How to convert NumPy array to dictionary in Python?
Last Updated :
26 Feb, 2023
The following article explains how to convert numpy array to dictionary in Python. Array in Numpy is a table of elements (usually numbers), all of the same type, indexed by a tuple of positive integers. In Numpy, number of dimensions of the array is called rank of the array. A tuple of integers giving the size of the array along each dimension is known as shape of the array. An array class in Numpy is called as ndarray. Elements in Numpy arrays are accessed by using square brackets and can be initialized by using nested Python Lists.
Approach
To convert a numpy array to dictionary the following program uses dict(enumerate(array.flatten(), 1)) and this is what it exactly does:
- array.flatten: This function is used to get a copy of given array, collapsed into one dimension.
- enumerate: Enumerate method comes with an automatic counter/index for each of the items present in the list. The first index value will start from 0
- dict: this function is used to convert any object to dictionary.
Example 1:
Python3
# importing required libraries
import numpy as np
# creating a numpy array
array = np.array([['a', 'b', 'c'],
['d', 'e', 'f'],
['g', 'h', 'i']])
# convert numpy array to dictionary
d = dict(enumerate(array.flatten(), 1))
# print numpy array
print(array)
print(type(array))
# print dictionary
print(d)
print(type(d))
Output:
[['a' 'b' 'c']
['d' 'e' 'f']
['g' 'h' 'i']]
<class 'numpy.ndarray'>
{1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e', 6: 'f', 7: 'g', 8: 'h', 9: 'i'}
<class 'dict'>
Time Complexity: The time complexity for converting a numpy array to a dictionary is O(n), where n is the number of elements in the numpy array.
Space Complexity: The space complexity for converting a numpy array to a dictionary is O(n), where n is the number of elements in the numpy array.
Example 2:
Python3
# importing required libraries
import numpy as np
# creating a numpy array
array = np.array([['1', '2', '3','4','5'],
['6', '7', '8','9','10'],
['11', '12', '13','14','15']])
# convert numpy array to dictionary
d = dict(enumerate(array.flatten(), 1))
# print numpy array
print(array)
print(type(array))
# print dictionary
print(d)
print(type(d))
Output:
[['1' '2' '3' '4' '5']
['6' '7' '8' '9' '10']
['11' '12' '13' '14' '15']]
<class 'numpy.ndarray'>
{1: '1', 2: '2', 3: '3', 4: '4', 5: '5', 6: '6', 7: '7', 8: '8', 9: '9', 10: '10', 11: '11', 12: '12', 13: '13', 14: '14', 15: '15'}
<class 'dict'>
Time complexity: O(n), where n is the number of elements in the numpy array.
Auxiliary space: O(n), where n is the number of elements in the numpy array, due to the creation of the dictionary.
Similar Reads
Ways to Convert a Python Dictionary to a NumPy Array The task of converting a dictionary to a NumPy array involves transforming the dictionaryâs key-value pairs into a format suitable for NumPy. In Python, there are different ways to achieve this conversion, depending on the structure and organization of the resulting array.For example, consider a dic
3 min read
How to Convert a Dictionary into a NumPy Array In this article, we will learn how to convert a Python Dictionary into a numpy array which is more efficient for numerical operations and provides powerful tools for matrix and array manipulationsKey Steps to Convert a Dictionary to a NumPy ArrayUse dict.items(): This returns key-value pairs from th
3 min read
Convert Python List to numpy Arrays NumPy arrays are more efficient than Python lists, especially for numerical operations on large datasets. NumPy provides two methods for converting a list into an array using numpy.array() and numpy.asarray(). In this article, we'll explore these two methods with examples for converting a list into
4 min read
How to convert NumPy array to list ? This article will guide you through the process of convert a NumPy array to a list in Python, employing various methods and providing detailed examples for better understanding. Convert NumPy Array to List There are various ways to convert NumPy Array to List here we are discussing some generally us
4 min read
How to Convert NumPy Matrix to Array In NumPy, a matrix is essentially a two-dimensional NumPy array with a special subclass. In this article, we will see how we can convert NumPy Matrix to Array. Also, we will see different ways to convert NumPy Matrix to Array. Convert Python NumPy Matrix to an ArrayBelow are the ways by which we can
3 min read
How to Convert images to NumPy array? Pictures on a computer are made of tiny dots called pixels. To work with them in Python, we convert them into numbers using a NumPy array is a table of numbers showing each pixelâs color. In this article, weâll learn how to do this using popular Python tools.Loading the images via Pillow LibraryLet
5 min read