How Can I Use Python Dictionary Comprehensions to Create and Modify Dictionaries?

Python Dictionary Comprehension

In Python, dictionary comprehensions are available to create new dictionaries from existing ones. However, unlike list comprehensions, they cannot be used to modify existing dictionaries.

One can utilize dictionary comprehensions to specify both keys and values. As illustrated below:

d = {n: n**2 for n in range(5)}
print(d)  # Output: {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

Another application of dictionary comprehensions is setting each key to a consistent value. For example, following snippet sets all keys to "True":

d = {n: True for n in range(5)}
print(d)  # Output: {0: True, 1: True, 2: True, 3: True, 4: True}

In cases where one desires to adjust keys for an existing dictionary, it is necessary to either loop through each key or create a new dictionary using a dictionary comprehension and update the existing one using "update" method.

The above is the detailed content of How Can I Use Python Dictionary Comprehensions to Create and Modify Dictionaries?. For more information, please follow other related articles on the PHP Chinese website!