Calculate the mean value of each array, and then determine which average is higher

Question

Calculate the mean value of each array, and then determine which average is higher

After running the code snippet provided, I noticed that it outputs "first" instead of "second". Can you help me verify my logic here? I first calculate both averages and then compare them to return the greater one. Do you see any issues with this approach?

var first = ([100, 80], [100, 100]);
function compare(a, b) {
  sum = 0;
  for(var i = 0; i < a.length; i++) {
    sum += first[i];
    avg1 = (sum/a.length);
  }

  sum2 = 0;
  for(i = 0; i < b.length; i++) {
    sum2 += first[i];
    avg2 = (sum2/b.length);
  }
  if (avg1 > avg2); {
    return ("first");
  }
  if (false) {
    return ("second");
  }
}

javascript

Answer 1

Answer №1

To calculate the average of the elements in arrays a and b, make sure you are summing those elements individually, not from array first.

Moreover, there was a redundant ; after if (avg1 > avg2), which resulted in an empty body for that condition. This caused return "first" to be executed unconditionally.

function compare(a,b) {
    var sum = 0;
    for(var i=0; i<a.length;i++) {
        sum += a[i];
        var avg1 = (sum/a.length);
    }

    var sum2 = 0;
    for(i=0;i<b.length;i++) {
        sum2 += b[i];
        var avg2 = (sum2/b.length);
    }
    if (avg1 > avg2) {
        return "first";
    } else {
        return "second";
    }
}
alert(compare([80, 100], [100, 100]));
alert(compare([100, 150, 200], [50, 75, 100, 110]));

Answer 2

To calculate the average of the elements in arrays a and b, make sure you are summing those elements individually, not from array first.

Moreover, there was a redundant ; after if (avg1 > avg2), which resulted in an empty body for that condition. This caused return "first" to be executed unconditionally.

function compare(a,b) {
    var sum = 0;
    for(var i=0; i<a.length;i++) {
        sum += a[i];
        var avg1 = (sum/a.length);
    }

    var sum2 = 0;
    for(i=0;i<b.length;i++) {
        sum2 += b[i];
        var avg2 = (sum2/b.length);
    }
    if (avg1 > avg2) {
        return "first";
    } else {
        return "second";
    }
}
alert(compare([80, 100], [100, 100]));
alert(compare([100, 150, 200], [50, 75, 100, 110]));

Answer 3

Answer №2

If you're looking for a simpler method...

Check out my response to a similar query on calculating the average of an array using JavaScript.

var avg = myArray.reduce(function(a, b) {
    return a + b;
}) / myArray.length;

You can apply this to both arrays and utilize Math.max() to identify the higher average between them. The combined function would appear as follows:

var highestAvg = function (arr1, arr2) {
    return Math.max( arr1.reduce(function(a, b) {
        return a + b;
    }) / arr1.length, arr2.reduce(function(a, b) {
        return a + b;
    }) / arr2.length );
}

If you prefer to display the original array or terms like "first", then you simply compare the averages:

var greaterAverage = function (arr1, arr2) {
    var avg1 = arr1.reduce(function(a, b) {
        return a + b;
    }) / arr1.length;

    var avg2 = arr2.reduce(function(a, b) {
        return a + b;
    }) / arr2.length;

    if (avg1 < avg2) {
        return avg1; // or return "first";
    } else if (avg1 > avg2) {
        return avg2; // or return "second";
    }
}

Answer 4

If you're looking for a simpler method...

Check out my response to a similar query on calculating the average of an array using JavaScript.

var avg = myArray.reduce(function(a, b) {
    return a + b;
}) / myArray.length;

You can apply this to both arrays and utilize Math.max() to identify the higher average between them. The combined function would appear as follows:

var highestAvg = function (arr1, arr2) {
    return Math.max( arr1.reduce(function(a, b) {
        return a + b;
    }) / arr1.length, arr2.reduce(function(a, b) {
        return a + b;
    }) / arr2.length );
}

If you prefer to display the original array or terms like "first", then you simply compare the averages:

var greaterAverage = function (arr1, arr2) {
    var avg1 = arr1.reduce(function(a, b) {
        return a + b;
    }) / arr1.length;

    var avg2 = arr2.reduce(function(a, b) {
        return a + b;
    }) / arr2.length;

    if (avg1 < avg2) {
        return avg1; // or return "first";
    } else if (avg1 > avg2) {
        return avg2; // or return "second";
    }
}

Answer 5

Answer №3

A more straightforward approach is to clearly define the concept of average.

The average of a set of numbers is calculated by adding all the numbers together and then dividing by the total count of numbers in the set. I have chosen to let an error occur when trying to find the average of an empty set as mathematically, it doesn't make sense. However, some may prefer to handle this situation by returning zero instead.

To calculate the sum of the numbers, you can use the reduce method on the array by adding each element together.

var First  = [1,2,3],
    Second = [3,4,5];

function avg(A) {
    var Total = A.reduce( function(L,R) { return L+R; } );
    return Total / A.length;
}

window.alert( (avg(First) > avg(Second))? 'First' : 'Second' );

Answer 6

A more straightforward approach is to clearly define the concept of average.

The average of a set of numbers is calculated by adding all the numbers together and then dividing by the total count of numbers in the set. I have chosen to let an error occur when trying to find the average of an empty set as mathematically, it doesn't make sense. However, some may prefer to handle this situation by returning zero instead.

To calculate the sum of the numbers, you can use the reduce method on the array by adding each element together.

var First  = [1,2,3],
    Second = [3,4,5];

function avg(A) {
    var Total = A.reduce( function(L,R) { return L+R; } );
    return Total / A.length;
}

window.alert( (avg(First) > avg(Second))? 'First' : 'Second' );

Answer 7

Answer №4

Initially, there was a mistake in your syntax for the if else statement. The correct syntax for the if else statement should look like this:

if (condition) {
    // block of code to be executed if the condition is true
} else { 
    // block of code to be executed if the condition is false
}

For example,

If the time is before 20:00, display a "Good day" greeting; otherwise, show "Good evening":

if (time < 20) {
    greeting = "Good day";
} else {
    greeting = "Good evening";
}

The output will be: Good day.

You can view the corrected code on this jsfiddle link here: Corrected code

Answer 8

Initially, there was a mistake in your syntax for the if else statement. The correct syntax for the if else statement should look like this:

if (condition) {
    // block of code to be executed if the condition is true
} else { 
    // block of code to be executed if the condition is false
}

For example,

If the time is before 20:00, display a "Good day" greeting; otherwise, show "Good evening":

if (time < 20) {
    greeting = "Good day";
} else {
    greeting = "Good evening";
}

The output will be: Good day.

You can view the corrected code on this jsfiddle link here: Corrected code

Calculate the mean value of each array, and then determine which average is higher

Answer №1

Answer №2

Answer №3

Answer №4

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