Method unary_opt

arrow-array/src/array/primitive_array.rs:1044–1082

Applies a unary and nullable function to all valid values in a primitive array Applies `op` to only rows that are valid, which is often significantly slower than [`Self::unary`], which should be preferred if `op` is fallible. Note: LLVM is currently unable to effectively vectorize fallible operations

(&self, op: F)

    ///
    /// Note: LLVM is currently unable to effectively vectorize fallible operations
    pub fn unary_opt<F, O>(&self, op: F) -> PrimitiveArray<O>
    where
        O: ArrowPrimitiveType,
        F: Fn(T::Native) -> Option<O::Native>,
    {
        let len = self.len();
        let (nulls, null_count, offset) = match self.nulls() {
            Some(n) => (Some(n.validity()), n.null_count(), n.offset()),
            None => (None, 0, 0),
        };

        let mut null_builder = BooleanBufferBuilder::new(len);
        match nulls {
            Some(b) => null_builder.append_packed_range(offset..offset + len, b),
            None => null_builder.append_n(len, true),
        }

        let mut buffer = BufferBuilder::<O::Native>::new(len);
        buffer.append_n_zeroed(len);
        let slice = buffer.as_slice_mut();

        let mut out_null_count = null_count;

        let _ = try_for_each_valid_idx(len, offset, null_count, nulls, |idx| {
            match op(unsafe { self.value_unchecked(idx) }) {
                Some(v) => unsafe { *slice.get_unchecked_mut(idx) = v },
                None => {
                    out_null_count += 1;
                    null_builder.set_bit(idx, false);
                }
            }
            Ok::<_, ()>(())
        });

        let nulls = null_builder.finish();
        let values = buffer.finish().into();
        let nulls = unsafe { NullBuffer::new_unchecked(nulls, out_null_count) };
        PrimitiveArray::new(values, Some(nulls))
    }

    /// Applies a unary infallible function to each value in an array, producing a
    /// new primitive array.