JS - itertools code + readme

Author: hobojoe1848

days/19-21-itertools/README.md

@@ -1,21 +1,35 @@
 # Days 19-21: Itertools
 
+Iteration is something you absolutely have to grasp in order to master Python. 
 
+Itertools helps make iteration simpler and is incredibly powerful which is why you'll be learning it for the next 3 days! 
 
 
-## Day N: Watch videos and <x>!
+## Day N: Watch videos and Play in the Shell!
 
+For your first day, watch all of the videos up until the traffic lights app.
 
+After watching the first 4 videos pop into your Python shell and start playing around with `cycle()`, `product()`, `combinations()` and `permutations()`.
 
 
-## Day N+1: <x>
+## Day N+1: Create a Traffic Lights script
 
+Yep that's right! For your second day, use itertools to create a script that simulates traffic lights!
 
+If you get absolutely stuck, watch the *Traffic Lights* video to see how we did it.
 
 
 ## Day N+2: Your Turn!
 
+For your last day, I'm going to suggest you head to our [codechalleng.es](https://codechalleng.es) platform and take a few of the itertools themed Bites.
 
+The following 3 links will get you free access to the Bites:
+
+[Bite 64](https://codechalleng.es/bites/promo/itertools-fun1)
+[Bite 17](https://codechalleng.es/bites/promo/itertools-fun2)
+[Bite 65](https://codechalleng.es/bites/promo/itertools-fun3)
+
+You don't need to do them in any particular order, they're just there for you to learn something!
 
 
 ### Time to share what you've accomplished!

days/19-21-itertools/code/cycle_demo.py

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+import itertools
+import sys
+import time
+
+symbols = itertools.cycle('-\|/')
+
+while True:
+    sys.stdout.write('\r' + next(symbols))
+    sys.stdout.flush()
+    time.sleep(0.1)

days/19-21-itertools/code/permutations.py

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+from itertools import permutations, combinations
+
+friends = 'mike bob julian'.split()
+# note that we get a generator so using list to consume it
+print(list(combinations(friends, 2)))
+
+# what if order matters?
+print(list(permutations(friends, 2)))

days/19-21-itertools/code/spinner.py

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+import itertools
+import sys
+import time
+
+
+def spinner(seconds):
+    """Show an animated spinner while we sleep."""
+    symbols = itertools.cycle('-\|/')
+    tend = time.time() + seconds
+    while time.time() < tend:
+        # '\r' is carriage return: return cursor to the start of the line.
+        sys.stdout.write('\rPlease wait... ' + next(symbols))  # no newline
+        sys.stdout.flush()
+        time.sleep(0.1)
+    print()
+
+
+if __name__ == "__main__":
+    spinner(3)

days/19-21-itertools/code/traffic_lights.py

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+from time import sleep
+import itertools
+import random
+
+colours = 'Red Green Amber'.split()
+rotation = itertools.cycle(colours)
+
+def rg_timer():
+    return random.randint(3, 7)
+
+def light_rotation(rotation):
+    for colour in rotation:
+        if colour == 'Amber':
+            print('Caution! The light is %s' % colour)
+            sleep(3)
+        elif colour == 'Red':
+            print('STOP! The light is %s' % colour)
+            sleep(rg_timer())
+        else:
+            print('Go! The light is %s' % colour)
+            sleep(rg_timer())
+
+if __name__ == '__main__':
+    light_rotation(rotation)