webinar-for-loops-2023-07-08

# 2023 July 8
# 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, str, tuples, sets, dictionary, range objects)

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

# list
# myList = ["Agent Scully", "Agent Mulder", "Walter Skinner", "CSM", "Mr. X"]
# for item in myList:
#     print(item)
#
# # tuples
# myTuple = ("Gilligan", "Castaway002", "red", "crew")
# for item in myTuple:
#     print(item)
#
# # strings
# myString = "It was the best of times."
# for char in myString:
#     print(char)
#
# # dictionaries
# # { key: value, key:value}
# # myDict[key] # retrieve the value for that key
# # myDict[key] = value # assign value to key
# bestOfXF = {
#     "1x00": "Pilot",
#     "2x10": "Red Museum",
#     "2x14": "Die Hand Die Verletzt",
#     "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 key in bestOfXF:
#     # "Check out Episode ___ or '___'"
#     print(f"Check out Episode {key} or '{bestOfXF[key]}'")

# to just to do something X number of times... range objects
for num in range(7): # range(start, stop, step)... range(0, 7, 1) --> [0, 1, 2, 3, 4, 5, 6]
    print(num)

myList = ["Agent Scully", "Agent Mulder", "Walter Skinner", "CSM", "Mr. X"]
# if I need to know the index, then
# for item/value in myList:
for i in range(len(myList)):
    print(f"{i}: {myList[i]}")

# could also use ENUMERATE
for i, item in enumerate(myList):
    print("{} - {}".format(i, item))



# STUDENT QUESTIONS
# making dictionaries from lists... well that depends on what's in the list or lists you're starting with...
# ... and what you want in the dictionary you're making

# 1:1 Correspondence between lists... entries in one are keys and entries in other are their values
myList = ["Agent Scully", "Agent Mulder", "Walter Skinner", "CSM", "Mr. X"]
pets = ["Queequeg", "goldfish", "dog", "the human race", "cat"]


petDict = {}
for i in range(len(myList)):
    # myDict[key] = value
    petDict[myList[i]] = pets[i]
print(petDict) # {'Agent Scully': 'Queequeg', 'Agent Mulder': 'goldfish', 'Walter Skinner': 'dog', 'CSM': 'the human race', 'Mr. X': 'cat'}


# Alternating key, value data from one list
anotherList = ["Agent Scully", "red ", " Agent Mulder", " gray", "Walter Skinner ", "  white", "CSM", "\nblue", "Mr. X", "purple"]
anotherDict = {}
for i in range(0, len(anotherList), 2): # use the step
    # myDict[key] = value
    anotherDict[anotherList[i].strip()] = anotherList[i+1].strip()
print(anotherDict) # {'Agent Scully': 'red', 'Agent Mulder': 'gray', 'Walter Skinner': 'white', 'CSM': 'blue', 'Mr. X': 'purple'}


# Alternating key, value data from one list with potential repeat keys
anotherList = ["Agent Scully", "red", " Agent Mulder", "gray", "Walter Skinner", "white", "CSM", "blue", "Mr. X", "purple", "CSM", "pink"]
checkDict = {} # we'll check to see if the key is already there
for i in range(0, len(anotherList), 2):
    if anotherList[i] in checkDict:
        # if it's there, add to it in some way...
        # value... "item1; item2"
        checkDict[anotherList[i]] += "; " + anotherList[i+1]
    else:
        checkDict[anotherList[i]] = anotherList[i + 1] # add if it's not there
# print(checkDict) # {'Agent Scully': 'red', ' Agent Mulder': 'gray', 'Walter Skinner': 'white', 'CSM': 'blue; pink', 'Mr. X': 'purple'}



# Student question Lab 14.10
# one approach...

# TODO: Declare any necessary variables here.
filename = input()
lastNames = []
firstNames = []
mid1 = []
mid2 = []
finals = []

# TODO: Read a file name from the user and read the tsv file here.
import csv

with open(filename, "r") as f:
    contents = list(csv.reader(f, delimiter="\t"))
# print(contents) # sometimes it helps to just print something and look at it
for line in contents:
    lastNames.append(line[0])
    firstNames.append(line[1])
    mid1.append(int(line[2]))
    mid2.append(int(line[3]))
    finals.append(int(line[4]))

# TODO: Compute student grades and exam averages, then output results to a text file here.
with open("report.txt", "w") as f:
    for i in range(len(lastNames)): # we're using corresponding indices again
        gradesList = [mid1[i], mid2[i], finals[i]]
        avg = sum(gradesList) / len(gradesList)
        if avg >= 90:
            ltr = "A"
        elif avg >= 80:
            ltr = "B"
        elif avg >= 70:
            ltr = "C"
        elif avg >= 60:
            ltr = "D"
        else:
            ltr = "F"
        # that contents var based on the original file is still around! Let's use it...
        f.write("\t".join(contents[i]) + f"\t{ltr}\n") # part of the loop
    # NOT part of the loop!
    f.write(f"\nAverages: midterm1 {sum(mid1) / len(mid1):.2f}, midterm2 {sum(mid2) / len(mid2):.2f}, final {sum(finals) / len(finals):.2f}\n")