Configure the python environment

The code for calculating SPI and SPEI are written in Python 3. It is recommended to use either the Miniconda3 (minimal Anaconda) or Anaconda3 distribution. The below instructions will be Anaconda specific (although relevant to any Python virtual environment), and assume the use of a bash shell.

A new Anaconda environment can be created using the conda environment management system that comes packaged with Anaconda. In the following examples, I’ll use an environment named climate_indices (any environment name can be used instead of climate_indices) which will be created and populated with all required dependencies through the use of the provided setup.py file.

This step must only be done the first time. Once the environment has been created there is no need to do it again.

Create new python environment

First, open your Terminal (in your macOS/Linux and Ubuntu Linux on WSL), create the Python environment with python3.7 as default:
```
conda create -n climate_indices python=3.7
```
Proceed with y
The environment created can now be ‘activated’:
```
conda activate climate_indices
```

Install python package and additional software

Install climate-indices package. Once the environment has been activated then subsequent Python commands will run in this environment where the package dependencies for this project are present. Now the package can be added to the environment along with all required modules (dependencies) via pip:
```
pip install climate-indices
```
Install netCDF Operator (NCO), Climate Data Operator (CDO) from Max-Planck-Institut für Meteorologie and Geospatial Data Abstraction Library (GDAL/OGR) using conda and proceed with y.
```
conda install -c conda-forge nco cdo gdal
```