Question

java

Challenge Avocado Prices Programming challenge description: Consider a dataset containing the distribution of avocado prices across various reg that dataset, calculate the following summary statistics: 1. min - the minimum of the values 2. max. the maximum of the values 3. mean - the mean of the values 4. std - a corrected sample standard deviation, that uses denominator n - 1 Input: A dataset in CSV format with the avocado prices to summarize. The dataset has the 1. date the date of the observation 2. price - the price of a single avocado 3. region - the name of the region For example: date,price,region 2015-07-19,1.98, Louisville 2015-08-16,1.05, RichmondNorfolk 2015-84-85,1.1, Orlando 2015-07-26,1.12, Grand Rapids 2015-05-31,1.1, Atlanta Output: Print the summary statistics as four real numbers. Print each value on a separate line in 1 min 2. max 3. mean 4 std

Answer 1

Here is the solution if you have any doubts then you can write in the comment section.

Please give feedback.

Solution:

import java.io.File;  
import java.io.FileNotFoundException;  
import java.util.*; 

public class Main 
{
        public static void main(String[] args) 
        {
                //try catch block to handle exceptions 
                try 
                {
                        //open a new file named input.csv
                        File myObj = new File("input.csv");
                        //create Scanner Object
                        Scanner myReader = new Scanner(myObj);
                        //read 1st line, we want to skip this because it contain field name 
                        myReader.nextLine();
                        //varibles
                        double value,sum=0,count=0,min=999999999,max=0;
                        //ArrayList to store values for finding std
                        ArrayList <Double> al=new ArrayList <Double>();
                        //read from file until line is present
                        while (myReader.hasNextLine()) 
                        {
                                // read line and store in data
                                String data = myReader.nextLine();
                                //split string by ,
                                String arr[]=data.split(",");
                                //value is 2nd element of array according to input given in question
                                value=Double.parseDouble(arr[1]);
                                //add value to ArrayList
                                al.add(value);
                                //add value to sum
                                sum+=value;
                                //increment count
                                count++;
                                //calculate max
                                if(value>max)
                                {
                                        max=value;
                                }
                                //calculate min
                                else if(value<min)
                                {
                                        min=value;
                                }
                        }
                        //calculate mean
                        double mean=sum/count;
                        double std=0.0;
                        //loop through all values
                        for(double values:al)
                        {
                                //calculate std
                                std+=Math.pow((values-mean),2);  
                        }
                        //calculate sample std, please be sure that n>1
                        std/=(count-1);
                        //print values
                        System.out.println("Min: "+min);
                        System.out.println("Max: "+max);
                        System.out.println("Mean: "+mean);
                        System.out.println("Std: "+std);
                        //close file
                        myReader.close();
                } 
                catch (FileNotFoundException e) 
                {
                        System.out.println("An error occurred.");
                        e.printStackTrace();
                }
                catch (ArithmeticException Ae)
                {
                        System.out.println("Count should be greater than 1 for std");
                }
        }
}

Input/Output:

input.csv

date,price,region
2015-07-19,1.08,Louisville
2015-08-16,1.05,RichmondNorfolk
2015-04-05,1.1,Orlando
2015-07-26,1.12,GrandRapids
2015-05-31,1.1,Atlanta

A B c D E F 1 2 3 date price 2015-07-19 2015-08-16 2015-04-05 2015-07-26 2015-05-31 region 1.08 Louisville 1.05 RichmondNorfolk 1.1 Orlando 1.12 Grand Rapids 1.1 Atlanta 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

output:

input Min: 1.05 Max: 1.12 Mean: 1.0899999999999999 Std: 7.000000000000012E-4 ... Program finished with exit code 0 Press ENTER to exit console. I

Thank You!