7. Attach Model and Custom Phi Initialization¶

Detailed description of all parameters and methods of BigARTM Python API classes can be found in Python Interface.

Library supports an ability to access all $\Phi$ -like matrices directly from Python. This is a low-level functionality, so it wasn’t included in the ARTM class, and can be used via low-level master_component interface. User can attach the matrix, e.g. get reference to it in the Python, and can change it’s content between the iterations. The changes will be written in the native C++ memory.

The most evidence case of usage of this feature is a custom initialization of $\Phi$ matrix. The library initalizes it with random numbers by default. But there’re several more complex and useful methods of initialization, that the library doesn’t support yet. And in this case attach_model method can help you.

So let’s attach to the $\Phi$ matrix of our model:

(_, phi_ref) = model.master.attach_model(model=model.model_pwt)

At this moment you can print $\Phi$ matrix to see it’s content:

model.get_phi(model_name=model.model_pwt)

Next code can be used to check whether the attaching was successful:

for model_description in model.info.model:
     print model_description

The output will be similar to the following

name: "nwt"

type: "class artm::core::DensePhiMatrix"

num_topics: 50

num_tokens: 2500

name: "pwt"

type: "class __artm::core::AttachedPhiMatrix__"

num_topics: 50

num_tokens: 2500

You can see, that the type of $\Phi$ matrix has changed from DensePhiMatrix to AttachedPhiMatrix.

Now let’s assume that you have created pwt_new matrix with the same size, filled with custom values. Let’s write these values into our $\Phi$ matrix.

Note

You need to write the values by accessing phi_ref variable, you are not allowed to assing it the whole pwt_new matrix, this operation will lead to an error in future work.

numpy.copyto(phi_ref, new_phi.values)  # CORRECT!

phi_ref = pwt_new  # NO!

After that you can print $\Phi$ matrix again and check the change of it’s values. From this moment you can continue our work.