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Array

In OmniSciDB, an array has the following internal representation:

typedef struct {
    T* data;  // contiguous memory block
    int64_t size;
    int8 is_null;  // boolean values in omniscidb are represented as int8 variables
} Array;

Creating an Array programmatically

from numba import types as nb_types
from rbc.omnisci_backend import Array

@omnisci('double[](int64)')
def create_array(size):
    array = Array(size, nb_types.double)
    for i in range(size):
        array[i] = nb_types.double(i)
    return array

*Notice that returning an empty array is an invalid operation that might crash the server.

One can also use one of the array creation functions as specified in the python Array API standard: full, full_like, zeros, zeros_like, ones and ones_like:

from numba import types as nb_types
import rbc.omnisci_backend as omni

@omnisci('double[](int64)')
def zero_array(size):
    return omni.zeros(size, nb_types.double)

Accessing a pointer member

@omnisci('double(double[], int64)')
def get_array_member(array, idx):
    return array[idx]

Getting the size of an array

@omnisci('int64(double[])')
def get_array_size(array):
    return len(array)

Checking for null

You can either check if an array is null or if an array value is null

@omnisci('int8(double[])')
def is_array_null(array):
    return array.is_null()

@omnisci('int8(double[], int64)')
def is_array_null(array, idx):
    return array.is_null(idx)