216 lines
4.9 KiB
Markdown
216 lines
4.9 KiB
Markdown
# Running Python remotely from Matlab
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{:.no_toc}
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<nav markdown="1" class="toc-class">
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* TOC
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{:toc}
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</nav>
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## The goal
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We want to integrate Python files and code into our Matlab workflow.
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Questions to [David Rotermund](mailto:davrot@uni-bremen.de)
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## Check if you are ready
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[Versions of Python Compatible with MATLAB Products by Release](https://de.mathworks.com/support/requirements/python-compatibility.html)
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You need to ask yourself or better Matlab if it is using the correct Python. You can check this via:
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```matlab
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>> pyenv
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ans =
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PythonEnvironment with properties:
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Version: "3.11"
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Executable: "/data_1/davrot/P3.11/bin/python3"
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Library: "libpython3.11.so.1.0"
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Home: "/data_1/davrot/P3.11"
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Status: NotLoaded
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ExecutionMode: InProcess
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```
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If this is wrong (which it isn't in my case) then you can change it (temporarily?) with
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```matlab
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>> pyenv('Version','/data_1/davrot/P3.11/bin/python3')
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ans =
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PythonEnvironment with properties:
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Version: "3.11"
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Executable: "/data_1/davrot/P3.11/bin/python3"
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Library: "libpython3.11.so.1.0"
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Home: "/data_1/davrot/P3.11"
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Status: NotLoaded
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ExecutionMode: InProcess
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```
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**Obviously you need to use your location for your Python installation.**
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## Python help
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```matlab
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>> py.help('int')
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Help on class int in module builtins:
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class int(object)
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| int([x]) -> integer
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| int(x, base=10) -> integer
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[...]
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```
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## Tuple and random number example
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We can crate a python tuple like this:
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```matlab
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>> py_dim = py.tuple({py.int(10), py.int(100)})
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py_dim =
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Python tuple with values:
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(10, 100)
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Use string, double or cell function to convert to a MATLAB array.
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```
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Now we can use numpy to generate random numbers:
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```matlab
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>> py_dim = py.tuple({py.int(10), py.int(100)})
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>> rng = py.numpy.random.default_rng();
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>> a = rng.random(py_dim);
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>> py.print(py.type(a))
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<class 'numpy.ndarray'>
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>> py.print(a.shape)
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(10, 100)
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>> py.print(a.dtype)
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float64
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>> whos
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>> whos
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Name Size Bytes Class Attributes
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a 1x1 8 py.numpy.ndarray
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ans 1x1 8 matlab.pyclient.PythonEnvironment
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py_dim 1x2 8 py.tuple
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rng 1x1 8 py.numpy.random._generator.Generator
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```
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Alternatively this is also possible:
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```matlab
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>> b = rng.random(cell({int32(10),int32(100)}));
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```
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## User defined Python modules
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Our very own Python function in the file **mtest_1.py**:
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```python
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import numpy as np
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def mysquared(input:np.ndarray) -> np.ndarray:
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output = input**2
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return output
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```
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Now Matlab allows us to do this:
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```matlab
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>> x = (1:1:10);
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>> x_np = py.numpy.array(x);
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>> y_np = py.mtest_1.mysquared(x_np);
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>> y = double(x_np).^2;
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>> sum(sum(abs(y-double(y_np))))
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ans =
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0
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```
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If you change the py file, then you need to clean it from the memory via
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```matlab
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>> clear classes
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```
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Future David here: Well, I had to do this for a file gauss_smear.py with a function gauss_smear:
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```matlab
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if ~exist('mod', 'var')
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mod = py.importlib.import_module('gauss_smear');
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end
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py.importlib.reload(mod);
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clearvars -except mod
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mod.gauss_smear(2.0, 0.1)
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```
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## Save a numpy file with Matlab
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In Matlab we save data into numpy file:
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```matlab
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>> a = rand(100,10);
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>> a_np = py.numpy.array(a);
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>> py.numpy.save("test_1.npy",a_np);
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```
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Now we can load it into Python:
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```python
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import numpy as np
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a = np.load("test_1.npy")
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print(type(a)) # --> <class 'numpy.ndarray'>
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print(a.shape) # --> (100, 10)
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print(a.dtype) # --> float64
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```
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## Loading a numpy file with Matlab
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Under Python we generate a file:
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```python
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import numpy as np
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myrng = np.random.default_rng()
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a = myrng.random((100, 10))
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np.save("test_2.npy", a)
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```
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And under Matlab we load it:
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```matlab
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>> a_np = py.numpy.load("test_2.npy");
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>> a = double(a_np);
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>> whos
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Name Size Bytes Class Attributes
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a 100x10 8000 double
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a_np 1x1 8 py.numpy.ndarray
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```
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## References
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* [Access Python Modules from MATLAB - Getting Started](https://de.mathworks.com/help/matlab/matlab_external/create-object-from-python-class.html)
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* [Use Python str Variables in MATLAB](https://de.mathworks.com/help/matlab/matlab_external/pythonstrvariables.html)
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* [Use Python list Variables in MATLAB](https://de.mathworks.com/help/matlab/matlab_external/pythonlistvariables.html)
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* [Use Python tuple Variables in MATLAB](https://de.mathworks.com/help/matlab/matlab_external/pythontuplevariables.html)
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* [Use Python dict Variables in MATLAB](https://de.mathworks.com/help/matlab/matlab_external/python-dict-variables.html)
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* [Call User-Defined Python Module](https://de.mathworks.com/help/matlab/matlab_external/call-user-defined-custom-module.html)
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