Function zip

pub fn zip(
    mask: &BooleanArray,
    truthy: &dyn Datum,
    falsy: &dyn Datum,
) -> Result<Arc<dyn Array>, ArrowError>

Zip two arrays by some boolean mask.

• Where mask is true, values of truthy are taken
• Where mask is false or NULL, values of falsy are taken

Example: zip two arrays

// mask: [true, true, false, NULL, true]
let mask = BooleanArray::from(vec![
  Some(true), Some(true), Some(false), None, Some(true)
]);
// truthy array: [1, NULL, 3, 4, 5]
let truthy = Int32Array::from(vec![
  Some(1), None, Some(3), Some(4), Some(5)
]);
// falsy array: [10, 20, 30, 40, 50]
let falsy = Int32Array::from(vec![
  Some(10), Some(20), Some(30), Some(40), Some(50)
]);
// zip with this mask select the first, second and last value from `truthy`
// and the third and fourth value from `falsy`
let result = zip(&mask, &truthy, &falsy).unwrap();
// Expected: [1, NULL, 30, 40, 5]
let expected: ArrayRef = Arc::new(Int32Array::from(vec![
  Some(1), None, Some(30), Some(40), Some(5)
]));
assert_eq!(&result, &expected);

Example: zip and array with a scalar

Use zip to replace certain values in an array with a scalar

// mask: [true, true, false, NULL, true]
let mask = BooleanArray::from(vec![
  Some(true), Some(true), Some(false), None, Some(true)
]);
//  array: [1, NULL, 3, 4, 5]
let arr = Int32Array::from(vec![
  Some(1), None, Some(3), Some(4), Some(5)
]);
// scalar: 42
let scalar = Int32Array::new_scalar(42);
// zip the array with the  mask select the first, second and last value from `arr`
// and fill the third and fourth value with the scalar 42
let result = zip(&mask, &arr, &scalar).unwrap();
// Expected: [1, NULL, 42, 42, 5]
let expected: ArrayRef = Arc::new(Int32Array::from(vec![
  Some(1), None, Some(42), Some(42), Some(5)
]));
assert_eq!(&result, &expected);