DA Data Analysis Tools and Programming 3

Question 1

What does the pandas .fillna() method do?

Accepted Answer

Fills missing NaN values with a specified value or method

Answer

fillna() replaces NaN values in a DataFrame with a specified scalar, dictionary, or forward/backward fill method.

Question 2

What is the purpose of Excel's IF function?

Accepted Answer

Returns one value if a condition is true and another if it is false

Answer

The IF function tests a logical condition and returns the 'true value' if met or the 'false value' if not.

Question 3

Which Python library is most commonly used for data visualization?

Accepted Answer

Matplotlib

Answer

Matplotlib is the foundational Python visualization library used to create line charts, bar charts, scatter plots, and more.

Question 4

What does 'vectorization' mean in the context of pandas or NumPy?

Accepted Answer

Applying operations to entire arrays without explicit Python loops

Answer

Vectorization applies operations element-wise across arrays using optimized C-level code, making computations significantly faster than Python loops.

Question 5

What is the purpose of Excel's SUMIF function?

Accepted Answer

Sums cells in a range that meet a specified condition

Answer

SUMIF adds the values in a range only for rows where a specified condition is true.

DA - Data Analyst Practice Test