Series creation from lists and dicts in Data Analysis Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Series from list with custom index

What is the output of this code creating a pandas Series from a list with a custom index?

Data Analysis Python

import pandas as pd
s = pd.Series([10, 20, 30], index=['a', 'b', 'c'])
print(s)

A

a    10
b    20
c    30
dtype: object

B

0    10
1    20
2    30
dtype: int64

C

a    10
b    20
c    30
Name: None, dtype: int64

D

a    10
b    20
c    30
dtype: int64

💡 Hint

Check how the index parameter changes the labels of the Series.

The Series is created with values [10, 20, 30] and index labels ['a', 'b', 'c']. The dtype is int64 because the values are integers.

❓ data_output

intermediate

Length of Series from dict with missing keys

What is the length of the Series created from this dictionary with a specified index containing keys not in the dict?

Data Analysis Python

import pandas as pd
d = {'x': 1, 'y': 2}
s = pd.Series(d, index=['x', 'y', 'z'])
print(len(s))

A 2

B 3

C KeyError

D 1

💡 Hint

Series length matches the index length, even if some keys are missing in the dict.

The Series has index ['x', 'y', 'z'], so length is 3. The missing key 'z' gets a NaN value but counts as an element.

🔧 Debug

advanced

Identify the error in Series creation from dict with list values

What error does this code raise when creating a Series from a dictionary with list values?

Data Analysis Python

import pandas as pd
d = {'a': [1, 2], 'b': [3, 4]}
s = pd.Series(d)
print(s)

A No error, prints the Series with lists as values

B ValueError: arrays must be same length

C TypeError: unhashable type: 'list'

D KeyError: 'a'

💡 Hint

Check if pandas allows lists as values in Series from dict.

Pandas allows lists as values in Series from dict. The Series will have keys as index and lists as values without error.

🧠 Conceptual

advanced

Behavior of Series creation from dict with partial index

When creating a pandas Series from a dictionary with a specified index that includes keys not in the dictionary, what value does pandas assign to those missing keys?

A It assigns NaN (Not a Number) to missing keys in the Series.

B It raises a KeyError and stops execution.

C It assigns zero (0) to missing keys automatically.

D It ignores missing keys and creates Series only with existing keys.

💡 Hint

Think about how pandas handles missing data in Series.

Pandas assigns NaN to any index label not found in the dictionary when creating a Series with a specified index.

🚀 Application

expert

Create Series from dict with mixed types and analyze output

Given this dictionary with mixed value types, what is the dtype of the resulting Series?

Data Analysis Python

import pandas as pd
d = {'a': 1, 'b': 2.5, 'c': '3'}
s = pd.Series(d)
print(s.dtype)

A int64

B float64

C object

D string

💡 Hint

Consider how pandas handles mixed data types in a Series.

When a Series has mixed types (int, float, string), pandas uses dtype 'object' to hold all types.