AC: install core components command (openvinotoolkit#872)

Author: eaidova

tools/accuracy_checker/README.md

@@ -61,11 +61,11 @@ If all prerequisite are installed, then you are ready to install **accuracy chec
 python3 setup.py install
 ```
 
-Accuracy Checker is modular tool and have some task-specific dependencies, all required modules can be found in `requirements.in` file.
-You can install tool without dependencies and manage them by your-self using following command instead of standard installation:
+Accuracy Checker is modular tool and have some task-specific dependencies, all specific required modules can be found in `requirements.in` file.
+You can install only core part of the tool without additional dependencies and manage them by your-self using following command instead of standard installation:
 
 ```bash
-pip install . --no-dependencies
+python setup.py install_core
 ```
 
 #### Usage

tools/accuracy_checker/requirements-core.in

@@ -0,0 +1,3 @@
+# core components
+numpy>=1.11,<1.18
+PyYAML

tools/accuracy_checker/requirements.in

@@ -1,7 +1,3 @@
-# core components
-numpy>=1.11,<1.18
-PyYAML
-
 # progress bar
 tqdm
 

tools/accuracy_checker/setup.py

@@ -17,8 +17,10 @@
 import importlib
 import re
 import sys
+import warnings
 from setuptools import find_packages, setup
 from setuptools.command.test import test as test_command
+from setuptools.command.install import install as install_command
 from pathlib import Path
 
 
@@ -44,6 +46,10 @@ def read(*path):
         return file.read()
 
 
+class CoreInstall(install_command):
+    pass
+
+
 def find_version(*path):
     version_file = read(*path)
     version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]", version_file, re.M)
@@ -56,11 +62,14 @@ def find_version(*path):
 long_description = read("README.md")
 version = find_version("accuracy_checker", "__init__.py")
 
-requirements = [read("requirements.in")]
+requirements = [read('requirements-core.in') + read("requirements.in") if 'install_core' not in sys.argv else '']
 
 try:
     importlib.import_module('cv2')
-except ImportError:
+except ImportError as opencv_import_error:
+    warnings.warn(
+        "Problem with cv2 import: \n{}\n opencv-python will be added to requirements".format(opencv_import_error)
+    )
     requirements.append('opencv-python')
 
 setup(
@@ -78,5 +87,5 @@ def find_version(*path):
     python_requires='>=3.5',
     install_requires=requirements,
     tests_require=[read("requirements-test.in")],
-    cmdclass={'test': PyTest}
+    cmdclass={'test': PyTest, 'install_core': CoreInstall}
 )