# Before we begin, let us silence any warning messages.
import warnings
warnings.filterwarnings("ignore")

# Let us check Python's version. Notebooks often show the version being used.
import sys
print("Python version:", sys.version)

# Let us try a simple print statement to see how output works.
print("Hello, world!")

# Let us assign our first variable.
name = "Alice"
print("Nice to meet you,", name)

# Variables can be numbers too.
x = 3
y = 7
sum_xy = x + y
print("The sum is:", sum_xy)

# Let us try inputting your name yourself.
your_name = input("What is your name? ")
print("Hello,", your_name)

# Download and look at the airline passengers dataset.
import pandas as pd
url = "https://raw.githubusercontent.com/jbrownlee/Datasets/master/airline-passengers.csv"
df = pd.read_csv(url)
print("Shape of data:", df.shape)
df.head()

# Let us make a quick plot of the data.
import matplotlib.pyplot as plt
plt.figure(figsize=(10,4))
plt.plot(df['Month'], df['Passengers'])
plt.xlabel('Month')
plt.ylabel('Number of Passengers')
plt.title('Airline Passengers Over Time')
plt.xticks(rotation=45)
plt.tight_layout()
plt.show()

# Make a dataframe from scratch.
sample_data = {
    "Name": ["Ava", "Ben", "Chloe"],
    "Score": [88, 92, 75]
}
df2 = pd.DataFrame(sample_data)
print("Sample table:")
df2

# Select just one column: the names.
names_column = df2["Name"]
print("Names:", list(names_column))

# Add a new column to our small table.
df2["Passed"] = df2["Score"] >= 80
print(df2)

# Remove a column from the table.
df2 = df2.drop("Passed", axis=1)
print(df2)

# Basic error: try to access a column that does not exist.
try:
    print(df2["Grade"])
except KeyError as e:
    print("Oops! Column not found:", e)
    

# Sort the table by score from highest to lowest.
df_sorted = df2.sort_values(by="Score", ascending=False)
print(df_sorted)

# Filter the table: show only scores above 80.
passed_students = df2[df2["Score"] > 80]
print(passed_students)

# Loop through the names in the table and greet each person.
for n in df2["Name"]:
    print("Hello,", n)
    

# Challenge: Add a new row to the table using user input.
new_name = input("Enter a new student's name: ")
new_score = int(input("Enter the new score: "))
df2 = pd.concat([df2, pd.DataFrame({"Name": [new_name], "Score": [new_score]})], ignore_index=True)
print(df2)