head() and tail() for previewing in Pandas - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of head() with n=3?

Given the DataFrame below, what will df.head(3) return?

Pandas

import pandas as pd

data = {'Name': ['Anna', 'Bob', 'Cathy', 'David', 'Eva'], 'Age': [23, 35, 45, 28, 32]}
df = pd.DataFrame(data)
print(df.head(3))

A

   Name  Age
2 Cathy   45
3 David   28
4   Eva   32

B

   Name  Age
3 David   28
4   Eva   32

C

   Name  Age
0  Anna   23
1   Bob   35
2 Cathy   45
3 David   28
4   Eva   32

D

   Name  Age
0  Anna   23
1   Bob   35
2 Cathy   45

💡 Hint

head(n) shows the first n rows of the DataFrame.

The head(3) method returns the first 3 rows of the DataFrame, which are rows with index 0, 1, and 2.

❓ Predict Output

intermediate

What does tail() return by default?

Given the DataFrame below, what will df.tail() return?

Pandas

import pandas as pd

data = {'City': ['NY', 'LA', 'Chicago', 'Houston', 'Phoenix'], 'Population': [8.4, 4.0, 2.7, 2.3, 1.7]}
df = pd.DataFrame(data)
print(df.tail())

A

   City  Population
3 Houston       2.3
4 Phoenix       1.7

B

   City  Population
2 Chicago       2.7
3 Houston       2.3
4 Phoenix       1.7

C

   City  Population
0    NY         8.4
1    LA         4.0
2 Chicago       2.7
3 Houston       2.3
4 Phoenix       1.7

D

   City  Population
0    NY         8.4
1    LA         4.0

💡 Hint

tail() without argument returns the last 5 rows by default.

The DataFrame has 5 rows total. tail() returns the last 5 rows by default, which is the entire DataFrame here.

❓ data_output

advanced

How many rows does df.head(0) return?

Consider the DataFrame below. What is the number of rows in df.head(0)?

Pandas

import pandas as pd

data = {'Product': ['A', 'B', 'C', 'D'], 'Price': [10, 20, 30, 40]}
df = pd.DataFrame(data)
print(len(df.head(0)))

A 0

B 1

C 4

D Raises an error

💡 Hint

head(0) means show zero rows from the top.

head(0) returns an empty DataFrame with zero rows but same columns.

❓ Predict Output

advanced

What is the output of df.tail(2) on a 6-row DataFrame?

Given the DataFrame below, what will df.tail(2) output?

Pandas

import pandas as pd

data = {'Letter': ['a', 'b', 'c', 'd', 'e', 'f'], 'Number': [1, 2, 3, 4, 5, 6]}
df = pd.DataFrame(data)
print(df.tail(2))

A

  Letter  Number
4      e       5
5      f       6

B

  Letter  Number
0      a       1
1      b       2

C

  Letter  Number
3      d       4
4      e       5

D

  Letter  Number
5      f       6

💡 Hint

tail(2) returns the last two rows.

The last two rows have index 4 and 5 with letters 'e' and 'f'.

🧠 Conceptual

expert

Which statement about head() and tail() is TRUE?

Select the correct statement about head() and tail() methods in pandas.

A head(n) returns the last n rows; tail(n) returns the first n rows of a DataFrame.

B head(n) returns the first n rows; tail(n) returns the last n rows of a DataFrame.

C head() and tail() both return the entire DataFrame regardless of n.

D head() returns rows randomly; tail() returns rows sorted by index.

💡 Hint

Think about what 'head' and 'tail' mean in everyday life.

head(n) returns the first n rows, like the start of a list. tail(n) returns the last n rows, like the end of a list.