Data Science with Python Certification Data Science with Python Pandas DataFrame Operations 5

Question 1

What does df.resample('M').sum() require the DataFrame's index to be?

Accepted Answer

A DatetimeIndex

Answer

resample() is a time-based groupby and requires the index to be a DatetimeIndex.

Question 2

Which of the following creates a DataFrame with a MultiIndex from a groupby result?

Accepted Answer

df.groupby(['city','dept']).mean()

Answer

Grouping by multiple columns without reset_index() yields a DataFrame with a MultiIndex on the rows.

Question 3

What is the effect of df.clip(lower=0, upper=100) on a DataFrame?

Accepted Answer

Replaces values below 0 with 0 and above 100 with 100

Answer

clip() caps values at the specified lower and upper bounds without removing any rows.

Question 4

How do you stack the innermost column level of a DataFrame with MultiIndex columns to rows?

Accepted Answer

df.stack()

Answer

stack() pivots the innermost column level into the innermost row level, creating a taller DataFrame.

Question 5

What does df.nlargest(5, 'revenue') return?

Accepted Answer

The 5 rows with the largest revenue values, sorted descending

Answer

nlargest(n, column) selects the n rows with the highest values in the specified column, sorted in descending order.

Data Science with Python Certification Practice Test