ilStatistics Class Reference

Collaboration diagram for ilStatistics:

Public Member Functions
	ilStatistics ($nan_handling=NAN_HANDLING_REMOVE)
	Constructor of ilStatistics class.
	setNANHandling ($nan_handling=NAN_HANDLING_REMOVE)
	Set the handling of elements which are not a number.
	getNANHandling ()
	Get the handling of elements which are not a number.
	setData ($stat_data)
	Sets the data and checks for invalid values.
	getData ()
	Returns the numeric value array containing the data.
	min ()
	Calculates the minimum value.
	max ()
	Calculates the maximum value.
	count ()
	Calculates number of data values.
	sum_n ($n)
	Calculates the sum of x_1^n + x_2^n + ...
	sum ()
	Calculates the sum of x_1 + x_2 + ...
	sum2 ()
	Calculates the sum of x_1^2 + x_2^2 + ...
	product_n ($n)
	Calculates the product of x_1^n * x_2^n * ...
	product ($n)
	Calculates the product of x_1 * x_2 * ...
	arithmetic_mean ()
	Arithmetic mean of the data values xbar = (1/n)*∑x_i.
	geometric_mean ()
	Geometric mean of the data values geometric_mean = (x_1 * x_2 * ...
	harmonic_mean ()
	Harmonic mean of the data values harmonic_mean = n/(1/x_1 + 1/x_2 + ...
	median ()
	Median of the data values.
	rank ($value)
	Returns the rank of a given value.
	rank_median ()
	Returns the rank of the median.
	quantile ($n)
	n-Quantile of the data values
	validate ()
	Validates the numeric data and handles values which are not a number according to the $nan_handling variable.

Data Fields
	$nan_handling
	$stat_data

Detailed Description

Definition at line 38 of file class.ilStatistics.php.

Member Function Documentation

ilStatistics::arithmetic_mean

(

)

Arithmetic mean of the data values xbar = (1/n)*∑x_i.

Returns

mixed The arithmetic mean or false, if there is an error or no values public

Definition at line 251 of file class.ilStatistics.php.

References count(), and sum().

                                   {
                $sum = $this->sum();
                if ($sum === false)
                {
                        return false;
                }
                $count = $this->count();
                if ($count == 0)
                {
                        return false;
                }
                return (double)($sum/$count);
        }

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ilStatistics::count

(

)

Calculates number of data values.

Returns

mixed The number of data values public

Definition at line 164 of file class.ilStatistics.php.

Referenced by arithmetic_mean(), geometric_mean(), harmonic_mean(), max(), median(), min(), product_n(), quantile(), rank(), rank_median(), and sum_n().

                         {
                return count($this->stat_data);
        }

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ilStatistics::geometric_mean

(

)

Geometric mean of the data values geometric_mean = (x_1 * x_2 * ...

• x_n)^(1/n)

The geometric mean of a set of positive data is defined as the product of all the members of the set, raised to a power equal to the reciprocal of the number of members.

Returns

mixed The geometric mean or false, if there is an error or no values public

Definition at line 276 of file class.ilStatistics.php.

References count(), and product().

                                  {
                $prod = $this->product();
                if (($prod === false) or ($prod === 0))
                {
                        return false;
                }
                $count = $this->count();
                if ($count == 0)
                {
                        return false;
                }
                return pow((double)$prod, (double)(1/$count));
        }

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ilStatistics::getData

(

)

Returns the numeric value array containing the data.

Returns

array An array containing the sorted numeric data public

Definition at line 115 of file class.ilStatistics.php.

References $stat_data.

        {
                return $this->stat_data;
        }

ilStatistics::getNANHandling

(

)

Get the handling of elements which are not a number.

Returns NAN_HANDLING_REMOVE if all elements which are not a number will be removed. Returns NAN_HANDLING_ZERO if all elements which are not a number will be set to zero.

Returns

integer A constant defining the handling of elements which are not a number public

Definition at line 92 of file class.ilStatistics.php.

References $nan_handling.

        {
                return $this->nan_handling;
        }

ilStatistics::harmonic_mean

(

)

Harmonic mean of the data values harmonic_mean = n/(1/x_1 + 1/x_2 + ...

• 1/x_n)

Returns

mixed The harmonic mean or false, if there is an error or no values public

Definition at line 297 of file class.ilStatistics.php.

References count(), and min().

                                 {
                $min = $this->min();
                if (($min === false) or ($min === 0))
                {
                        return false;
                }
                $count = $this->count();
                if ($count == 0)
                {
                        return false;
                }
                $sum = 0;
                foreach ($this->stat_data as $value)
                {
                        $sum += 1/$value;
                }
                return $count/$sum;
        }

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ilStatistics::ilStatistics

(

$nan_handling = NAN_HANDLING_REMOVE

)

Constructor of ilStatistics class.

public

Definition at line 63 of file class.ilStatistics.php.

References $nan_handling.

        {
                $this->nan_handling = $nan_handling;
                $this->stat_data = array();
        }

ilStatistics::max

(

)

Calculates the maximum value.

Returns

mixed The maximum value or false, if no maximum exists

See Also

min() Public

Definition at line 146 of file class.ilStatistics.php.

References count().

                       {
                if (count($this->stat_data))
                {
                        $max = max($this->stat_data);
                }
                else
                {
                        $max = false;
                }
                return $max;
        }

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ilStatistics::median

(

)

Median of the data values.

Returns

mixed The median or false, if there are no data values public

Definition at line 322 of file class.ilStatistics.php.

References count().

                          {
                $median = false;
                if (count($this->stat_data))
                {
                        $median = 0;
                        $count = $this->count();
                        if ((count($this->stat_data) % 2) == 0)
                        {
                                $median = ($this->stat_data[($count / 2) - 1] + $this->stat_data[($count / 2)]) / 2;
                        }
                        else
                        {
                                $median = $this->stat_data[(($count + 1) / 2) - 1];
                        }
                }
                return $median;
        }

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ilStatistics::min

(

)

Calculates the minimum value.

Returns

mixed The minimum value or false, if no minimum exists

See Also

max() Public

Definition at line 127 of file class.ilStatistics.php.

References count().

Referenced by harmonic_mean(), and product_n().

                       {
                if (count($this->stat_data))
                {
                        $min = min($this->stat_data);
                }
                else
                {
                        $min = false;
                }
                return $min;
        }

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ilStatistics::product

(

$n

)

Calculates the product of x_1 * x_2 * ...

• x_i

Parameters

numeric

$n

The exponent

Returns

mixed The product of x_1 * x_2 * ... * x_i or false, if no values exist public

Definition at line 240 of file class.ilStatistics.php.

References product_n().

Referenced by geometric_mean().

                             {
                return $this->product_n(1);
        }

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ilStatistics::product_n

(

$n

)

Calculates the product of x_1^n * x_2^n * ...

• x_i^n

Parameters

numeric

$n

The exponent

Returns

mixed The product of x_1^n * x_2^n * ... * x_i^n or false, if no values exist public

Definition at line 216 of file class.ilStatistics.php.

References $n, count(), and min().

Referenced by product().

                               {
                $prod_n = false;
                if (count($this->stat_data))
                {
                        if ($this->min() === 0)
                        {
                                return 0.0;
                        }
                        $prod_n = 1.0;
                        foreach ($this->stat_data as $value)
                        {
                                $prod_n *= pow((double)$value, (double)$n);
                        }
                }
                return $prod_n;
        }

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ilStatistics::quantile

(

$n

)

n-Quantile of the data values

Parameters

double

$n

A value between 0 an 100 calculating the n-Quantile

Returns

mixed The n-quantile or false, if there are no data values public

Definition at line 396 of file class.ilStatistics.php.

References $n, and count().

                              {
                $count = $this->count();
                if ($count == 0)
                {
                        return false;
                }
                $nprod = ($n/100)*$count;
                if (intval($nprod) == $nprod)
                {
                        $k = $nprod;
                        if ($k == 0)
                        {
                                return $this->stat_data[$k];
                        }
                        else if ($k == $count)
                        {
                                return $this->stat_data[$k-1];
                        }
                        else
                        {
                                return ($this->stat_data[$k-1] + $this->stat_data[$k])/2;
                        }
                }
                else
                {
                        $k = ceil($nprod);
                        return $this->stat_data[$k-1];
                }
        }

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ilStatistics::rank

(

$value

)

Returns the rank of a given value.

Returns

mixed The rank, if the value exists in the data, otherwise false public

Definition at line 346 of file class.ilStatistics.php.

References count().

        {
                if (!is_numeric($value))
                {
                        return false;
                }
                $rank = array_search($value, $this->stat_data);
                if ($rank !== FALSE)
                {
                        $rank = $this->count() - $rank;
                }
                return $rank;
        }

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ilStatistics::rank_median

(

)

Returns the rank of the median.

This method is different from the rank method because the median could be the arithmetic mean of the two middle values when the data size is even. In this case the median could a value which is not part of the data set.

Returns

mixed The rank of the median, otherwise false public

Definition at line 370 of file class.ilStatistics.php.

References count().

        {
                $count = $this->count();
                if ($count == 0)
                {
                        return false;
                }
                
                if (($count % 2) == 0)
                {
                        $rank_median = ($count + 1) / 2;
                }
                else
                {
                        $rank_median = ($count + 1) / 2;
                }
                return $rank_median;
        }

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ilStatistics::setData

(

$stat_data

)

Sets the data and checks for invalid values.

Parameters

array

$stat_data

An array containing the numeric data public

Definition at line 103 of file class.ilStatistics.php.

References $stat_data, and validate().

        {
                $this->stat_data = array_values($stat_data);
                $this->validate();
        }

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ilStatistics::setNANHandling

(

$nan_handling = NAN_HANDLING_REMOVE

)

Set the handling of elements which are not a number.

If set to NAN_HANDLING_REMOVE, all elements which are not a number will be removed, if set to NAN_HANDLING_ZERO, all elements which are not a number will be set to zero.

Parameters

integer

$nan_handling

A constant defining the handling of elements which are not a number public

Definition at line 78 of file class.ilStatistics.php.

References $nan_handling.

        {
                $this->nan_handling = $nan_handling;
        }

ilStatistics::sum

(

)

Calculates the sum of x_1 + x_2 + ...

• x_i

Returns

mixed The sum of x_1 + x_2 + ... + x_i or false, if no values exist public

Definition at line 194 of file class.ilStatistics.php.

References sum_n().

Referenced by arithmetic_mean().

                       {
                return $this->sum_n(1);
        }

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ilStatistics::sum2

(

)

Calculates the sum of x_1^2 + x_2^2 + ...

• x_i^2

Returns

mixed The sum of x_1^2 + x_2^2 + ... + x_i^2 or false, if no values exist public

Definition at line 205 of file class.ilStatistics.php.

References sum_n().

                        {
                return $this->sum_n(2);
        }

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ilStatistics::sum_n

(

$n

)

Calculates the sum of x_1^n + x_2^n + ...

• x_i^n

Parameters

numeric

$n

The exponent

Returns

mixed The sum of x_1^n + x_2^n + ... + x_i^n or false, if no values exist public

Definition at line 175 of file class.ilStatistics.php.

References $n, and count().

Referenced by sum(), and sum2().

                           {
                $sum_n = false;
                if (count($this->stat_data))
                {
                        $sum_n = 0;
                        foreach ($this->stat_data as $value)
                        {
                                $sum_n += pow((double)$value, (double)$n);
                        }
                }
                return $sum_n;
        }

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ilStatistics::validate

(

)

Validates the numeric data and handles values which are not a number according to the $nan_handling variable.

After validation the data is sorted.

Returns

boolean Returns true on success, otherwise false private

Definition at line 434 of file class.ilStatistics.php.

References $result, NAN_HANDLING_REMOVE, and NAN_HANDLING_ZERO.

Referenced by setData().

        {
                $result = true;
                foreach ($this->stat_data as $key => $value)
                {
                        if (!is_numeric($value)) {
                                switch ($this->nan_handling) {
                                        case NAN_HANDLING_REMOVE:
                                                unset($this->stat_data[$key]);
                                                break;
                                        case NAN_HANDLING_ZERO:
                                                $this->stat_data[$key] = 0;
                                                break;
                                        default:
                                                $result = false;
                                }
                        }
                }
                sort($this->stat_data);
                return $result;
        }

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Field Documentation

ilStatistics::$nan_handling

Definition at line 48 of file class.ilStatistics.php.

Referenced by getNANHandling(), ilStatistics(), and setNANHandling().

ilStatistics::$stat_data

Definition at line 56 of file class.ilStatistics.php.

Referenced by getData(), and setData().

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The documentation for this class was generated from the following file:

• classes/class.ilStatistics.php