Data Science with Python Certification Data Science with Python Exploratory Data Analysis 2

Question 1

Which pandas method returns the number of non-null entries for each column in a DataFrame?

Accepted Answer

df.count()

Answer

df.count() returns the count of non-null values for each column by default.

Question 2

What does a box plot's IQR represent?

Accepted Answer

The middle 50% of the data between Q1 and Q3

Answer

The IQR (Interquartile Range) is the span between the first quartile (Q1) and third quartile (Q3), covering the middle 50% of data.

Question 3

In pandas, what does df.duplicated().sum() compute?

Accepted Answer

The total number of duplicate rows in the DataFrame

Answer

df.duplicated() returns a boolean Series marking duplicate rows, and .sum() counts how many are True.

Question 4

Which seaborn plot is best for visualizing the relationship between two continuous variables along with their marginal distributions?

Accepted Answer

sns.jointplot()

Answer

sns.jointplot() shows a scatter plot of two variables plus their individual marginal histograms or KDEs.

Question 5

What is the primary purpose of using df.describe() on a DataFrame containing both numeric and object columns when include='all' is passed?

Accepted Answer

It provides summary statistics for both numeric and categorical columns

Answer

Passing include='all' forces describe() to include object columns, showing count, unique, top, and freq alongside numeric stats.

Data Science with Python Certification Practice Test