Resolves issue #31

main.py

@@ -35,7 +35,29 @@ def get_pip_command():
 def install_dependencies():
 
     pip_command = get_pip_command()
-    subprocess.check_call([pip_command, 'install', '-r', 'requirements.txt', '--user'])
+    
+    with open('requirements.txt', 'r') as req_file:
+        
+        requirements = req_file.read().splitlines()
+
+    try:
+        
+        with open('installedrequirements.txt', 'r') as installed_file:
+            installed_requirements = installed_file.read().splitlines()
+    
+    except FileNotFoundError:
+        
+        installed_requirements = []
+
+    dependencies_to_install = [req for req in requirements if req not in installed_requirements]
+
+    if dependencies_to_install:
+
+        subprocess.check_call([pip_command, 'install'] + dependencies_to_install + ['--user'])
+
+        with open('installedrequirements.txt', 'a') as installed_file:
+            for dependency in dependencies_to_install:
+                installed_file.write(dependency + '\n')
 
 def signal_handler(sig, frame):
     print('SIGINT/SIGTERM aknowledged. Stopping script gracefully, please wait...')