restruture old ch02 into appendix A

appendix-A/02_installing-python-libraries/python_environment_check.py

@@ -0,0 +1,62 @@
+# Sebastian Raschka, 2023
+
+from os.path import dirname, join, realpath
+from packaging.version import parse as version_parse
+import platform
+import sys
+
+if version_parse(platform.python_version()) < version_parse('3.9'):
+    print('[FAIL] We recommend Python 3.9 or newer but'
+          ' found version %s' % (sys.version))
+else:
+    print('[OK] Your Python version is %s' % (platform.python_version()))
+
+
+def get_packages(pkgs):
+    versions = []
+    for p in pkgs:
+        try:
+            imported = __import__(p)
+            try:
+                versions.append(imported.__version__)
+            except AttributeError:
+                try:
+                    versions.append(imported.version)
+                except AttributeError:
+                    try:
+                        versions.append(imported.version_info)
+                    except AttributeError:
+                        versions.append('0.0')
+        except ImportError:
+            print(f'[FAIL]: {p} is not installed and/or cannot be imported.')
+            versions.append('N/A')
+    return versions
+
+
+def get_requirements_dict():
+    PROJECT_ROOT = dirname(realpath(__file__))
+    REQUIREMENTS_FILE = join(PROJECT_ROOT, "requirements.txt")
+    d = {}
+    with open(REQUIREMENTS_FILE) as f:
+        for line in f:
+            line = line.split(" ")
+            d[line[0]] = line[-1]
+    return d
+
+
+def check_packages(d):
+    versions = get_packages(d.keys())
+
+    for (pkg_name, suggested_ver), actual_ver in zip(d.items(), versions):
+        if actual_ver == 'N/A':
+            continue
+        actual_ver, suggested_ver = version_parse(actual_ver), version_parse(suggested_ver)
+        if actual_ver < suggested_ver:
+            print(f'[FAIL] {pkg_name} {actual_ver}, please upgrade to >= {suggested_ver}')
+        else:
+            print(f'[OK] {pkg_name} {actual_ver}')
+
+
+if __name__ == '__main__':
+    d = get_requirements_dict()
+    check_packages(d)