Update function in python

Python update() Function

The update() function in Python is used when we need to update the value of specified key of a specified dictionary. If specified key is not available, then a new item with given key and value will get inserted. For example:

x = "Day": "Sun", "Month": "Dec"> x.update("Day": "Mon">) print(x) x.update("Year": "2021">) print(x)

Python update() Function Syntax

The syntax of update() function in Python, is:

The iterable refers to a dictionary or an iterable of key-value pairs. The update() function does not returns any value. Therefore if you try to execute the following statement:

where x refers to a dictionary object, then the output will be None.

Python update() Function Example

Here is an example of update() function in Python. This program uses both dictionary and iterable (tuple) as iterable parameter while updating the dictionary:

x = 'Day': 'Sun'> print(x) a = 'Day': 'Mon', 'Date': '06'> x.update(a) print(x) x.update(Month='Dec', Year='2021') print(x)

Let’s create the last example of update() function. This program allows user to define the size of dictionary along with its all items:

x = dict() print("How many items to store in the dictionary: ", end="") noOfItem = int(input()) print("\nEnter", noOfItem, "Items.") for i in range(noOfItem): print("\nEnter the Key and Value for Item No.", i+1, ": ", sep="", end="") key = input() value = input() x.update() print("\nThe dictionary is:") print(x)

The snapshot given below shows the sample run, with user input 3 as number of items to insert in the dictionary, Name and Chloe as key and value of first item, Course and EECS as second item, University and MIT as third item:

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Python Dictionary update() Method

The update() method inserts the specified items to the dictionary.

The specified items can be a dictionary, or an iterable object with key value pairs.

Syntax

Parameter Values

Parameter	Description
iterable	A dictionary or an iterable object with key value pairs, that will be inserted to the dictionary

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Python’s Update Function: Understanding Its Purpose and Usage

Python3Output: Example 2: Using Set intersection_update() where there are no elements in common. Set intersection_update() operation on multiple sets.

Update value of a variable in a module

Within update() , there is a local variable named num that shadows the module’s num variable. By utilizing the global keyword and removing the local variable, you will be able to modify the value of the module’s num .

num = 0 def update(): global num num += 1 

Python Dictionary update() method, Python Dictionary update() method updates the dictionary with the elements from another dictionary object or from an iterable of key/value pairs

Python Dictionary update() Method

Full Tutorial: https://blog.finxter.com/python-dictionary-update-method/Email Academy: https Duration: 6:02

Python Tutorial — Dictionary Method

In this Python Programming video tutorial you will learn about the update method.Dictionaries
Duration: 6:05

Python Set – intersection_update() Method

The intersection_update() function in Python is employed to update a set by only retaining the common elements from all the sets that are given as arguments to the intersection_update() method.

Python set intersection_update() Method Syntax:

The following syntax can be used to update the intersection of multiple sets: set.intersection_update(set1, set2, set3, and so on up to set n).

To execute this task, it is necessary to have a minimum of two sets.

Python set intersection_update() Method Example:

Python3

A series of codes are listed below, with the first nine labeled as s1 through > . The next nine codes, labeled s2 through > , follow. Code s1.intersection_update(s2) is listed separately, followed by code # print updated s1 set . Finally, the last four codes are listed as print through , s1) .

After intersection_update, s1:

Example 1 : Set intersection_update() operation on multiple sets.

Python3

The following codes are listed: # declare set1 set1 = < "java" , "python" , "c/cpp" , "html" >Also included are: # declare set2 In addition, the following codes are present: set2 = < "php" , "html" , "java" , "R" >Moreover, the following codes are provided: # declare set3 Furthermore, you can find: set3 = < "java" , "python" , "ml" , "dl" >Additionally, the following codes are available: # declare set4 Furthermore, you can see: set4 = < "python" , "java" , "swift" , "R" >Also, you can find: # display sets In addition, the following codes are present: print ( «set1: <> set2: <> set3: <> set4: <> » . format (set1, set2, set3, set4)) Furthermore, you can find: Additionally, the following codes are provided: # perform intersection_update operation on set1 Moreover, you can see: set1.intersection_update(set2, set3, set4) Also, you can find: Finally, the following codes are listed: # display the result set print ( «After intersection_update, set1:» , set1)

set1: set2: set3: set4: After intersection_update, set1:

Example 2: Using Set intersection_update() where there are no elements in common.

Two distinct sets have been formed without any overlapping elements, resulting in an empty output.

Python3

# declare set1 set1 through > # declare set2 set2 through > # display sets print and (set1, set2) # perform intersection_update operation on # both the sets set and .intersection_update(set1, set2) # display the result set print and (set1)

Python dictionary update method, The .update() method is used for updating a dictionary using another dictionary, not for changing a single key/value pair.

Python dictionary update method

You actually want to do this:

for i, tag in enumerate(tag): tagDict[tag] = i 

The .update() function is designed to modify an entire dictionary with the use of another dictionary, rather than altering a single key/value pair.

tagDict.update(map(reversed, enumerate(tag))) 

Brian’s update reportedly improves the speed by approximately 5% compared to the iterative version. Gratitude to Brian for the update.

After being informed by saverio that my previous answer was incorrect, I have updated it. The solution provided by Torsten Marek, with some minor adjustments, is likely the most efficient and Pythonic approach.

tagDict.update((t, i) for (i,t) in enumerate(tag)) 

tagDict = dict((t, i) for i, t in enumerate(tag)) 

Python Set, Python update() function in set adds elements from a set (passed as an argument) to the set. Syntax : set1.update(set2).

Updating an instance of an object with the __init__ method

__init__ handles operations that do not involve memory references, in contrast to __new__ . The output of __new__ is a valid object that can be initialized by __init__ , and this object is what self refers to.

For the sake of clarity, you have the option to reverse the process.

class Person: def __init__(self, name: str, age: int): # Signal to whoever will read your code # that the class is supposed to have these attributes self.name = None self.age = None self.update(name=name, age=age) def update(self, name: str, age: int): self.name = name self.age = age 

Since there are no other methods calling __init__ , there is no risk of confusion.

If desired, you may refer to ForceBru’s response as well.

class Person: def __init__(self, name: str, age: int): self.name = name self.age = age def update(self, **attributes): for attribute, value in attributes.items(): if hasattr(self,attribute): setattr(self, attribute, value) else: raise AttributeError(f' has no attribute: ') x = Person(name='Henry',age=12) print(f'name=, age=') x.update(name='Joe') print(f'name=, age=') x.update(name='Kyle',age=20) print(f'name=, age=') 

name=Henry, age=12 name=Joe, age=12 name=Kyle, age=20 

This is a mere template and you may have other desired behaviors. For instance, you may not wish for users to overwrite attributes that begin with _ and so on.

ForceBru offers useful features such as linters and intellisense, therefore it’s recommended to choose the option that suits your needs.

Update value of a variable in a module, In update() , you’ve shadowed the module’s num variable with a local variable that’s also called num . If you get rid of it and use the

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Python Dictionary update()

The update() method updates the dictionary with the elements from another dictionary object or from an iterable of key/value pairs.

Example

marks = internal_marks = 
marks.update(internal_marks)
 print(marks) # Output:

Syntax of Dictionary update()

update() Parameters

The update() method takes either a dictionary or an iterable object of key/value pairs (generally tuples).

If update() is called without passing parameters, the dictionary remains unchanged.

Return Value from update()

update() method updates the dictionary with elements from a dictionary object or an iterable object of key/value pairs.

It doesn’t return any value (returns None ).

Example 1: Working of update()

d = d1 = # updates the value of key 2 
d.update(d1)
 print(d) d1 = # adds element with key 3 
d.update(d1)
 print(d)

Note: The update() method adds element(s) to the dictionary if the key is not in the dictionary. If the key is in the dictionary, it updates the key with the new value.

Example 2: update() When Tuple is Passed

dictionary = 
dictionary.update([('y', 3), ('z', 0)])
 print(dictionary)

Here, we have passed a list of tuples [(‘y’, 3), (‘z’, 0)] to the update() function. In this case, the first element of tuple is used as the key and the second element is used as the value.

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