Mapping the 2D array of burn days to a True/False voxelspace

voxelproblem.py

# Plain for loops
import numpy as np
for j in range(one_month_data.shape[1]):
    for i in range(one_month_data.shape[0]):
        if not np.isnan(one_month_data[i,j]):
            voxelspace[int(one_month_data[i,j]), i, j] = True if one_month_data[i,j] > 0 else False
        elif np.isnan(one_month_data[i,j]);
            date_start, date_end = get_dates_for_current_month()  # return integers
            voxelspace[date_start:date_end, i, j] = np.nan
        elif one_month_data[i,j] == 0;
            date_start, date_end = get_dates_for_current_month()
            voxelspace[date_start:date_end, i, j] = False

# Cythonised version
import cython
cimport numpy
from libc.math cimport isnan

cdef float NAN 
NAN = float("NaN")

# Or use a NoData vlue
cdef int NoData = -9999

# set up ctypes for the variables in the function to allow it to cythonise nicely
cdef int i = 0
cdef int j = 0

cdef int jmax = one_month_data.shape[1]
cdef int imax = one_month_data.shape[0]

# Best to turn off these decorators if you are debugging
# (Segfaults etc.)
@cython.boundscheck(False)
@cython.wraparound(False)
@cython.nonecheck(False)
def voxelspace(np.ndarray[DTYPE_t, ndim=3] voxelspace, np.ndarray[DTYPE_t, ndim=2] one_month_data, MORE_ARGS...):
    for j in range(jmax):
        for i in range(imax):
            if not isnan(one_month_data[i,j]):
                voxelspace[int(one_month_data[i,j]), i, j] = True if one_month_data[i,j] > 0 else False
            elif np.isnan(one_month_data[i,j]);
                date_start, date_end = get_dates_for_current_month()  # return C-type integers from this function
                voxelspace[date_start:date_end, i, j] = NAN  # Or NoData value
            elif one_month_data[i,j] == 0;
                date_start, date_end = get_dates_for_current_month()
                voxelspace[date_start:date_end, i, j] = False
    return voxelspace

def get_dates_for_current_month(month):
    #...code here
    cdef int start_date
    cdef int end_date
    # More code....
    return start_date, end_date

# Add in later paralelism once working:
with nogil, parallel(num_threads=num_threads_use):
    # OpenMP threads created for the outer loop.
    for i in prange(jmax):
        # etc......

@DTMilodowski points out np.isfinite would get rid of the is not formation 👍