Excel to Pandas (Zillow): Practice Exercises

Now that you’ve worked through the Excel_to_Pandas_Zillow_Basic.ipynb and Excel_to_Pandas_Zillow_Advanced.ipynb tutorials, you’re ready to apply those skills independently. Use the Zillow data below to complete each exercise and reinforce what you’ve learned.

Professor: Khai Lu
Developer: Rinrada Maneenop
Estimated Time: ~20 minutes

Contents:

Setup (imports and data loading)
Exercise 1: State-Level Filtering and Aggregation
Exercise 2: Pivot Table by Market Tier and State
Exercise 3: Year-Over-Year Growth Chart
Exercise 4: Buy vs. Rent Analysis
Conclusion

Please run the cell below to import all the necessary libraries so your notebook can run without issues!
NOTE: DO NOT edit the cell below, please only run it.

# Import necessary libraries
import sys
from pathlib import Path
import subprocess
import importlib.util

# Install required packages in this kernel only when missing
required_packages = ["pandas", "numpy", "matplotlib", "seaborn", "ipywidgets"]
missing_packages = [pkg for pkg in required_packages if importlib.util.find_spec(pkg) is None]
if missing_packages:
    subprocess.run([sys.executable, "-m", "pip", "install", "-q", *missing_packages], check=False)

# Local module interact.py lives next to this notebook — add it to path when cwd differs
# (e.g. JupyterHub/cloud kernels often start in /tmp or home, not this folder)
for _p in (
    Path.cwd(),
    Path.cwd() / "excel_to_pandas_zillow",
    Path.cwd() / "cis26" / "excel_to_pandas_zillow",
):
    if (_p / "interact.py").exists():
        sys.path.insert(0, str(_p.resolve()))
        break

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
from IPython.display import display, HTML, Markdown
from interact import (
    explore_data_widget,
    filter_markets_widget,
    pivot_table_widget,
    metro_trends_widget,
)
import warnings
warnings.filterwarnings('ignore')

# Set plot style
plt.style.use('seaborn-v0_8-darkgrid')
sns.set_palette("husl")

print("✅ All libraries imported successfully!")
print("\n📌 Note: This notebook uses interactive widgets (ipywidgets)")
print("   You'll see dropdowns and sliders throughout — just run each cell and use the controls!")

Please run the cell below to import necessary variables we have defined earlier in the Excel_to_Pandas_Zillow_Basic.ipynb tutorial.

# Load required exercise variables from a reusable helper
from exercise_setup import load_exercise_data

_data = load_exercise_data(verbose=True)

home_values_wide = _data["home_values_wide"]
rent_values_wide = _data["rent_values_wide"]
home_values = _data["home_values"]
rent_values = _data["rent_values"]
home_values_latest = _data["home_values_latest"]
latest_home_values_copy = _data["latest_home_values_copy"]
housing_combined = _data["housing_combined"]

Exercise 1: State-Level Filtering and Aggregation¶

Find all metro areas in Texas (TX) where the current median home value is above the national median. Display the results sorted by home value (descending).

Hint: Calculate the national median first, then use boolean indexing with two conditions.

Guidelines

Compute the national median using home_values_latest['HomeValue'].median().
Filter home_values_latest to rows where StateName == 'TX' and HomeValue is greater than the national median.
Sort the filtered result by HomeValue in descending order.
Display a table with RegionName and HomeValue.

#Your code here

#Step 1: Compute the national median home value
national_median = home_values_latest[ ... ]
print(f"National median home value: ${national_median:,.0f}")

#Step 2: Filter to Texas metros with HomeValue above the national median
tx_above_national = home_values_latest[ ... ]

#Step 3: Sort by HomeValue (descending) and display RegionName and HomeValue
tx_above_national = tx_above_national.sort_values( ... )
display(tx_above_national[[ ... ]])

# Solution: Exercise 1

national_median = home_values_latest['HomeValue'].median()
print(f'National median home value: ${national_median:,.0f}')

tx_above_national = home_values_latest[
    (home_values_latest['StateName'] == 'TX') &
    (home_values_latest['HomeValue'] > national_median)
].sort_values('HomeValue', ascending=False)

print(f"\nTexas metros above national median: {len(tx_above_national)}")
display(tx_above_national[['RegionName', 'HomeValue']])

Exercise 2: Pivot Table — Average Home Value by Market Tier and State¶

Create a pivot table showing the average home value for each Market Tier broken down by the top 8 states (by metro count). Add row/column margins.

Hint: Use latest_home_values_copy which already has the MarketTier column.

Guidelines

Count metros per state and select the top 8 states.
Filter latest_home_values_copy to rows where StateName is in that top-8 list.
Use pivot_table with:
- values='HomeValue'
- index='StateName'
- columns='MarketTier'
- aggfunc='mean'
- margins=True for totals.
Optionally round the result for nicer display.

# Your code here

# Step 1: Identify the top 8 states by metro count
top8_states = ...

# Step 2: Filter latest_home_values_copy to only those top-8 states
filtered = ...

# Step 3: Build a pivot table of average HomeValue by StateName and MarketTier
pivot_ex2 = filtered.pivot_table(
    values=...,  # column to aggregate
    index=...,   # rows
    columns=..., # columns
    aggfunc=..., # aggregation function
    fill_value=0,
    margins=True,
)

# Step 4: Optionally round and display the result
pivot_ex2 = pivot_ex2.round(0)
display(pivot_ex2)

# Solution: Exercise 2

top8_states = latest_home_values_copy['StateName'].value_counts().head(8).index

pivot_ex2 = latest_home_values_copy[latest_home_values_copy['StateName'].isin(top8_states)].pivot_table(
    values='HomeValue',
    index='StateName',
    columns='MarketTier',
    aggfunc='mean',
    fill_value=0,
    margins=True
).round(0)

print('Average home value by state and market tier:')
display(pivot_ex2)

Exercise 3: Year-Over-Year Growth Chart¶

Plot the annual median U.S. home value as a line chart. Then add a second line showing the year-over-year percent change.

Hint: Use home_values.groupby('Year') and .pct_change().

Guidelines

Group home_values by Year and compute the median HomeValue for each year.
Use .pct_change() on that annual series to compute YoY percent change.
Create a figure with two subplots side by side using plt.subplots(1, 2, ...).
Plot the annual median values on the first subplot.
Plot the YoY percent change on the second subplot (add a horizontal 0% line for reference).
Add titles, axis labels, and grid lines for readability.

# Your code here

# Step 1: Aggregate to annual median home values
annual_median = ...

# Step 2: Compute year-over-year percent change
annual_growth = ...

# Step 3: Create a figure with two subplots side by side
fig, (ax1, ax2) = plt.subplots(...)

# Step 4: Plot annual_median on the first axis
annual_median.plot(ax=ax1, ...)
ax1.set_title(...)
ax1.set_ylabel(...)

# Step 5: Plot annual_growth on the second axis
annual_growth.plot(ax=ax2, ...)
ax2.axhline(y=0, ...)
ax2.set_title(...)
ax2.set_ylabel(...)

# Step 6: Format the layout
plt.tight_layout()
plt.show()


# Solution: Exercise 3

annual_median = home_values.groupby('Year')['HomeValue'].median()
annual_growth = annual_median.pct_change() * 100

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(14, 5))

annual_median.plot(ax=ax1, marker='o', linewidth=2, color='steelblue')
ax1.set_title('Annual Median Home Value (U.S., All Metros)', fontweight='bold')
ax1.set_ylabel('Home Value ($)')
ax1.grid(True, alpha=0.3)

annual_growth.plot(ax=ax2, marker='o', linewidth=2, color='green', label='YoY growth')
ax2.axhline(y=0, color='red', linestyle='--', alpha=0.5, label='Zero growth')
ax2.set_title('Year-Over-Year Growth Rate (U.S., All Metros)', fontweight='bold')
ax2.set_ylabel('Growth Rate (%)')
ax2.legend()
ax2.grid(True, alpha=0.3)

plt.tight_layout()
plt.show()

Exercise 4: Buy vs. Rent Analysis¶

Using housing_combined, classify metros into ‘Lean Buy’, ‘Neutral’, or ‘Lean Rent’ based on their Price-to-Rent ratio (thresholds: < 15 = Buy, > 20 = Rent). Then create a bar chart showing the count of metros in each category, broken down by state (top 6 states by metro count).

Hint: housing_combined already has Buy_vs_Rent and Price_to_Rent columns.

Guidelines

Identify the top 6 states by metro count in housing_combined.
Filter to those states only.
Group by StateName and Buy_vs_Rent, and use .size() to count metros in each combination.
Use .unstack() so the buy/rent categories become columns.
Plot the resulting table as a grouped bar chart with a clear title, axis labels, and legend.

# Your code here

# Step 1: Find the top 6 states by metro count
top6 = ...

# Step 2: Filter housing_combined to those states
ex4_data = ...

# Step 3: Group by StateName and Buy_vs_Rent and count metros
tier_counts = (
    ex4_data.groupby([ ... ])
    .size()
    .unstack(fill_value=0)
)

# Step 4: Plot the grouped bar chart
plt.figure(...)
tier_counts.plot(kind='bar', ...)
plt.title(...)
plt.xlabel(...)
plt.ylabel(...)
plt.xticks(...)
plt.legend(...)
plt.grid(...)
plt.tight_layout()
plt.show()


# Solution: Exercise 4

top6 = housing_combined['StateName'].value_counts().head(6).index
ex4_data = housing_combined[housing_combined['StateName'].isin(top6)]

tier_counts = (
    ex4_data.groupby(['StateName', 'Buy_vs_Rent'])
    .size()
    .unstack(fill_value=0)
)

plt.figure(figsize=(12, 6))
tier_counts.plot(kind='bar', width=0.8)
plt.title('Buy vs. Rent Signal by State', fontsize=14, fontweight='bold')
plt.xlabel('State')
plt.ylabel('Number of Metros')
plt.xticks(rotation=0)
plt.legend(title='Signal')
plt.grid(axis='y', alpha=0.3)
plt.tight_layout()
plt.show()

Conclusion¶

Congratulations! You’ve translated your Excel skills into Pandas using real Zillow housing market data. Here’s a summary of what you covered:

Key Takeaways:¶

Wide → Long format: pd.melt() is Excel’s “Unpivot” — essential for time series data like home_values
VLOOKUP → merge(): Join datasets with flexible left/inner/outer options
FILTER → Boolean Indexing: Filter rows programmatically with &, |, .isin()
SUMIF/COUNTIF → groupby(): Aggregate across all groups in one line
IF Statements → np.where() / apply(): Create conditional columns at scale
Pivot Tables → pivot_table(): Summarize data with row/column/value dimensions
Charts → matplotlib/seaborn: Reproducible, annotatable, publication-quality plots

Why Pandas > Excel for This Kind of Data:¶

✅ Scalability: The home_values dataset has 300+ metros × 280+ months = 80,000+ data points — trivial for pandas, painful in Excel

✅ Reproducibility: Every transformation is documented in code

✅ Automation: Re-run this notebook every month as new data is released with zero manual effort

✅ Live Data: Load directly from a URL — no manual downloading required

Resources:¶

Quick Reference Cheat Sheet¶

Excel Function	Pandas Equivalent	Zillow Example
File → Open CSV	`pd.read_csv(url)`	`pd.read_csv(home_values_URL)`
Data → Unpivot	`pd.melt()`	Wide home_values → long format
VLOOKUP	`df.merge()`	Join home_values + rent_values by RegionName
VLOOKUP (1 col)	`series.map(dict)`	Map RegionName → home value
AutoFilter	Boolean indexing	`df[df['StateName'] == 'CA']`
FILTER (multi-value)	`.isin()`	`df[df['State'].isin(['CA','NY'])]`
SUMIF	`groupby().sum()`	Total value by state
AVERAGEIF	`groupby().mean()`	Avg home value by tier
COUNTIF	`value_counts()`	Count of metros per state
IF	`np.where()`	Classify Affordable vs Expensive
Nested IFS	`np.select()`	Multi-tier market classification
IF (complex)	`.apply(func)`	Custom categorization logic
=(B-A)/A	`.pct_change()`	Year-over-year home value growth
PivotTable	`pivot_table()`	Value by state × tier
Insert → Chart	`df.plot()`	Time series, bar charts
AVERAGE	`.mean()`	Mean home value nationally
MAX/MIN	`.max()` / `.min()`	Most/least expensive metro

Congratulations on completing From Excel to Pandas: Housing Market Edition! 🎉

You’re now equipped to work with large, real-world datasets — the same data used by housing economists, mortgage analysts, and real estate investors. Keep practicing!

Happy coding! 🐍📊