Python Generator Delete Dict Key

  1. Python Dict Get Keys
  2. Python Generator Delete Dict Keyboard
  3. Delete Multiple Keys From Dictionary Python
  4. How To Delete In Dict Python
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Python Generator Delete Dict Key

To delete a key regardless of whether it is in the dictionary, use the two-argument form of dict.pop. Mydict.pop('key', None) This will return mydictkey if key exists in the dictionary, and None otherwise. To delete a key regardless of whether it is in the dictionary, use the two-argument form of dict.pop: mydict.pop('key', None) This will return mydictkey if key exists in the dictionary, and None otherwise. If the second parameter is not specified (ie. Mydict.pop('key')) and key does not exist, a KeyError is raised. Python dictionary method haskey returns true if a given key is available in the dictionary, otherwise it returns a false. Following is the syntax for haskey method − dict.haskey(key) Parameters. Key − This is the Key to be searched in the dictionary. Return Value.

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Each key is separated from its value by a colon (:), the items are separated by commas, and the whole thing is enclosed in curly braces. An empty dictionary without any items is written with just two curly braces, like this: {}.

Keys are unique within a dictionary while values may not be. The values of a dictionary can be of any type, but the keys must be of an immutable data type such as strings, numbers, or tuples.

Accessing Values in Dictionary

To access dictionary elements, you can use the familiar square brackets along with the key to obtain its value. Following is a simple example −

When the above code is executed, it produces the following result −

If we attempt to access a data item with a key, which is not a part of the dictionary, we get an error as follows −

When the above code is executed, it produces the following result −

Updating Dictionary

Python Dict Get Keys

You can update a dictionary by adding a new entry or a key-value pair, modifying an existing entry, or deleting an existing entry as shown in a simple example given below.

When the above code is executed, it produces the following result −

Delete Dictionary Elements

You can either remove individual dictionary elements or clear the entire contents of a dictionary. You can also delete entire dictionary in a single operation.

To explicitly remove an entire dictionary, just use the del statement. Following is a simple example −

Python Generator Delete Dict Key

This produces the following result.

An exception is raised because after del dict, the dictionary does not exist anymore.

Note − The del() method is discussed in subsequent section.

Properties of Dictionary Keys

Dictionary values have no restrictions. They can be any arbitrary Python object, either standard objects or user-defined objects. However, same is not true for the keys.

There are two important points to remember about dictionary keys −

Python Generator Delete Dict Keyboard

(a) More than one entry per key is not allowed. This means no duplicate key is allowed. When duplicate keys are encountered during assignment, the last assignment wins. For example −

When the above code is executed, it produces the following result −

(b) Keys must be immutable. This means you can use strings, numbers or tuples as dictionary keys but something like ['key'] is not allowed. Following is a simple example −

When the above code is executed, it produces the following result −

Built-in Dictionary Functions and Methods

Python includes the following dictionary functions −

Sr.No.Function & Description
1cmp(dict1, dict2)

No longer available in Python 3.

2len(dict)

Gives the total length of the dictionary. This would be equal to the number of items in the dictionary.

3str(dict)

Produces a printable string representation of a dictionary

4type(variable)

Returns the type of the passed variable. If passed variable is dictionary, then it would return a dictionary type.

Delete Multiple Keys From Dictionary Python

Python includes the following dictionary methods −

How To Delete In Dict Python

Sr.No.Method & Description
1dict.clear()

Removes all elements of dictionary dict

2dict.copy()

Returns a shallow copy of dictionary dict

3dict.fromkeys()

Create a new dictionary with keys from seq and values set to value.

4dict.get(key, default=None)

For key key, returns value or default if key not in dictionary

5dict.has_key(key)

Removed, use the in operation instead.

6dict.items()

Returns a list of dict's (key, value) tuple pairs

7dict.keys()

Returns list of dictionary dict's keys

8dict.setdefault(key, default = None)

Similar to get(), but will set dict[key] = default if key is not already in dict

9dict.update(dict2)

Adds dictionary dict2's key-values pairs to dict

10dict.values()

Returns list of dictionary dict's values