Preallocating 2D arrays in a Numba class - python-3.x

Question

I am working on a class speedup with Numba. When you want to use Numba inside classes you have to define/preallocate your class variables. In this respect my issue is declaring a 2D array before the jitclass. The following MWE directly shows my issue:
import numpy as np
from numba import int32, float32
from numba.experimental import jitclass # import the decorator
spec = [
('value', int32), # a simple scalar field
('array', float32[:]), # an array field
('foo_matrix',int32[:,:]),
]
#jitclass(spec)
class Bag(object):
def __init__(self, value):
self.value = value
self.array = np.zeros(value)
self.foo_matrix = np.zeros((value, value))
#property
def size(self):
return self.array.size
def increment(self, val):
for i in range(self.size):
self.array[i] = val
return self.array
my_class = Bag(3)
When I execute this code I get the following error:
Traceback (most recent call last):
File "/home/acer/codici/tech/numba_prototype.py", line 38, in <module>
my_class = Bag(3)
File "/usr/lib/python3/dist-packages/numba/experimental/jitclass/base.py", line 122, in __call__
return cls._ctor(*bind.args[1:], **bind.kwargs)
File "/usr/lib/python3/dist-packages/numba/core/dispatcher.py", line 414, in _compile_for_args
error_rewrite(e, 'typing')
File "/usr/lib/python3/dist-packages/numba/core/dispatcher.py", line 357, in error_rewrite
raise e.with_traceback(None)
numba.core.errors.TypingError: Failed in nopython mode pipeline (step: nopython frontend)
Internal error at <numba.core.typeinfer.CallConstraint object at 0x7fc6d4945c40>.
Failed in nopython mode pipeline (step: nopython mode backend)
Can only insert float* at [4] in {i8*, i8*, i64, i64, float*, [1 x i64], [1 x i64]}: got double*
File "numba_prototype.py", line 19:
def __init__(self, value):
<source elided>
self.value = value
self.array = np.zeros(value)
^
During: lowering "(self).array = $14call_method.5" at /home/acer/codici/tech/numba_prototype.py (19)
During: resolving callee type: jitclass.Bag#7fc6d5a2afa0<value:int32,array:array(float32, 1d, A),foo_matrix:array(int32, 2d, A)>
During: typing of call at <string> (3)
Enable logging at debug level for details.
File "<string>", line 3:
<source missing, REPL/exec in use?>
which is related to the declaration of the matrix foo_matrix.
Concerning the types definition I followed this.
Of course if I comment out the lines about array declaration and population the code works fine.
How should I modify/do the declaration of the matrix with respect to a jitclass object?
EDIT: inside the class, I have changed the declaration of foo_matrix from np.zeros([value, value]) to np.zeros((value, value)) since defining a numpy array using a list instead of a tuple may be a source of error for numba functions. However the problem persists even with this modification.

Answer 1

The error is due to the fact that in the zeros array and matrix there is no the type specification i.e. : self.array = np.zeros(value, dtype=np.float32).
The working code is the following:
import numpy as np
from numba import int32, float32
from numba.experimental import jitclass
spec = [
('value', int32),
('array', float32[:]),
('foo_matrix',int32[:,:]),
]
#jitclass(spec)
class Bag(object):
def __init__(self, value):
self.value = value
self.array = np.zeros(value, dtype=np.float32)
self.foo_matrix = np.zeros((value, value), dtype=np.int32)
alice = value +1
bob = np.sum(self.array)
#property
def size(self):
return self.array.size
def increment(self, val):
for i in range(self.size):
self.array[i] = val
return self.array
my_class = Bag(3)