Respuesta :
For this project you will need to load data from a file, generate some common statistics from it, and generate a graph known as a histogram from this data, check the code given below to get it.
What is histogram?
A histogram is a visual representation of data points arranged into ranges that the user has chosen. The histogram resembles a bar graph in appearance.
// Analysis.java //
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
public class Analysis {
// method to display the histogram for the input list of sorted ratings (ascending order)
public static void displayHistogram(ArrayList<Double> ratings)
{
int nBooks ;
double r;
System.out.println("Histogram of Amazon Bestseller Ratings");
System.out.println("---------------------------------------");
// loop from ratings minimum-0.1 to maximum+0.1 in steps of 0.1
for(r = ratings.get(0)-0.1;r <= ratings.get(ratings.size()-1)+0.1;r=r+0.1)
{
nBooks = 0;
System.out.printf("%.1f ",r); // display the current rating
// loop to count the number of books that have the same rating as r
for(int i=0;i<ratings.size();i++)
{
// compare r with ith rating
if(Math.abs(ratings.get(i) - r) <= 0.0001) // equal, then increment nBooks by 1
nBooks++;
else if(ratings.get(i) > r) // ith rating > r, then exit the loop since ratings list are sorted in ascending order
break;
}
// display * corresponding to number of books having rating r
for(int i=0;i<nBooks;i++)
System.out.print("*");
System.out.println();
}
System.out.println("---------------------------------------");
}
// method to compute and return the median rating from the input list of sorted ratings(ascending order)
public static double median(ArrayList<Double> ratings)
{
if(ratings.size() > 0) // validate size of list > 0
{
if(ratings.size()%2 == 0) // even number of ratings
{
// median is the average of middle 2 ratings
return (ratings.get((int)ratings.size()/2) + ratings.get((int)(ratings.size()/2)-1))/2;
}
else // odd number of ratings
return (ratings.get((int)(ratings.size()-1)/2)); // median is the middle value
}
return 0;
}
// method to compute and return the mean of input list of sorted ratings (ascending order)
public static double average(ArrayList<Double> ratings)
{
double totalRatings = 0; // initialize totalRatings to 0
// loop over the list of ratings, adding each rating to totalRatings
for(int i=0;i<ratings.size();i++)
totalRatings += ratings.get(i);
if(ratings.size() > 0) // list is not empty
return totalRatings/ratings.size(); // compute average by dividing totalRating by number of ratings
return 0; // list is empty
}
// method to compute and return the standard deviation of input list of sorted ratings (ascending order)
public static double standardDeviation(ArrayList<Double> ratings)
{
double avg = average(ratings); // get the average of all ratings
double stdDev = 0; // initailize the total of squared difference to 0
// loop to calculate sum of square difference of each rating from mean
for(int i=0;i<ratings.size();i++)
{
stdDev += Math.pow(ratings.get(i)-avg,2);
}
if(ratings.size() > 0) // list is not empty
return Math.sqrt(stdDev/ratings.size());
return 0; // list is empty
}
public static void main(String[] args) {
String filename;
Scanner scnr = new Scanner(System.in);
// input the filename
System.out.print("Enter a filename: ");
filename = scnr.nextLine();
scnr.close();
// create a File object
File file = new File(filename);
try {
// open the file in read mode
scnr = new Scanner(file);
// create an empty array list to store rating of each record in file
ArrayList<Double> ratings = new ArrayList<Double>();
String line = scnr.nextLine(); // read and discard the first header line
// loop over the file line by line
while(scnr.hasNextLine())
{
line = scnr.nextLine(); // read a line from file
String[] fields = line.split(","); // split the line into array of String using comma as the delimiter
// since rating is the 3rd field i.e index 2 in input file, convert it to double and insert it in the list
ratings.add(Double.parseDouble(fields[2]));
}
scnr.close(); // close the input file
Collections.sort(ratings); // sort the list in ascending order using the built-in sort method
displayHistogram(ratings); // display the histogram
// display number of records
System.out.println("Total books rated: "+ratings.size());
// display median, average and standard deviation of scores
System.out.printf("Median Score: %.1f\n",median(ratings));
System.out.printf("Average Score: %.1f\n",average(ratings));
System.out.printf("Standard Deviation: %.2f\n",standardDeviation(ratings));
} catch (FileNotFoundException e) {
// file not found, display error and exit the program
System.out.println("ERROR - File "+filename+" not found");
}
}
}
//end of Analysis.java
Learn more about histogram
https://brainly.com/question/16738893
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