np.ones() for one-filled arrays in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the function np.ones() do in NumPy?

np.ones() creates a new array filled with ones. You specify the shape (size) of the array, and it returns an array where every element is 1.

beginner

How do you create a 3x3 array filled with ones using np.ones()?

Use np.ones((3, 3)). The argument is a tuple that defines the shape: 3 rows and 3 columns.

beginner

What data type does np.ones() use by default for the array elements?

By default, np.ones() creates an array of floats (floating-point numbers).

intermediate

How can you create an integer array filled with ones using np.ones()?

Use the dtype parameter: np.ones((3, 3), dtype=int) creates a 3x3 array of integer ones.

beginner

Why might you use np.ones() instead of manually creating an array of ones?

np.ones() is fast, simple, and efficient. It avoids loops and manual filling, making your code cleaner and faster.

What does np.ones((2, 4)) produce?

A A 2x4 array filled with zeros

B A 4x2 array filled with ones

C A 2x4 array filled with ones

D A 2x4 array filled with random numbers

np.ones((2, 4)) creates an array with 2 rows and 4 columns, all filled with ones.

How do you specify the data type of the array elements in np.ones()?

A Using the <code>shape</code> parameter

B Using the <code>dtype</code> parameter

C Using the <code>type</code> function after creation

D You cannot specify data type

The dtype parameter lets you set the data type, like dtype=int for integers.

What is the default data type of elements created by np.ones()?

A String

B Boolean

C Integer

D Float

By default, np.ones() creates arrays with float elements.

Which of these is a correct way to create a 1D array of five ones?

A All of the above

B <code>np.ones([5])</code>

C <code>np.ones((5,))</code>

D <code>np.ones(5)</code>

All these forms create a 1D array of length 5 filled with ones.

Why is np.ones() preferred over manually creating an array of ones with loops?

A It is faster and cleaner

B It is slower but easier

C It uses more memory

D It creates random values

np.ones() is optimized for speed and simplicity, avoiding manual loops.

Explain how to create a 2D array filled with ones using np.ones(). Include how to specify the shape and data type.

Think about the shape tuple and the dtype argument.

Describe why using np.ones() is better than creating an array of ones with a for-loop in Python.

Consider speed and code simplicity.