np.random.rand() and random arrays in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does np.random.rand() do?

It creates an array of random numbers between 0 and 1, with the shape you specify.

beginner

How do you create a 2x3 array of random numbers using np.random.rand()?

Use np.random.rand(2, 3). This makes 2 rows and 3 columns of random numbers between 0 and 1.

beginner

What range of values does np.random.rand() generate?

It generates numbers from 0 (inclusive) up to 1 (exclusive). So, numbers are always >= 0 and < 1.

intermediate

How is np.random.rand() different from np.random.randn()?

np.random.rand() generates uniform random numbers between 0 and 1, while np.random.randn() generates numbers from a normal (bell curve) distribution centered at 0.

beginner

Why might you use np.random.rand() in data science?

To create random samples or initialize arrays for simulations, testing algorithms, or creating random data for experiments.

What does np.random.rand(4, 2) produce?

A A 4x2 array of random numbers between 0 and 1

B A 2x4 array of random integers

C A 4x2 array of zeros

D A 4x2 array of random numbers from a normal distribution

np.random.rand(4, 2) creates a 4 rows by 2 columns array with random floats between 0 and 1.

Which of these is true about numbers from np.random.rand()?

A They follow a normal distribution

B They are always between 0 and 1, including 1

C They can be negative

D They are always between 0 and 1, excluding 1

Numbers from np.random.rand() are >= 0 and < 1, so 1 is excluded.

How to create a 1D array with 5 random numbers using np.random.rand()?

A <code>np.random.rand(1,5)</code>

B <code>np.random.rand(5)</code>

C <code>np.random.rand(5,1)</code>

D <code>np.random.rand()</code>

np.random.rand(5) creates a 1D array with 5 random numbers.

What is the difference between np.random.rand() and np.random.randint()?

A Both generate floats

B Both generate integers

C <code>rand()</code> generates floats, <code>randint()</code> generates integers

D <code>rand()</code> generates integers, <code>randint()</code> generates floats

np.random.rand() generates floats between 0 and 1, while np.random.randint() generates random integers.

If you want a 3D array of random numbers with shape (2, 3, 4), how do you call np.random.rand()?

A <code>np.random.rand(2, 3, 4)</code>

B <code>np.random.rand(3, 4, 2)</code>

C <code>np.random.rand(2*3*4)</code>

D <code>np.random.rand([2, 3, 4])</code>

You pass each dimension as a separate argument: np.random.rand(2, 3, 4).

Explain how to create a 2D array of random numbers between 0 and 1 using np.random.rand(). Include how to specify the shape.

Think about rows and columns as arguments.

Describe the difference between np.random.rand() and np.random.randn() and when you might use each.

Consider the shape of the number distribution.