The Gotchas: For Loops

# WEBINAR: For Loops

# We use loops to repeat actions
# a WHILE loop... is an IF that repeats as long as the loop condition remains True
#
# FOR LOOPS are used for repeating actions for every element in a container (list, dict, tuple, str, range, etc)

# Basic syntax of a for loop
# for ___ in _someContainer_:

# For Loop variables (the word after the for keyword) are SPECIAL VARIABLES that come along with this loop

# # LIST
myList = ["Agent Scully", "Agent Mulder", "Walter Skinner", "CSM", "Mr. X"]
# for item in myList:
#     print(item)

# # TUPLE
# myTuple = ("Gilligan", "Castaway002", "red", "crew")
# for item in myTuple:
#     print(item)
#
# # STRING
# myStr = "It was the best of times."
# for char in myStr:
#     print(char)

# LOOP A NUMBER OF TIMES
# RANGE OBJECT... range()
# range(start=0, stop, step=1)
# range(0, 5, 1) --> range(5) --> [0, 1, 2, 3, 4] # not a list, but we'll pretend it looks like this

# for n in range(5):
#     print(n)

# Looping over an indexed container, and I need to know the INDEX
# 2 choices... range() of len(), enumerate()
# RANGE OF LEN
# for i in range(len(myList)):
#     # print(i)
#     # print(myList[i])
#    print(f"{i}: {myList[i]}")
#
# # ENUMERATE
# for i, item in enumerate(myList):
#     print(f"{i}--> {item}")

# DICT

bestOfXF = {
    "1x00": "Pilot",
    "2x10": "Red Museum",
    "2x14": "Die Hand Die Verletzt",
    "2x20": "Humbug",
    "3x04": "Clyde Bruckman's Final Repose",
    "3x12": "War of the Coprophages",
    "3x20": "Jose Chung's From Outer Space",
    "4x05": "The Field Where I Died",
    "5x05": "The Post Modern Prometheus",
    "5x17": "All Souls"
}


# for ___ in thisDict:
# for key in bestOfXF:
#     # print(key)
#     # print(bestOfXF[key])
#     # "Check out Episode ___ or '---'."
#     print(f"Check out Episode {key} or '{bestOfXF[key]}'.")

# EXTRA... this is a general pattern you'll use a lot with all types of containers
# FILL THE BASKET / FILTER
# agentList = [] # start a new container
# for item in myList:
#     # filter with an if
#     if "Agent" in item:
#         agentList.append(item)
# print(agentList)

# STUDENT QUESTIONS
# ... we're leaving the general topic of for loops now. Lots of questions on dictionaries today.

# If I know I want a certain key and its value, I don't need to loop:
print(bestOfXF["3x12"])

# You can loop to find a key, and then its value, but you don't have to.
# But you can get the value for a key directly if you know its there, no loop needed.
for k in bestOfXF:
    if k == "3x12":
        print(k, bestOfXF[k])

if k in bestOfXF: # check to see if key is there
    print(bestOfXF["3x12"])

# looking for a value, grabbing key when you find it:
for key in bestOfXF:
    # check values
    if bestOfXF[key] == "Jose Chung's From Outer Space":
        # found it!
        rememberThis = key
print(f"I found the episode code! It's {rememberThis}")
# in the above situation, checking based on value instead of key, you DO have to loop.
# Remember values are not necessarily unique though. They can repeat for many keys. Keys on the other hand, can only occur once.