Many Errors Calculating Mean / Variance And Standard Deviation

Apr 28, 2014

It may be (it is highly likely) possible that I have royally stuffed this up. I am attempting to write a program that asks a user for a file name, gets the number of entries and if there is more than one entry calculate the mean, variance and standard deviation. This is my code so far:

/* Calculate contains methods that determines the number of data entries in a file, and calculates the mean, variance and standard deviation of this set
*
************************************************************************/
import java.util.Scanner;
import java.io.*;
public class Calculate {
public static void main(String[] args) throws IOException {
// Create a Scanner object for keyboard input.
Scanner keyboard = new Scanner(System.in);

[Code] ....

The errors I am getting are:

Calculate.java:67: error: ';' expected
mean += mean/String filename;
^
Calculate.java:67: error: not a statement
mean += mean/String filename;

[Code] ....

11 errors

Although I am sure there are many more to come.

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Standard Deviation - Round To 10s Place

Dec 2, 2014

for standard deviation my output is not rounded to the 10's place, how can I make it round to the 10's place. Here is my code.

import java.util.*;
public class chapter7 {
public static final int Max_Number_Scores = 100;
public static int fillArray(double[] scores) {
System.out.print("You entered ");
for (int i = 0; i < scores.length; i++) {
System.out.print(scores[i] + " ");

[code]....

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Apr 20, 2015

Basically I'm trying to compute the standard deviation for a set of numbers and I'm using previously know data to compute this. The data I'm working with is here (note all of this is fake as its for an assignment):

Id,First Name,Last Name,Quiz1,Quiz2,Quiz3,Lab1,Lab2,Assignment1,Exam1,Exam2
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15532,Annette,Myers,2,6,0,14,13,4,77,43

Next this is the code that I know is producing the error:

/**
* Pass in original data from files, and pass in computed grades as arraylist. this returns all of the standard deviations to be printed
*/
public static ArrayList calcStandDev(String data1[], ArrayList<Double> grades, ArrayList<Integer> averages)
{
double standDev = 0;
int j = 0;
//gets rid of first element in string array, makes processing MUCH easier
String[] data = Arrays.copyOfRange(data1, 1, data1.length);
 
[Code] ....

Look for the line with all the ***'s, it is producing the "java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.Integer".

The reason I dont undersand why its producing this error is because temp.get(i) should be a integer - averages.get(i) (is type double), I do believe automatic up casting is present here making them both a double then I multiply it by itself producing a double? I dont understand where the casing is occurring. And just incase you want the formula I'm using for standard deviation here it is:

((x1 - ave)^2 + (x2 - ave) ^2 + (xn - ave) ^ 2) / (n-1)

then squareroot above

Why I'm getting this error! I tried changing a few dataTypes but I just cant avoid exceptions being thrown everywhere .

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Jun 15, 2014

I am trying to create a method that calculates the standard deviation of array. What I want to be able to do is something like this

package standardDevaitionAndMean;
public class StandardDeviationTest {
public static void main (String[] args)
{
int [] array = {12,12,12,12,12,12,12};
standardDev = array.StandardDevation();
System.out.print(standardDev);
}
}

With something like this

package standardDevaitionAndMean;
public class StandardDeviation
{double mean1;
double standDev;
public double Mean(double ... array)
{
for(int i=0; i<array.length;i++)

[Code]...

So basically I want to be able to make an array in a class and be able to calculate its standard deviation with my method in my other class. I know the code I wrote is terrible but I just wanted to show what I am trying to do. I am kind of shaky on how arrays operate

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Oct 24, 2014

The purpose of this program is to import via keyboard Numbers.txt and calculate the mean and standard deviation to Results.txt.I am able to get the mean calculate but when I open the Results.txt the standard deviation is 0. I don't know what is wrong with my code, but I believe it has something to do with the scanner being close. Here is the error message i receive after inputting Numbers.txt.

java.lang.IllegalStateException: Scanner closed
at java.util.Scanner.ensureOpen(Unknown Source)
at java.util.Scanner.hasNext(Unknown Source)
at StatsDemo.main(StatsDemo.java:48)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)

Java Code:

import java.text.DecimalFormat; //for number formatting
import java.util.Scanner; //for keyboard input
import java.io.*; //for using files
public class StatsDemo
{
public static void main(String [] args) throws IOException

[Code] .....

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Jun 20, 2014

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Only idea I've come to so far is to read each number as String and check if it has '.' character, to figure out if it's double and than convert it into right type and add it to correct array.

Also thought that maybe this would be achieveable using Pattern but how to do that?

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I am using Java 1.6.0_06

StackTrace:
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[Code] ....

Errors:
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
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event cannot be resolved
event cannot be resolved
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I am trying to do the following java assignment and every thing seems to work fine except when I put a number<4 or >10 it prints both "Invalid grade!"

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Create a program that asks for results of exams and calculates the mean average of the grades. Grades are floating point numbers between 4 and 10. Program asks for grades until a negative number is typed. If user gives a grade other than a number between 4 and 10, the text "Invalid grade!" will be printed on screen and program asks for another grade. Finally the program prints the number of inputted grades and their mean average on screen as shown in the example print. If no grades were inputted, the notice "You did not input any grades." is the only thing printed on screen.

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Program calculates the average of inputted grades.

Finish with a negative integer.

Input a grade (4-10): 5
Input a grade (4-10): 6,5
Input a grade (4-10): 7,5
Input a grade (4-10): 7
Input a grade (4-10): 0
Invalid grade!
Input a grade (4-10): -4
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Java Code:

import java.util.Scanner;
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[Code] .....

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[Code] .....

And here is what is displayed in the command prompt when I compile my code:

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What am I doing wrong?

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