webinar-for-loops-2021-02-05

# 2022 Feb5
# WEBINAR: For Loops
# We use loops to repeat actions

# a WHILE loop... btw.. is basically an IF statement
# that repeats as long as its condition is true

# FOR LOOPS are used for repeating actions for every element
# in a container like a list, string, tuple, etc...

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

myTuple = ("Gilligan", "Castaway002", "red", "crew")
for item in myTuple:
    print(item)

myString = "Just sit right back and you'll hear a tale."
for char in myString:
    print(char, end="-") # whenever you override end parameter of print()...
# print("the next thing")
print() # get a clean line... see Ch 2.9
print("the next thing")

# looping over dictionaries
scoobiesDCT = {
    "Scooby": "a blue collar",
    "Shaggy": "green",
    "Velma": "orange",
    "Daphne": "purple",
    "Fred": "an ascot"
}
for key in scoobiesDCT: # for loop var with dicts is the KEY
    print(f"{key} wears {scoobiesDCT[key]}.")
    # f string... same as....
    # print("{} wears {}.".format(key, scoobiesDCT[key]))

# myDictionary[someKey] --> retrieve the value for that key
# myDictionary[someKey] = value

# range()
for n in range(0, 5):
    print(f"{n} hey")

# using range() to look at index of list items
myList.append("Krycek")
for i in range(0, len(myList)):
    print("{}: {}".format(i, myList[i]))

# # could do same with enumerate()
# for i, item in enumerate(myTuple):
#     print("{}: {}".format(i, myTuple[i]))

numList = [0, 1, 2, 3, 4] # 0 -> 1 -> 2 -> 3 -> 4
for i in range(0, len(numList)):
    if i < len(numList) - 1:
        print("{} ->".format(i), end=" ") # most of time, but not on the last
    else:
        print(i)
# print() # print on else above makes this unnecessary


# We use for loops when looping over line by line data from files...

# I have a CSV file named "mock_data.csv"
with open("mock_data.csv", "r") as f:
    # read() --> returns whole file as one big str
    # readlines() --> returns you a line by line list of strings

    # print(f.readlines()) # you'll see all those \n returns in each string
    for line in f.readlines():
        # print(type(line))
        # print(line)
        # myInputVar = input().rstrip()
        line = line.rstrip()
        # print(line.split(","))
        lineList = line.split(",")
        # print(lineList[1]) # first names
        print("{}'s email is {}.".format(lineList[1], lineList[3]))