Dictionaries, Files and Error Handling

student = {
    "name": "Aisha",
    "year": 11,
    "grades": [8, 9, 7],
    "active": True
}

print(student["name"])          # Aisha
student["year"] = 12            # change a value
student["house"] = "Blue"       # add a new pair
del student["active"]           # remove a pair

print(student.get("email"))                 # None, no crash
print(student.get("email", "not given"))    # a default value
print("name" in student)                    # True

for key in student:
    print(key, "=", student[key])

for key, value in student.items():
    print(f"{key}: {value}")

print(list(student.keys()))
print(list(student.values()))

students = [
    {"name": "Aisha", "mark": 92},
    {"name": "Ben", "mark": 68},
    {"name": "Chloe", "mark": 77},
]

for s in students:
    print(f"{s['name']:<8} {s['mark']}")

best = max(students, key=lambda s: s["mark"])
print("Top:", best["name"])

average = sum(s["mark"] for s in students) / len(students)
print(f"Average: {average:.1f}")

point = (3, 7)              # a tuple, cannot be changed
x, y = point                # unpacking

unique = {1, 2, 2, 3, 3}    # a set, duplicates removed
print(unique)               # {1, 2, 3}

# Write, which ERASES the file first
with open("scores.txt", "w") as file:
    file.write("Aisha,92\n")
    file.write("Ben,68\n")

# Append, which adds to the end
with open("scores.txt", "a") as file:
    file.write("Chloe,77\n")

# Read line by line
with open("scores.txt", "r") as file:
    for line in file:
        name, mark = line.strip().split(",")
        print(f"{name} scored {mark}")

# Read the whole file
with open("scores.txt", "r") as file:
    contents = file.read()

# Read into a list of lines
with open("scores.txt", "r") as file:
    lines = file.readlines()

import csv

with open("students.csv", "w", newline="") as file:
    writer = csv.writer(file)
    writer.writerow(["Name", "Mark"])
    writer.writerow(["Aisha", 92])

with open("students.csv", "r") as file:
    reader = csv.reader(file)
    next(reader)                     # skip the header row
    for row in reader:
        print(row[0], row[1])

import json

data = {"players": ["Aisha", "Ben"], "high_score": 4200}

with open("save.json", "w") as file:
    json.dump(data, file)

with open("save.json", "r") as file:
    loaded = json.load(file)

print(loaded["high_score"])

try:
    age = int(input("Enter your age: "))
    print(f"Next year you will be {age + 1}")
except ValueError:
    print("That was not a whole number.")

try:
    with open("data.txt", "r") as file:
        numbers = [int(line) for line in file]
    print(sum(numbers) / len(numbers))

except FileNotFoundError:
    print("The file does not exist yet.")
except ValueError:
    print("The file contains something that is not a number.")
except ZeroDivisionError:
    print("The file is empty.")
else:
    print("Everything worked.")
finally:
    print("Finished.")

def get_int(prompt, low, high):
    while True:
        try:
            value = int(input(prompt))
            if low <= value <= high:
                return value
            print(f"Please enter a number between {low} and {high}.")
        except ValueError:
            print("That is not a whole number.")