How to create an array in Python?-Python Tutorial-php.cn

How to create an array in Python?

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Release： 2023-09-21 13:25:02

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How to create an array in Python?

Arrays in Python are ndarray objects. To create arrays in Python, use the Numpy library. An array is a container that can hold a fixed number of elements, and these elements should be of the same type. To use arrays in Python, import the NumPy library.

First, let’s install the Numpy library -

pip install numpy

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Import the required Numpy libraries -

import numpy as np

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Create array

Example

Now let's create an array. Basic Numpy arrays are created using the array() function in NumPy -

import numpy as np
# Create a Numpy Array
arr = np.array([5, 10, 15, 20, 25])
print("Array = ",arr)

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Output

Array =  [ 5 10 15 20 25]

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Create a two-dimensional array

Example

We will create a two-dimensional array, a matrix. Here, a 2x3 matrix will be created -

import numpy as np

# Create a Numpy Matrix 2x3
a = np.array([[5, 10, 15], [20, 25, 30]])

# Display the array with more than one dimension
print("Array = ",a)

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Output

Array =  [[ 5 10 15]
         [20 25 30]]

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Get array dimensions

Example

To get array dimensions in Python, use numpy.ndim. For a one-dimensional array, the dimension is 1.

Similarly, for a 2D array, the dimensions will be 2, etc. Now let's look at an example -

import numpy as np

# Create a Numpy Matrix 2x3
arr = np.array([[5, 10, 15], [20, 25, 30]])

# Display the array with more than one dimension
print("Array = \n",arr)
print("Array Dimensions = ",arr.ndim)

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Output

Array = 
[[ 5 10 15]
 [20 25 30]]
Array Dimensions =  2

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Get the shape of the array

Example

The number of elements in each dimension of an array is called its shape. Use numpy.shape to get the array shape. Let's see an example of getting the shape of an array -

import numpy as np

# Create a Numpy Matrix 2x3
arr = np.array([[5, 10, 15], [20, 25, 30]])

# Display the array
print("Array = \n",arr)
print("Array Shape = ",arr.shape)

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Output

Array = 
[[ 5 10 15]
 [20 25 30]]
Array Shape =  (2, 3)

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Initialize array with zeros

Example

We can easily initialize Numpy arrays with zeros -

import numpy as np

# Create a Numpy Matrix 3x3 with zeros
arr = np.zeros([3, 3])

# Display the array
print("Array = \n",arr)
print("Array Shape = ",arr.shape)

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Output

Array = 
[[0. 0. 0.]
 [0. 0. 0.]
 [0. 0. 0.]]
Array Shape =  (3, 3)

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Sort the array

Example

To sort an array in Numpy, use the sort() method -

import numpy as np

# Create a Numpy Matrix
arr = np.array([[5, 3, 8], [17, 25, 12]])

# Display the array
print("Array = \n",arr)

# Sort the array
print("\nSorted array = \n", np.sort(arr))

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Output

Array = 
[[ 5  3  8]
 [17 25 12]]
Sorted array = 
[[ 3  5  8]
 [12 17 25]]

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