What is Pandas - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the Purpose of Pandas

What is the main purpose of the Pandas library in data science?

A To build machine learning models

B To create interactive web pages

C To manipulate and analyze data easily

D To design computer graphics

💡 Hint

Think about what you do with tables of data in Python.

Pandas is mainly used to handle and analyze data in tables, making data science tasks easier.

❓ Predict Output

intermediate

Pandas DataFrame Creation Output

What will be the output of this code?

Pandas

import pandas as pd

df = pd.DataFrame({'A': [1, 2], 'B': [3, 4]})
print(df)

A

   A  B
0  1  3
1  2  4

B Error: DataFrame not defined

C {'A': [1, 2], 'B': [3, 4]}

D [[1, 3], [2, 4]]

💡 Hint

Look at how DataFrame prints tabular data.

The DataFrame shows columns A and B with their values in rows indexed 0 and 1.

❓ data_output

advanced

Selecting Data from a DataFrame

Given the DataFrame below, what is the output of df['B'][1]?

Pandas

import pandas as pd

df = pd.DataFrame({'A': [10, 20, 30], 'B': [100, 200, 300]})

A 100

B KeyError

C 30

D 200

💡 Hint

Remember that df['B'] selects column B, then [1] selects the second row.

Column B has values [100, 200, 300]. Index 1 is the second value, 200.

❓ visualization

advanced

Plotting with Pandas

What type of plot will this code produce?

Pandas

import pandas as pd
import matplotlib.pyplot as plt

df = pd.DataFrame({'x': [1, 2, 3], 'y': [4, 5, 6]})
df.plot(x='x', y='y', kind='bar')
plt.show()

A A bar chart showing y values for each x

B A line chart connecting points (x, y)

C A scatter plot of x vs y

D A pie chart of y values

💡 Hint

The kind='bar' argument controls the plot type.

The code creates a bar chart with x on the horizontal axis and y as bar heights.

🔧 Debug

expert

Error Identification in Pandas Code

What error will this code raise?

Pandas

import pandas as pd

df = pd.DataFrame({'A': [1, 2], 'B': [3, 4]})
print(df['C'])

A TypeError

B KeyError

C IndexError

D No error, prints empty column

💡 Hint

Check if column 'C' exists in the DataFrame.

Accessing a non-existent column 'C' raises a KeyError in Pandas.

Practice

1. What is pandas mainly used for in Python?

easy

A. Writing system drivers

B. Creating 3D graphics

C. Building websites

D. Working with tables of data easily

Solution

1. Step 1: Understand pandas purpose

   Pandas is a Python library designed to handle and analyze data in tables.

2. Step 2: Match purpose with options

   Only Working with tables of data easily describes working with tables of data, which matches pandas' main use.

3. Final Answer:

   Working with tables of data easily -> Option D

4. Quick Check:

   pandas = tables of data [OK]

Hint: Remember pandas = data tables in Python [OK]

Common Mistakes:

• Confusing pandas with graphics or web tools
• Thinking pandas is for system programming

2. Which of these is the correct way to import pandas in Python?

easy

A. import pandas as pn

B. import pandas as pd

C. from pandas import table

D. import panda as pd

Solution

1. Step 1: Recall pandas import convention

   The common and correct way is to import pandas as pd for short.

2. Step 2: Check each option

   import pandas as pd matches the standard import. Others have wrong names or syntax.

3. Final Answer:

   import pandas as pd -> Option B

4. Quick Check:

   Standard import = import pandas as pd [OK]

Hint: Use 'import pandas as pd' always [OK]

Common Mistakes:

• Misspelling 'pandas' as 'panda'
• Using wrong alias like 'pn'
• Trying to import non-existent modules

3. What will this code print?

import pandas as pd
data = {'A': [1, 2], 'B': [3, 4]}
df = pd.DataFrame(data)
print(df)

medium

A. A table with columns A and B showing values 1,2 and 3,4

B. A list of dictionaries

C. An error because DataFrame is not defined

D. Empty output

Solution

1. Step 1: Create DataFrame from dictionary

   The dictionary has keys 'A' and 'B' with lists as values. pd.DataFrame converts this into a table with columns A and B.

2. Step 2: Print DataFrame

   Printing df shows a table with two rows: first row 1 and 3, second row 2 and 4 under columns A and B.

3. Final Answer:

   A table with columns A and B showing values 1,2 and 3,4 -> Option A

4. Quick Check:

   DataFrame prints table = A table with columns A and B showing values 1,2 and 3,4 [OK]

Hint: DataFrame from dict shows columns and rows [OK]

Common Mistakes:

• Thinking it prints a list or dictionary
• Expecting an error without importing pandas
• Assuming empty output

4. Find the error in this code:

import pandas as pd
data = {'X': [5, 6], 'Y': [7, 8]}
df = pd.Dataframe(data)
print(df)

medium

A. Typo in DataFrame capitalization

B. Missing import statement

C. Dictionary keys must be strings

D. print() function is incorrect

Solution

1. Step 1: Check pandas DataFrame spelling

   The correct class name is DataFrame with a capital 'F'. The code uses Dataframe which causes an error.

2. Step 2: Verify other parts

   Import is correct, dictionary keys are strings, and print() is used properly.

3. Final Answer:

   Typo in DataFrame capitalization -> Option A

4. Quick Check:

   Class name is DataFrame, not Dataframe [OK]

Hint: Check capitalization of DataFrame class [OK]

Common Mistakes:

• Writing Dataframe instead of DataFrame
• Ignoring case sensitivity in Python
• Assuming print() causes error

5. You have a CSV file with sales data. Which pandas function helps you load this file into a DataFrame for analysis?

hard

A. pd.load_file()

B. pd.open_csv()

C. pd.read_csv()

D. pd.import_csv()

Solution

1. Step 1: Identify pandas function for CSV files

   Pandas provides read_csv() to load CSV files into DataFrames easily.

2. Step 2: Check options for correctness

   Only pd.read_csv() is a valid pandas function. Others do not exist.

3. Final Answer:

   pd.read_csv() -> Option C

4. Quick Check:

   CSV load = pd.read_csv() [OK]

Hint: Use pd.read_csv() to load CSV files [OK]

Common Mistakes:

• Using non-existent pandas functions
• Confusing with file open methods
• Trying to load CSV without pandas