Method evaluate

datafusion/functions-aggregate/src/variance.rs:387–410

(&mut self)

    }

    fn evaluate(&mut self) -> Result<ScalarValue> {
        let count = match self.stats_type {
            StatsType::Population => self.count,
            StatsType::Sample => {
                if self.count > 0 {
                    self.count - 1
                } else {
                    self.count
                }
            }
        };

        Ok(ScalarValue::Float64(match self.count {
            0 => None,
            1 => {
                if let StatsType::Population = self.stats_type {
                    Some(0.0)
                } else {
                    None
                }
            }
            _ => Some(self.m2 / count as f64),
        }))
    }

    fn size(&self) -> usize {
        size_of_val(self)