ilStatistics Class Reference

Constants for the handling of elements which are not a number. More...

Collaboration diagram for ilStatistics:

Public Member Functions
	setData (array $stat_data)
	getData ()
	min ()
	max ()
	Calculates the maximum value. More...
	count ()
	Calculates number of data values. More...
	sum_n (int $n)
	Calculates the sum of x_1^n + x_2^n + ... More...
	sum ()
	Calculates the sum of x_1 + x_2 + ... More...
	sum2 ()
	Calculates the sum of x_1^2 + x_2^2 + ... More...
	product_n (int $n)
	Calculates the product of x_1^n * x_2^n * ... More...
	product (int $n)
	Calculates the product of x_1 * x_2 * ... More...
	arithmetic_mean ()
	Arithmetic mean of the data values xbar = (1/n)*∑x_i. More...
	geometric_mean ()
	Geometric mean of the data values geometric_mean = (x_1 * x_2 * ... More...
	harmonic_mean ()
	Harmonic mean of the data values harmonic_mean = n/(1/x_1 + 1/x_2 + ... More...
	median ()
	Median of the data values. More...
	rank (float $value)
	Returns the rank of a given value. More...
	rank_median ()
	Returns the rank of the median. More...
	quantile (float $n)
	n-Quantile of the data values More...

Data Fields
array	$stat_data = []

Private Member Functions
	removeNonNumericValues ()

Detailed Description

Constants for the handling of elements which are not a number.

This class provides mathematical functions for statistics. It works on an array of numeric values.

Author

Helmut Schottmüller hscho.nosp@m.ttm@.nosp@m.tzi.d.nosp@m.e

Version

$Id$

Definition at line 33 of file class.ilStatistics.php.

Member Function Documentation

arithmetic_mean()

ilStatistics::arithmetic_mean

(

)

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

Definition at line 142 of file class.ilStatistics.php.

References count(), and sum().

                                     : ?float
    {
        $sum = $this->sum();
        if ($sum === null) {
            return null;
        }

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

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count()

ilStatistics::count

(

)

Calculates number of data values.

Definition at line 72 of file class.ilStatistics.php.

Referenced by arithmetic_mean(), geometric_mean(), harmonic_mean(), median(), quantile(), rank(), and rank_median().

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

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geometric_mean()

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.

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

References count(), and product().

                                    : ?float
    {
        $prod = $this->product(1);
        if (($prod === null) || ($prod === 0)) {
            return null;
        }
        $count = $this->count();
        if ($count === 0) {
            return null;
        }
        return pow((float) $prod, (float) (1 / $count));
    }

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getData()

ilStatistics::getData

(

)

Definition at line 43 of file class.ilStatistics.php.

References $stat_data.

                             : array
    {
        return $this->stat_data;
    }

harmonic_mean()

ilStatistics::harmonic_mean

(

)

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

• 1/x_n)

Definition at line 181 of file class.ilStatistics.php.

References count(), and min().

                                   : ?float
    {
        $min = $this->min();
        if (($min === null) or ($min === 0)) {
            return null;
        }
        $count = $this->count();
        if ($count === 0) {
            return null;
        }
        $sum = 0.0;
        foreach ($this->stat_data as $value) {
            $sum += 1 / $value;
        }
        return $count / $sum;
    }

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max()

ilStatistics::max

(

)

Calculates the maximum value.

Definition at line 60 of file class.ilStatistics.php.

                         : ?float
    {
        if ($this->stat_data === []) {
            return null;
        }

        return max($this->stat_data);
    }

median()

ilStatistics::median

(

)

Median of the data values.

Definition at line 201 of file class.ilStatistics.php.

References count().

                            : ?float
    {
        if ($this->stat_data === null) {
            return null;
        }

        $median = 0.0;
        $count = $this->count();
        if ((count($this->stat_data) % 2) === 0) {
            return ($this->stat_data[($count / 2) - 1] + $this->stat_data[($count / 2)]) / 2;
        }

        return $this->stat_data[(($count + 1) / 2) - 1];
    }

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min()

ilStatistics::min

(

)

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

Referenced by harmonic_mean(), and product_n().

                         : ?float
    {
        if ($this->stat_data === []) {
            return null;
        }

        return min($this->stat_data);
    }

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product()

ilStatistics::product

(

int

$n

)

Calculates the product of x_1 * x_2 * ...

• x_i

Definition at line 133 of file class.ilStatistics.php.

References product_n().

Referenced by geometric_mean().

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

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product_n()

ilStatistics::product_n

(

int

$n

)

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

• x_i^n

Definition at line 113 of file class.ilStatistics.php.

References min().

Referenced by product().

                                     : ?float
    {
        if ($this->stat_data === []) {
            return null;
        }

        if ($this->min() === 0) {
            return 0.0;
        }

        $prod_n = 1.0;
        foreach ($this->stat_data as $value) {
            $prod_n *= pow((float) $value, (float) $n);
        }
        return $prod_n;
    }

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quantile()

ilStatistics::quantile

(

float

$n

)

n-Quantile of the data values

Definition at line 253 of file class.ilStatistics.php.

References count(), and ILIAS\Repository\int().

                                      : ?float
    {
        $count = $this->count();
        if ($count === 0) {
            return null;
        }

        $nprod = ($n / 100) * $count;
        if (intval($nprod) != $nprod) {
            return $this->stat_data[ceil($nprod) - 1];
        }

        if ($nprod === 0.0) {
            return $this->stat_data[0];
        }

        if ($nprod === (float) $count) {
            return $this->stat_data[(int) $nprod - 1];
        }

        return ($this->stat_data[(int) $nprod - 1] + $this->stat_data[(int) $nprod]) / 2;
    }

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rank()

ilStatistics::rank

(

float

$value

)

Returns the rank of a given value.

Definition at line 219 of file class.ilStatistics.php.

References count().

                                      : ?int
    {
        $rank = array_search($value, $this->stat_data);
        if ($rank === false) {
            return null;
        }

        return $this->count() - $rank;
    }

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rank_median()

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.

Definition at line 236 of file class.ilStatistics.php.

References count().

                                 : ?float
    {
        $count = $this->count();
        if ($count === 0) {
            return null;
        }

        if (($count % 2) === 0) {
            return $rank_median = ($count + 1) / 2;
        }

        return $rank_median = ($count + 1) / 2;
    }

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removeNonNumericValues()

ilStatistics::removeNonNumericValues ( )

private

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

References ILIAS\LTI\ToolProvider\$key.

Referenced by setData().

                                             : void
    {

        foreach ($this->stat_data as $key => $value) {
            if (!is_numeric($value)) {
                unset($this->stat_data[$key]);
                break;
            }
        }
        sort($this->stat_data);
    }

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setData()

ilStatistics::setData

(

array

$stat_data

)

Definition at line 37 of file class.ilStatistics.php.

References removeNonNumericValues().

                                             : void
    {
        $this->stat_data = array_values($stat_data);
        $this->removeNonNumericValues();
    }

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sum()

ilStatistics::sum

(

)

Calculates the sum of x_1 + x_2 + ...

• x_i

Definition at line 96 of file class.ilStatistics.php.

References sum_n().

Referenced by arithmetic_mean().

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

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sum2()

ilStatistics::sum2

(

)

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

• x_i^2

Definition at line 105 of file class.ilStatistics.php.

References sum_n().

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

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sum_n()

ilStatistics::sum_n

(

int

$n

)

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

• x_i^n

Definition at line 80 of file class.ilStatistics.php.

Referenced by sum(), and sum2().

                                 : ?float
    {
        if ($this->stat_data === []) {
            return null;
        }

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

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Field Documentation

$stat_data

array ilStatistics::$stat_data = []

Definition at line 35 of file class.ilStatistics.php.

Referenced by getData().

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

• Modules/Test/classes/class.ilStatistics.php