10 NymPy

Question 1

What is NumPy?

Answer 1

It’s a module in Python that provides optimized functions for numerial computations. It provides a large range of functions for performing scientific computations and handling array data.
It mainly deals with multidimensional array data based on the “numpy.ndarray” object.

Question 2

How are array elements stored in NumPy?

Answer 2

as one block with contiguous addresses in memory

Question 3

What’s the difference between how Python stores an element in a list and how NumPy stores an element in an array?

Answer 3

In Python, an element in a list is a reference to an object.
In NumPy, an element in an array is a bit pattern of the stored value (not a reference to it but the value itself in form of bits)

Question 4

True or False: Just like lists in Python, an array in NumPy can hold any kind of data type.

Answer 4

False. All elements in an NumPy array have the same data type.

Question 5

How are multidimensional arrays stored in NumPy?

Answer 5

NumPy flattens all arrays in the background and stores them as 1-dimensional array.

Question 6

What does row-major/column-major order mean, in regards to storing multidimensional arrays in NumPy?

Answer 6

row-major order: consecutive elements of a row reside next to each other (after NumPy flattening).
column-major order: consecutive elements of a column reside next to each other (after NumPy flattening).

Question 7

For a 3-dimensional array “my_array” of the shape (3, 4, 5), how can you access the element in the second depth, first row, third column?

Answer 7

my_array[1, 0, 2]

Question 8

What is the shape of an array?

Answer 8

It defines the multi-dimensionality. It tells you how many dimensions the array has and the length of them.

Question 9

What is the axis of an array?

Answer 9

It’s the dimension of the array.

Question 10

Given the provided example, answer the questions below:

[[[1 2 3]
[4 5 6]]
[[9 8 7]
[6 5 4]]]

1. How many axes does the array have?
2. What is the array’s shape?
3. What is the lenth of the first axis?

Answer 10

1. 3 axes
2. the shape is (2, 2, 3).
3. the first axis has a length of 2