Programming Exercises

What you'll learn

In this activity, you will:

• Practice joining DataFrames using pandas
• Work with data from dictionaries and CSV files
• Learn to set indexes and merge data based on common columns
• Apply data manipulation skills to combine related datasets

Overview

:computer: Activity Type: Coding Exercise
⏱️ Total Time: 30-40 minutes
:emoji: Platform: Google Colab

Complete the exercises in this Google Colab notebook: https://colab.research.google.com/drive/1TLgmP8CStA7oQd33V47U1wI_4LJc6ibB?usp=sharing

Getting Started

:warning: Important Setup Steps

1. Make a copy of the Colab file before you start coding
2. Click "File" -> "Save a copy in Drive"
3. Work in YOUR COPY, not the template file
4. Rename your copy to include your name: "Pandas_Joining_YourName"

Question One: Join Height and Weight Data

⏱️ Estimated Time: 15-20 minutes

Your Task

You'll combine height and weight data from two separate dictionaries into a single DataFrame.

Steps to Complete:

1. Create the data structures

   • Start with two nested dictionaries (provided in the notebook)
   • One dictionary contains heights, the other contains weights
   • Both use first names as keys

2. Convert to DataFrames

   • Convert the height dictionary to a DataFrame called df_height
   • Convert the weight dictionary to a DataFrame called df_weight

3. Explore your data

   • Display both DataFrames using print() or just the variable name
   • Check the column names and row structure

4. Set the index

   • Use set_index() to set the "first name" column as the index for both DataFrames
   • This prepares them for joining on matching names

5. Join the DataFrames

   • Use the join() method to combine the DataFrames
   • The result should show both height and weight for each person

:bulb: Helpful Hint Remember that when you set an index, it becomes the "key" that pandas uses to match rows between DataFrames. Make sure both DataFrames have the same index column before joining!

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Question 2: Join Age and Races Data from CSV

⏱️ Estimated Time: 15-20 minutes

Your Task

You'll work with CSV files to practice joining data from external sources.

Steps to Complete:

1. Upload the CSV files

   • Upload age.csv and races.csv to your Colab environment
   • Click the folder icon on the left sidebar
   • Use the upload button to add both files

2. Read the CSV files

   • Use pd.read_csv() to load age.csv into a DataFrame called age
   • Use pd.read_csv() to load races.csv into a DataFrame called races

3. Examine the data

   • Display both DataFrames to understand their structure
   • Confirm that both have a "Name" column
   • Check for any missing values or data issues

4. Prepare for joining

   • Set the "Name" column as the index for the age DataFrame
   • Set the "Name" column as the index for the races DataFrame
   • This ensures pandas can match people by their names

5. Perform the join

   • Use the join() method to combine the DataFrames
   • Your final DataFrame should contain name, age, and race information

:bulb: Common Challenge If you get an error when uploading files, try refreshing the Colab page and uploading again. Make sure the file names match exactly (including capitalization).

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Troubleshooting Guide

Common Issues and Solutions:

"KeyError" when joining:

• Check that both DataFrames have the correct index set
• Verify column names match exactly (case-sensitive)

CSV files won't upload:

• Refresh your Colab notebook
• Check file size (should be small for this exercise)
• Try dragging and dropping instead of clicking upload

Join results in missing data:

• Some names might not match between datasets
• Check for extra spaces or different spellings
• Use how='outer' parameter in join to see all data

Before You Submit

:white_check_mark: Checklist:

• Both exercises completed in your copy of the notebook
• All code cells run without errors
• Output displayed for each step
• File saved with your name in the title

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Submission

:information_source: Submit Your Work :memo: Ready to submit? Make sure you've:

1. Completed both exercises
2. Saved your Colab notebook
3. Reviewed your code and outputs

:link: Submit your exercise here

:alarm_clock: Submission deadline: Check with your instructor