How Can I call Python module and function in MATLAB script

I am using a python module 'nctoolkit' for some statistical analysis in Jupyter Notebook. I have also a own matlab toolbox for postprocessing. For some reason I want to use nctoolkit methods for statistical analysis in my matlab scrip and also along with getting output in MATLAB, plots the output as well based on my matlab code 'myscript.m'. Thanks if some one can help me how can I do that. please see example;

The below is my python code to plot timeseries,

import nctoolkit as nc
ff1="sst.mon.mean_model.nc"
ds1=nc.open_data(ff1)
ds1.spatial_mean() 
#
ff2="sst.mon.mean_obs.nc"
ds2=nc.open_data(ff2)
ds2.spatial_mean()

I want to use the above code in my matlab script and then plot it as below;

figure
plot(time,ds1)
hole on
plot(time,ds2)
hold off

with time range on x-axis since 1860 20 2021 and sst range on y-axis from 0.5 to 20 oC .

please see attache plot of ds1,

Answer 1

[Hassaan]

Step 1: Ensure Python Compatibility

Versions of Python Compatible with MATLAB Products by Release - MATLAB & Simulink (mathworks.com)

First, ensure MATLAB is configured to use a compatible Python environment. MATLAB needs to know the location of the Python interpreter you're using.

1. Check Python Version: MATLAB supports specific Python versions. Check the MathWorks documentation for the version of MATLAB you are using to ensure compatibility.
2. Configure Python Interpreter: You can set or check the Python interpreter MATLAB is using with the pyenv command in MATLAB.

% Check current Python environment
pyenv

% Set Python environment, replace the path with your Python executable path
pyenv('Version', 'path/to/python');

Step 2: Convert Your Python Code for MATLAB

You can call Python functions directly in MATLAB. Here's how you can adapt your Python code to work within a MATLAB script:

% Assuming you've set up your Python environment in MATLAB as shown above

% Open your datasets using nctoolkit
ds1 = py.nctoolkit.open_data("sst.mon.mean_model.nc");
ds1.spatial_mean();

ds2 = py.nctoolkit.open_data("sst.mon.mean_obs.nc");
ds2.spatial_mean();

% Convert Python objects to MATLAB arrays if needed
% This step depends on the data structure returned by your Python code
% For the sake of example, let's assume ds1 and ds2 have a method to return data as NumPy arrays
% MATLAB can automatically convert NumPy arrays to MATLAB arrays
ds1_data = double(ds1.to_numpy()); % Convert Python's NumPy array to MATLAB array
ds2_data = double(ds2.to_numpy());

% Define your time range
time = 1860:2021; % Adjust based on your actual data

% Plot your data
figure;
plot(time, ds1_data);
hold on;
plot(time, ds2_data);
hold off;

% Set the axis limits and labels
xlim([1860 2021]);
ylim([0.5 20]);
xlabel('Time');
ylabel('SST (°C)');
title('SST Time Series');

Notes:

• Data Conversion: When transferring data between Python and MATLAB, ensure that the data types are compatible. MATLAB automatically handles many common data types (e.g., numbers, strings, arrays), but complex structures may require manual conversion.
• Error Handling: MATLAB will throw an error if there's an issue with the Python code execution. Ensure your Python environment has nctoolkit installed and is properly configured.
• Plotting: The plotting code in MATLAB (plot) assumes ds1 and ds2 can be directly plotted against time. This example assumes your Python code (ds1.spatial_mean(), ds2.spatial_mean()) results in data that can be plotted this way. You may need to adjust how you extract data from the ds1 and ds2 objects based on nctoolkit's actual data structure.

Depending on the complexity and specific requirements of your project, further adjustments might be necessary.

References

Versions of Python Compatible with MATLAB Products by Release - MATLAB & Simulink (mathworks.com)

Call Python from MATLAB - MATLAB & Simulink (mathworks.com)

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