Maximum of function python

max() Builtin Function

Python max() built-in function is used to find the maximum of a given iterable or, two or more arguments.

In this tutorial, you will learn the syntax of max() function, and then its usage with the help of example programs.

Syntax of max()

The syntax of max() function is

max(iterable, *[, key, default]) # or max(arg1, arg2, *args[, key])

Parameter	Description
iterable	An iterable like list, tuple, etc.
arg1, arg2, …	Values in which we have to find the maximum.
default	A default value, which will be returned if there are no items in the iterable.
key	[Optional] A key function based on whose return value the items in the iterable or the arguments are compared and the maximum is found.

Examples

1. Find maximum value in iterable

In this example, we will take a list of numbers and find the largest number in the list using max() function.

Python Program

a = [18, 52, 23, 41, 32] largest = max(a) print(f'Largest number in the list is : .')

rgest number in the list is : 52.

2. Find maximum of two or more numbers

In this example, we will take five numbers and find the largest number of these using max() function.

Python Program

largest = max(18, 52, 23, 41, 32) print(f'Largest number in the list is : .')

Largest number in the list is : 52.

3. max() with key function

In this example, we will take a list of numbers and find the number which leaves largest reminder when divided with 10, using max() function.

We will define a lambda function for key parameter that returns the reminder of the element in the list for comparison.

Python Program

a = [18, 52, 23, 41, 32] keyfunc = lambda x: x % 10 largest = max(a, key=keyfunc) print(f'Number that leaves largest reminder is : .')

Number that leaves largest reminder is : 18.

4. max() with default value

In this example, we will take an empty list and find the maximum number of the list using max() function. Since the list is empty, if we set default parameter for the max() function, the default value is returned.

Python Program

a = [] largest = max(a, default = 99) print(f'Largest number in the list is : .')

Largest number in the list is : 99.

Summary

In this tutorial of Python Examples, we learned the syntax of max() builtin function and how to use it, with the help of examples.

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Python Max Lambda [6 ways]

In this article, we have explained how to use lambda with max() built-in function in Python to find the maximum element in any iterable with custom objects. Additionally, we have presented how to implement max from scratch using lambda without using any built-in function.

Table of contents:

1. Creating Max function using Lambda (without built-in function)
2. max() built-in function in Python
3. Need of Lambda in max()
4. Using Lambda in max(): Examples
5. Concluding Note

Let us dive into Python Max Lambda with Python code examples along the way.

Creating Max function using Lambda (without built-in function)

In this section, we will use the lambda function to create an in-built maximum function that will find the maximum element between two elements.

Check the following Python code:

f = lambda a, b: a if a>b else b maximum = f(10, 14) print(maximum) 

In this, lambda takes 2 input numbers (a, b). The statement in lambda is a ternary operator which returns a if a is larger than b or else it returns b.

The output is as expected. The problem will be to take list as input and find the maximum element in it. The challenge is there can be only one statement in lambda and how can we iterate through a list in Python and keep track of the maximum element in one statement.

• return the first element of the list if the length of the list is 1. If there is only one element, it is the largest element.
• If length of list is greater than 1, then use this lambda recursively.
• Compare the first element l[0] with the maximum element of the rest of the list that is fetched by recursively calling the lambda on l[1:].
• This allows us to fetch the maximum element of a list.

f = lambda l: l[0] if len(l) == 1 else l[0] if l[0] > f(l[1:]) else f(l[1:]) list = [19, 7, 17, 97, 5] maximum = f(list) print(maximum) 

The output is as expected.

Another alternative will be to use the reduce function in lambda to find the maximum element:

from functools import reduce list = [19, 7, 17, 97, 5] maximum = reduce(lambda x, y: x if x >= y else y, list) print(maximum) 

The output is as expected.

This demonstrates how we can write our own lambda to find the maximum element without using the max() in-built function.

max() built-in function in Python

Following is the syntax of the built-in max function in Python:

• Iterable: This is a list of objects whose max we need. This can be any iterable object in Python.
• Key: This is optional and can be used to control how elements in the list are compared to find the maximum element.
• The function returns an object from the iterable that is maximum.

Key can take 5 different things in Python:

• Built in function
• User defined function
• Lambda function / Anonymous function
• Itemgetter
• Attrgetter

In this article at OpenGenus, we have focused on how to use Lambda in Key attribute of max() to find the maximum element of any list in desired way.

Using lambda in max() brings all benefits of lambda along with keep the code short and clear compared to other alternatives like User defined function.

Following is an example of using max() without key attribute:

list = [19, 7, 17, 97, 5] maximum = max(list) print(maximum) 

It works as expected but this is not the case always. We will see in the next section.

Need of Lambda in max()

Let us consider the case such that the list has numbers but as strings. If we use max function on it, max() will compare the elements as string and not as numbers and hence, the result will not be as expected.

Consider the following Python code using max() in-built function:

list = ["19", "7", "17", "29", "5"] maximum = max(list) print(maximum) 

We will expect the answer to be 29 as we are considering the data as numbers. As the data is a list of string, max() will return 7.

The fix in this case is to use the key attribute in max() function to control how the elements are compared. We can use the lambda function for key attribute of max() function.

The code using lambda will be as follows:

list = ["19", "7", "17", "29", "5"] maximum = max(list, key=lambda x:int(x)) print(maximum) 

In this case, the lambda function is converting each element to its corresponding integer value using the int() in-built function in Python.

Using Lambda in max(): Examples

In this previous section, we saw a specific use case of lambda in the max() in-built function. There are several ways lambda can be used in max() such as:

• If elements in list are in string format but you want to compare them as integers, use lambda to convert each element to its corresponding integer value using int() as part of the key attribute of max().

maximum = max(list, key=lambda x:int(x)) 

• If there is a list of tuples and you want to find the maximum element based on the second element of the tuple, we can use lambda as follows:

list = [(1,'aditya'), (2,'ue'), (9,'ben'), (5,'ned')] max(list, key = lambda x: x[1]) 

• Find maximum element in a list that has a mixture of string and integers by comparing string by converting into integer. By default, max() in-built function will give error in Python3 if applied on this list but on passing the correct lambda in key attribute it will work as expected.

list = ['1', '9', 100, 2] max(list, key=lambda x: int(x)) 

• Similarly, you can use lambda in the key attribute of max() in-built function to support any custom object in Python.

Concluding Note

With this article at OpenGenus, you must have the complete idea of how to use lambda to find the maximum element and how to use lambda in the key attribute of max() in-built function in Python.

Lambda is a very feature in Python. Use it to find maximum element in any custom way.

Ned Nedialkov

Professor of Computing at McMaster University | Ph.D in Computer Science from University of Toronto in 1999 | Native of Bulgaria | Research in Scientific Computing

OpenGenus Tech Review Team

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Python Max () – Примеры

Функция Python Max () используется для нахождения максимума заданного потенциала или двух или более аргументов.

Мы можем предоставить либо имеющуюся итеративное; или два или более предметов в качестве аргументов к функции max (), но не смешивают, и другие элементы.

Необязательно, мы также можем дать названный ключ Функция, основанная на величине возврата которых элементы в по сравнению с намерением или аргументам, а максимум найден.

Синтаксис – max ()

max(iterable, *[, key, default]) # or max(arg1, arg2, *args[, key])

Мы также можем предоставить значение по умолчанию, которое будет возвращено, если в неразрешении нет элементов.

Пример 1: Найти максимум с намерением

В этом примере мы возьмем список номеров и нахожу наибольшее количество в списке, используя функцию max ().

a = [18, 52, 23, 41, 32] largest = max(a) print(f'Largest number in the list is : .')

rgest number in the list is : 52.

Пример 2: Найти максимум двух или более предметов

В этом примере мы возьмем пять чисел и нахожу наибольшее количество этих с использованием функции MAX ().

largest = max(18, 52, 23, 41, 32) print(f'Largest number in the list is : .')

Largest number in the list is : 52.

Пример 3: max () с функцией ключа

В этом примере мы возьмем список чисел и нахожу номер, который оставляет наибольшее напоминание, когда разделено на 10, используя функцию max ().

Мы определим функцию лямбда для ключ Параметр, который возвращает напоминание о элементе в списке для сравнения.

a = [18, 52, 23, 41, 32] keyfunc = lambda x: x % 10 largest = max(a, key=keyfunc) print(f'Number that leaves largest reminder is : .')

Number that leaves largest reminder is : 18.

Пример 4: max () с значением по умолчанию

В этом примере мы возьмем пустой список и нахожу максимальное количество списка, используя функцию max (). Поскольку список пуст, если мы установим параметр по умолчанию для функции MAX (), возвращается значение по умолчанию.

a = [] largest = max(a, default = 99) print(f'Largest number in the list is : .')

Largest number in the list is : 99.

Резюме

В этом руководстве примеров Python мы изучили синтаксис MAX () встроенной функции и как его использовать, с помощью примеров.

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max(arg1, arg2, *args, key=None)

Возвращает элемент с набольшим значением из переданных в функцию.

Параметры ¶

• args : Если указано несколько позиционных аргументов, элемент с наибольшим значением разыскивается среди них.
• iterable — итерируемый объект, такой как список, кортеж, набор, словарь и т. д. Если указан один позиционный аргумент, то ожидается, что он является итерируемым объектом. Возвращается элемент с максимальным значением, найденный среди элементов этого объекта.
• *iterables (необязательно) — любое количество итераций; может быть более одного
• key (необязательно) — ключевая функция, в которую передаются итерации, а сравнение выполняется на основе возвращаемого значения.
• default (необязательно) — Этим аргументом можно указать значение, которое следует вернуть, если итерируемый объект окажется пустым. Если последовательность пуста и аргумент не указан, возбуждается ValueError .

Возвращаемое значение ¶

• max() в указанном итерируемом объекте, или среди аргументов, обнаруживает и возвращает элемент с набольшим значением.

Примеры ¶

number = [3, 2, 6, 5, 9, 8]
largest_number = max(number);
 
print("Самое большое число:", largest_number)
 
# Результат: 
Самое большое число: 9

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