JIYIK CN >

Python dictionaries are ordered and mutable. Dictionaries do not allow duplicate entries to be stored.

In Python 3.6 and below, dictionaries used to be unordered. After the introduction of Python 3.7+, dictionaries are sorted.

This tutorial will discuss different ways to initialize dictionaries in Python.

Initializing a dictionary in Python using literal syntax

{}Dictionaries are created and initialized using curly braces , which contain keys and values.

The following code initializes a Python dictionary using a literal.

dict1 = {"X": 2, "Y": 3, "Z": 4}
print(dict1)

Output:

{'X': 2, 'Y': 3, 'Z': 4}

Initializing a Python dictionary using dict()the constructor

dict()The constructor can be used to initialize a dictionary from keyword arguments, a separate dictionary and its keyword arguments, or a separate iterable of key-value pairs.

We can dict()pass arguments in the constructor and create a dictionary.

The following code uses dict()the constructor to initialize a dictionary in Python.

dict1 = dict(X=1, Y=2, Z=3)
print(dict1)

Output:

{'X': 1, 'Y': 2, 'Z': 3}

fromkeys()Initialize a Python dictionary using the

If all keys have the same value, you can use fromkeys()the function.

The following code uses fromkeys()the method to initialize a Python dictionary.

dict1 = dict.fromkeys(["X", "Y", "Z"], 0)
print(dict1)

Output:

{'X': 0, 'Y': 0, 'Z': 0}

If no specific value is specified in the syntax, the dictionary is initialized with values ​​for all keys None.

dict1 = dict.fromkeys(["X", "Y", "Z"])
print(dict1)

Output:

{'X': None, 'Y': None, 'Z': None}

Initializing a Python dictionary using a list of tuples

Lists of tuples can also be used to initialize dictionaries in Python. This method also uses dict()the constructor to achieve this.

A tuple is an ordered and immutable collection of objects. It can be used to store multiple items in a single variable.

Lists are similar to tuples, the only difference is that lists can be changed, while tuples do not allow this.

The following code initializes a dictionary in Python using a list of tuples.

LOT = [("X", 5), ("Y", 6), ("Z", 8)]
dict1 = dict(LOT)
print(dict1)

Output:

{'X': 5, 'Y': 6, 'Z': 8}

Initializing a Python dictionary using two lists

In this case, we declare two lists where the values ​​of the first list are used as keys and the second list is used as the values ​​of the dictionary we are going to initialize.

To implement the above statement, we can use zip()the function, which iterates over two given lists in parallel.

zip()The function will create a key-value pair for all entries in parallel and will successfully create a compressed object which can then be passed to dict()the constructor to create a dictionary.

The following code uses two lists to initialize a dictionary in Python.

if __name__ == "__main__":

    L1 = ["X", "Y", "Z"]
    L2 = [5, 6, 8]
    dict1 = dict(zip(L1, L2))
    print(dict1)

Output:

{'X': 5, 'Y': 6, 'Z': 8}

In this case, L1 is the list used as keys and L2 is the list used as values ​​for the initialized dictionary.