Data Science Data Cleaning and Preparation 5

Question 1

Combining two DataFrames on a shared key column in pandas is done with:

Accepted Answer

pd.merge()

Answer

pd.merge joins DataFrames on common key columns.

Question 2

An 'inner join' between two tables returns:

Accepted Answer

Only rows with matching keys in both tables

Answer

An inner join keeps only keys present in both tables.

Question 3

MICE (Multiple Imputation by Chained Equations) is a method for:

Accepted Answer

Imputing missing values using other features

Answer

MICE models each feature with missing data from the others to impute values.

Question 4

Reshaping data from wide to long format in pandas typically uses:

Accepted Answer

pd.melt()

Answer

pd.melt unpivots wide columns into long key-value rows.

Question 5

When categorical labels have a natural order (low, medium, high), the best encoding is:

Accepted Answer

Ordinal encoding

Answer

Ordinal encoding preserves the inherent rank order of categories.

Data Science Practice Test