
- Apples, frozen concentrate became Apples: frozen concentrate
- We are not quite ready to deal with that yet.

We are going to learn something that is outside of the syllabus, basic arrays

An array is a collection of similar data.
We access arrays by an index.
Arrays have a .length method that tells us the length of the array.
Index values are between 0 and length-1

We want arrays, because the string.split method will return an array of strings.

String[] split(String regex)
String[] split(String regex, int limit)
reference.
We will not discuss regular expressions (regex) for now, just a single character will do.
The difference between the two is the second will only split limit times.

We will use these will well formatted data

But there are tricks for when the data might have no value (like ,,)
Go back and read when you encounter this.
You probably want the second form, and give it a large limit.

Here is a starting program

import java.io.*;
import java.util.Scanner;

public class FruitsDemo{
    public static Scanner fileScanner;

    public static void main(String[] args) {
        MakeScanner();

        while (fileScanner.hasNextLine()) {
             data = fileScanner.nextLine();
             System.out.printf("The line is '%s'\n",data);
        }

        fileScanner.close();
    }

    private static void MakeScanner(){
       String fileName = "FruitPrices.csv";
       try {
           fileScanner = new Scanner(new File(fileName));
       } catch (FileNotFoundException  e) {
           System.out.printf("Error could not open %s\n");
       }
    }
}

I built the scanner in MakeScanner because I want to do something else with that.

Parsing the input line becomes much easier.

String[] dataParts;
int i;
        
while (fileScanner.hasNextLine()) {
      data = fileScanner.nextLine();
      System.out.printf("The line is '%s'\n",data);
      dataParts = data.split(",");
      
      int i = 0;
      while (i < dataParts.length) {
          System.out.printf("Part %d is '%s'\n",i, dataParts[i]);
          ++i;
      }
}