src/Sparkline/StyleTrait.php
protected function paddingStringToArray($padding)
    {
        $parts = explode(' ', $padding);
        switch (count($parts)) {
            case static::CSS_PADDING_ONE:
                $value = (float)$parts[0];

                return [$value, $value, $value, $value];
                break;
            case static::CSS_PADDING_TWO:
                $verticalValue = (float)$parts[0];
                $horizontalValue = (float)$parts[1];

                return [$verticalValue, $horizontalValue, $verticalValue, $horizontalValue];
            case static::CSS_PADDING_THREE:
                $parts[3] = $parts[1];

                return $parts;
            case static::CSS_PADDING:
                return $parts;
            default:
                throw new \InvalidArgumentException('Invalid padding format');
        }
    }
protected function paddingStringToArray($padding)
    {
        $parts = explode(' ', $padding);
        switch (count($parts)) {
            case static::CSS_PADDING_ONE:
                $value = (float)$parts[0];

                return [$value, $value, $value, $value];
                break;
            case static::CSS_PADDING_TWO:
                $verticalValue = (float)$parts[0];
                $horizontalValue = (float)$parts[1];

                return [$verticalValue, $horizontalValue, $verticalValue, $horizontalValue];
            case static::CSS_PADDING_THREE:
                $parts[3] = $parts[1];

                return $parts;
            case static::CSS_PADDING:
                return $parts;
            default:
                throw new \InvalidArgumentException('Invalid padding format');
        }
    }
Formats:
all
vertical horizontal
top horizontal bottom
top right bottom left.

@param string $padding

@return array