Write OP Implementation in Python - 2.0 English

An add OP is used as an example in this section.

1. Create a Python package and a module file.

   % mkdir -p /tmp/demo_add_op/
   % cd /tmp/demo_add_op/
   % mkdir vart_op_imp/
   % touch vart_op_imp/__init__.py
   % touch vart_op_imp/add.py

2. Update add.py as below.

   import numpy as np
   
   
   class add:
       def __init__(self, op):
           pass
   
       def calculate(self, output, input):
           np_output = np.array(output, copy=False)
           L = len(input)
           if L == 0:
               return
           np_input_0 = np.array(input[0], copy=False)
           np.copyto(np_output, np_input_0)
           for i in range(1, L):
               np_output = np.add(np_output,
                                  np.array(input[i], copy=False),
                                  out=np_output)

   You can also use the following simplified version.

   import numpy as np
   
   
   class add:
       def __init__(self, op):
           pass
   
       def calculate(self, output, input):
           np_output = np.array(output, copy=False)
           L = len(input)
           assert L == 2
           np_input_0 = np.array(input[0], copy=False)
           np_input_1 = np.array(input[1], copy=False)
           np_output = np.add(np_input_0, np_input_1, out=np_output)

3. Install the op as below.

   % mkdir -p lib
   % ln -sf ~/.local/Ubuntu.18.04.x86_64.Debug/lib/libvart_op_imp_python-cpu-op.so lib/libvart_op_imp_add.so
   % ls -l lib
   % mkdir -p dump
   % env LD_LIBRARY_PATH=$HOME/.local/Ubuntu.18.04.x86_64.Debug/lib:$PWD/lib $HOME/.local/Ubuntu.18.04.x86_64.Debug/share/vitis_ai_library/test/cpu_task/test_op_imp --graph /tmp/add.xmodel --op "add_op"

For Edge, you can execute the following command to install and test the op.

# ls -sf /usr/lib/libvart_op_imp_python-cpu-op.so /usr/lib/libvart_op_imp_add.so
# cp -r vart_op_imp /usr/lib.python3.8/site-packages
# xdputil run_op add.xmodel add_op -r ref -d dump

Similar to the C++ interface, the Python module must have a class whose name is the same as the xir::Op's type. It is add in the example. The class must have a constructor with a single argument op in addition to self. It is an XIR::Op. Refer to the XIR Python API for more detail. Similarly, the class add must have a member function calculate, in addition to self argument, the first argument must be named output, and following argument names must comply with the XIR::OpDef associated with the XIR::Op, refer to XIR API for more detail.