Array creation (array, arange, linspace) in Data Analysis Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the numpy.array() function do?

It creates a new array from a list or sequence of numbers. This array can be used for fast math and data operations.

beginner

How does numpy.arange() differ from Python's built-in range()?

numpy.arange() can create arrays with decimal steps, not just whole numbers like range(). It returns a NumPy array instead of a list.

beginner

What is the purpose of numpy.linspace()?

It creates an array of evenly spaced numbers between a start and stop value, including the stop value. You specify how many numbers you want.

intermediate

Example: What does np.arange(1, 5, 0.5) produce?

It creates an array starting at 1, increasing by 0.5, up to but not including 5: [1. , 1.5, 2. , 2.5, 3. , 3.5, 4. , 4.5]

intermediate

Why might you choose linspace() over arange()?

Because linspace() lets you specify the exact number of points you want between start and stop, which is helpful for precise spacing. arange() uses step size, which can cause rounding issues.

Which function creates an array with a specific number of evenly spaced points between two values?

A numpy.array()

B numpy.linspace()

C numpy.arange()

D Python range()

numpy.linspace() creates a fixed number of points evenly spaced between start and stop.

What will np.arange(0, 3, 1) output?

A [0, 1, 2]

B [1, 2, 3]

C [0, 1, 2, 3]

D [0, 1, 2, 3, 4]

np.arange() includes start but excludes stop, so it stops before 3.

Which function converts a Python list into a NumPy array?

A numpy.array()

B numpy.arange()

C numpy.tolist()

D numpy.linspace()

numpy.array() takes a list and returns a NumPy array.

If you want 5 numbers evenly spaced from 0 to 1, which function and parameters would you use?

A np.array([0, 0.2, 0.4, 0.6, 0.8])

B np.arange(0, 1, 0.2)

C np.linspace(0, 1, 5)

D np.arange(0, 1, 0.25)

np.linspace(0, 1, 5) creates exactly 5 points evenly spaced between 0 and 1.

What type of object do numpy.array(), arange(), and linspace() return?

A Python list

B Dictionary

C Tuple

D NumPy array

All these functions return a NumPy array, which is optimized for math and data tasks.

Explain how to create a NumPy array from a Python list and why you might want to do this.

Think about turning simple lists into powerful arrays for calculations.

Describe the difference between arange() and linspace() and when to use each.

Focus on how you control the spacing and number of points.