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Lära Access 2-D and 3-D Arrays | Indexing and Slicing
NumPy in a Nutshell

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Access 2-D and 3-D Arrays

Let's have a look at an example of a 2-D array with axis numbering:

Let's have a look at an example of indexing (both positive and negative) in 2-D arrays:

Let's examine the syntax of slicing: array[start_row: end_row: step_row, start_column: end_column: step_column], where:

  • start_row is the index from which row slicing begins;

  • end_row is the index where row slicing stops (note that this index is not included);

  • step_row is the parameter that specifies the intervals between row indices;

  • start_column is the index from which column slicing starts;

  • end_column is the index where column slicing ends (note that this index is not included);

  • step_column is the parameter that determines the intervals between column indices.

Now, let's refer to the following image:

Let's have a look at an example of a 3-D array with axis numbering:

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Swipe to start coding

Consider the following array: [[6, 5, 7, 8], [65, 2, 7, 9]].

  1. Retrieve the fourth element from the first part of the array [6, 5, 7, 8], and the first element from the second part of the array [65, 2, 7, 9].
  2. Multiply the obtained elements together.
  3. Display the product of the obtained elements.

Lösning

import numpy as np

# Creating array
arr = np.array([[6, 5, 7, 8], [65, 2, 7, 9]])

# 1. Get the fourth element from the first inner array
fourth_element = arr[0, 3]
# 2. Get the first element from the second inner array
first_element = arr[1, 0]

# 3. Multiplying the obtained elements
result = fourth_element * first_element
print(result)

Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 3
import numpy as np

# Creating array
arr = np.array([[6, 5, 7, 8], [65, 2, 7, 9]])

# 1. Get the fourth element from the first inner array
fourth_element = ___
# 2. Get the first element from the second inner array
first_element = ___
# 3. Multiplying the obtained elements
result = ___ * ___
print(___)

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