Data Science Data Cleaning and Preparation 2

Question 1

In pandas, what does df.dropna(thresh=3) do?

Accepted Answer

Drops rows that have fewer than 3 non-null values

Answer

thresh keeps only rows with at least 3 non-null values, dropping those below the threshold.

Question 2

Which technique replaces missing numeric values with the column average?

Accepted Answer

Mean imputation

Answer

Mean imputation fills missing values using the column's average.

Question 3

A 'duplicate record' in a dataset is best defined as a row that:

Accepted Answer

Has identical values across the columns used to identify uniqueness

Answer

Duplicates are rows matching on the key columns that define a unique record.

Question 4

Which pandas method removes duplicate rows?

Accepted Answer

df.drop_duplicates()

Answer

drop_duplicates() removes repeated rows from a DataFrame.

Question 5

Converting a column stored as text '2024-01-15' into a datetime type is an example of:

Accepted Answer

Type casting / parsing

Answer

Changing a string into a datetime is type casting or parsing.

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