yii\i18n\Formatter::createNumberFormatter PHP Method

    protected function createNumberFormatter($style, $decimals = null, $options = [], $textOptions = [])
    {
        $formatter = new NumberFormatter($this->locale, $style);
        // set text attributes
        foreach ($this->numberFormatterTextOptions as $name => $attribute) {
            $formatter->setTextAttribute($name, $attribute);
        }
        foreach ($textOptions as $name => $attribute) {
            $formatter->setTextAttribute($name, $attribute);
        }
        // set attributes
        foreach ($this->numberFormatterOptions as $name => $value) {
            $formatter->setAttribute($name, $value);
        }
        foreach ($options as $name => $value) {
            $formatter->setAttribute($name, $value);
        }
        if ($decimals !== null) {
            $formatter->setAttribute(NumberFormatter::MAX_FRACTION_DIGITS, $decimals);
            $formatter->setAttribute(NumberFormatter::MIN_FRACTION_DIGITS, $decimals);
        }
        // set symbols
        if ($this->decimalSeparator !== null) {
            $formatter->setSymbol(NumberFormatter::DECIMAL_SEPARATOR_SYMBOL, $this->decimalSeparator);
        }
        if ($this->thousandSeparator !== null) {
            $formatter->setSymbol(NumberFormatter::GROUPING_SEPARATOR_SYMBOL, $this->thousandSeparator);
            $formatter->setSymbol(NumberFormatter::MONETARY_GROUPING_SEPARATOR_SYMBOL, $this->thousandSeparator);
        }
        foreach ($this->numberFormatterSymbols as $name => $symbol) {
            $formatter->setSymbol($name, $symbol);
        }
        return $formatter;
    }