Зміст курсу
Ultimate NumPy
Ultimate NumPy
Basic Indexing
Every NumPy array has elements and their respective indices. Here we will focus on indices in 1D arrays. Let's take a look at the following image:
Here we have an array of five elements: [9, 6, 4, 8, 10]. Every element has a positive and negative index. For example, 9 has 0 as its positive index and -5 as its negative index. As you can see, positive indexing in arrays starts at 0 and goes up to n-1, where n is the length of the array. Negative indexing, on the other hand, starts at -n and goes up to -1.
Accessing Elements by Indices
To access an element by its index, you should specify the index of this element in square brackets, e.g., array[2].
Note
If a specified index is out of bounds, an
IndexErroris thrown, so be cautious of that.
Let's take a look at an example:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Accessing the first element (positive index) print(f'The first element (positive index): {array[0]}') # Accessing the first element (negative index) print(f'The first element (negative index): {array[-5]}') # Accessing the last element (positive index) print(f'The last element (positive index): {array[4]}') # Accessing the last element (negative index) print(f'The last element (negative index): {array[-1]}') # Accessing the third element (positive index) print(f'The third element (positive index): {array[2]}') # Accessing the third element (negative index) print(f'The third element (negative index): {array[-3]}')
As you can see, there is nothing complicated here.
Note
It is common practice to access the first element of the array using a positive index (
0) and the last element using a negative index (-1).
Since the elements of our array are just numbers, we can perform all kinds of operations on them that we would do with regular numbers:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Finding the average between the first and the last element print((array[0] + array[-1]) / 2)
Here, we calculated the average of the first and the last elements of our array.
Завдання
Calculate the average of the first, fourth, and last elements:
- Use a positive index to access the first element.
- Use a positive index to access the fourth element.
- Use a negative index to access the last element.
- Calculate the average of these numbers.
Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантівДякуємо за ваш відгук!
Basic Indexing
Every NumPy array has elements and their respective indices. Here we will focus on indices in 1D arrays. Let's take a look at the following image:
Here we have an array of five elements: [9, 6, 4, 8, 10]. Every element has a positive and negative index. For example, 9 has 0 as its positive index and -5 as its negative index. As you can see, positive indexing in arrays starts at 0 and goes up to n-1, where n is the length of the array. Negative indexing, on the other hand, starts at -n and goes up to -1.
Accessing Elements by Indices
To access an element by its index, you should specify the index of this element in square brackets, e.g., array[2].
Note
If a specified index is out of bounds, an
IndexErroris thrown, so be cautious of that.
Let's take a look at an example:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Accessing the first element (positive index) print(f'The first element (positive index): {array[0]}') # Accessing the first element (negative index) print(f'The first element (negative index): {array[-5]}') # Accessing the last element (positive index) print(f'The last element (positive index): {array[4]}') # Accessing the last element (negative index) print(f'The last element (negative index): {array[-1]}') # Accessing the third element (positive index) print(f'The third element (positive index): {array[2]}') # Accessing the third element (negative index) print(f'The third element (negative index): {array[-3]}')
As you can see, there is nothing complicated here.
Note
It is common practice to access the first element of the array using a positive index (
0) and the last element using a negative index (-1).
Since the elements of our array are just numbers, we can perform all kinds of operations on them that we would do with regular numbers:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Finding the average between the first and the last element print((array[0] + array[-1]) / 2)
Here, we calculated the average of the first and the last elements of our array.
Завдання
Calculate the average of the first, fourth, and last elements:
- Use a positive index to access the first element.
- Use a positive index to access the fourth element.
- Use a negative index to access the last element.
- Calculate the average of these numbers.
Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантівДякуємо за ваш відгук!
Basic Indexing
Every NumPy array has elements and their respective indices. Here we will focus on indices in 1D arrays. Let's take a look at the following image:
Here we have an array of five elements: [9, 6, 4, 8, 10]. Every element has a positive and negative index. For example, 9 has 0 as its positive index and -5 as its negative index. As you can see, positive indexing in arrays starts at 0 and goes up to n-1, where n is the length of the array. Negative indexing, on the other hand, starts at -n and goes up to -1.
Accessing Elements by Indices
To access an element by its index, you should specify the index of this element in square brackets, e.g., array[2].
Note
If a specified index is out of bounds, an
IndexErroris thrown, so be cautious of that.
Let's take a look at an example:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Accessing the first element (positive index) print(f'The first element (positive index): {array[0]}') # Accessing the first element (negative index) print(f'The first element (negative index): {array[-5]}') # Accessing the last element (positive index) print(f'The last element (positive index): {array[4]}') # Accessing the last element (negative index) print(f'The last element (negative index): {array[-1]}') # Accessing the third element (positive index) print(f'The third element (positive index): {array[2]}') # Accessing the third element (negative index) print(f'The third element (negative index): {array[-3]}')
As you can see, there is nothing complicated here.
Note
It is common practice to access the first element of the array using a positive index (
0) and the last element using a negative index (-1).
Since the elements of our array are just numbers, we can perform all kinds of operations on them that we would do with regular numbers:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Finding the average between the first and the last element print((array[0] + array[-1]) / 2)
Here, we calculated the average of the first and the last elements of our array.
Завдання
Calculate the average of the first, fourth, and last elements:
- Use a positive index to access the first element.
- Use a positive index to access the fourth element.
- Use a negative index to access the last element.
- Calculate the average of these numbers.
Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантівДякуємо за ваш відгук!
Every NumPy array has elements and their respective indices. Here we will focus on indices in 1D arrays. Let's take a look at the following image:
Here we have an array of five elements: [9, 6, 4, 8, 10]. Every element has a positive and negative index. For example, 9 has 0 as its positive index and -5 as its negative index. As you can see, positive indexing in arrays starts at 0 and goes up to n-1, where n is the length of the array. Negative indexing, on the other hand, starts at -n and goes up to -1.
Accessing Elements by Indices
To access an element by its index, you should specify the index of this element in square brackets, e.g., array[2].
Note
If a specified index is out of bounds, an
IndexErroris thrown, so be cautious of that.
Let's take a look at an example:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Accessing the first element (positive index) print(f'The first element (positive index): {array[0]}') # Accessing the first element (negative index) print(f'The first element (negative index): {array[-5]}') # Accessing the last element (positive index) print(f'The last element (positive index): {array[4]}') # Accessing the last element (negative index) print(f'The last element (negative index): {array[-1]}') # Accessing the third element (positive index) print(f'The third element (positive index): {array[2]}') # Accessing the third element (negative index) print(f'The third element (negative index): {array[-3]}')
As you can see, there is nothing complicated here.
Note
It is common practice to access the first element of the array using a positive index (
0) and the last element using a negative index (-1).
Since the elements of our array are just numbers, we can perform all kinds of operations on them that we would do with regular numbers:
import numpy as np array = np.array([9, 6, 4, 8, 10]) # Finding the average between the first and the last element print((array[0] + array[-1]) / 2)
Here, we calculated the average of the first and the last elements of our array.
Завдання
Calculate the average of the first, fourth, and last elements:
- Use a positive index to access the first element.
- Use a positive index to access the fourth element.
- Use a negative index to access the last element.
- Calculate the average of these numbers.
Перейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантівПерейдіть на комп'ютер для реальної практикиПродовжуйте з того місця, де ви зупинились, використовуючи один з наведених нижче варіантів