IndexError encountered when computing SPI

[jessefriend]

Describe the bug I encountered an "IndexError: index 159 is out of bounds for axis 1 with size 159" when attempting to use the SPI computation function from the climate-indices Python package.

To Reproduce Steps to reproduce the behavior:

1. Installed the climate-indices package in a conda environment.
   

2. Ran the following command:
   

spi --periodicity monthly --scales 1 2 3 6 9 12 24 36 48 --calibration_start_year 1981 --calibration_end_year 2023 --netcdf_precip /path/to/my/netcdf/precip_data.nc --var_name_precip precip --output_file_base /path/to/my/output/CHIRPS --multiprocessing all --save_params /path/to/my/output/CHIRPS_fitting.nc --overwrite

1. Encountered the following error: IndexError: index 159 is out of bounds for axis 1 with size 159

The full traceback is as follows:

multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
  File "/home/user/miniconda3/envs/climate_indices/lib/python3.7/multiprocessing/pool.py", line 121, in worker
    result = (True, func(*args, **kwds))
  File "/home/user/miniconda3/envs/climate_indices/lib/python3.7/multiprocessing/pool.py", line 44, in mapstar
    return list(map(*args))
  File "/home/user/miniconda3/envs/climate_indices/lib/python3.7/site-packages/climate_indices/__spi__.py", line 1212, in _apply_to_subarray_gamma
    periodicity=args["periodicity"],
IndexError: index 159 is out of bounds for axis 1 with size 159
"""
  File "climate_indices/__spi__.py", line 1502, in main
    _compute_write_index(kwrgs)
  File "climate_indices/__spi__.py", line 700, in _compute_write_index
    args=args,
  File "climate_indices/__spi__.py", line 1007, in _parallel_fitting
    pool.map(_apply_to_subarray_gamma, chunk_params)
  File "multiprocessing/pool.py", line 268, in map
    return self._map_async(func, iterable, mapstar, chunksize).get()
  File "multiprocessing/pool.py", line 657, in get
    raise self._value
IndexError: index 159 is out of bounds for axis 1 with size 159

Expected behavior I expected the climate-indices package to compute the SPI without any issues.

Desktop (please complete the following information):

• OS: Ubuntu 22.04.1 LTS
• Version of climate-indices used: latest version from pip

Additional Context I was following this guideline on computing SPI using CHIRPS data.