Python DictionariesA dictionary is a set of unordered key, value pairs. In a dictionary, the keys must be unique and they are stored in an unordered manner. Show
In this tutorial you will learn the basics of how to use the Python dictionary. By the end of the tutorial you will be able to - Create Dictionaries - Get values in a Dictionary - Add and delete elements in a Dictionary - To and For Loops in a Dictionary Creating a DictionaryLet’s try to build a
profile of three people using dictionaries. To do that you separate the key-value pairs by a colon(“:”). The keys would need to be of an immutable type, i.e., data-types for which the keys cannot be changed at runtime such as int, string, tuple, etc. The values can be of any type. Individual pairs will be separated by a comma(“,”) and the whole thing will be enclosed in curly braces( For example, you can have the fields “city”, “name,” and “food” for keys in a dictionary and assign the key,value pairs to the dictionary variable person1_information.
Get the values in a DictionaryTo get the values of a dictionary from the keys, you can directly reference the keys. To do this, you enclose the key in brackets So, in the following example, a dictionary is initialized with keys “city”, “name,” and “food” and you can retrieve the value corresponding to the key “city.”
You can also use the get method to retrieve the values in a dict. The only difference is that in the get method, you can set a default value. In direct referencing, if the key is not present, the interpreter throws KeyError.
Looping over dictionarySay, you got a dictionary, and you want to print the keys and values in it. Note that the key-words
Add elements to a dictionaryYou can add elements by updating the dictionary with a new key and then assigning the value to a new key.
Or you can combine two dictionaries to get a larger dictionary using the update method.
Delete elements of a dictionaryTo delete a key, value pair in a dictionary, you can use the
A disadvantage is that it gives KeyError if you try to delete a nonexistent key.
So, instead of the
More facts about the Python dictionaryYou can test the presence of a key using the
A dictionary in Python doesn't preserve the order. Hence, we get the following:
You see that even though "snape" was given later, it appeared at the top. Contributed by: Joydeep Bhattacharjee Which method removes all key values pair from a dictionary?To delete a key, value pair in a dictionary, you can use the del method. A disadvantage is that it gives KeyError if you try to delete a nonexistent key. So, instead of the del statement you can use the pop method.
Which method deletes a key value pair from a dictionary in Python?Using pop()
The in-built function pop() deletes a specific key: value pair from a dictionary. The function takes two arguments: key : the key of the value that needs to be deleted.
How do I remove all keys from a dictionary?Method 2: Delete all Keys from a Dictionary using dict. clear() The clear() method removes all items from the dictionary. The clear() method doesn't return any value.
How do you use Del in a dictionary?The “del” keyword is used to delete a key that does exist. It raises a KeyError if a key is not present in a dictionary. We use the indexing notation to retrieve the item from the dictionary we want to remove. “key” represents the name of the key whose key-value pair we want to remove from the dictionary.
Which of the following is used to remove all elements of a dictionary?The clear dictionary python is used when the user wants to erase all the elements present inside a dictionary.
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