Условие с boolean python

Статья Python3 6.Boolean,Инструкция If

Python содержит класс «bool» который используется для выражения условной логики в коде. Класс «bool» возвращает два значения «True» или «False» (истина или ложь), любое не пустое и не нулевое значение является (True), ноль или пустой объект равняется (False).
Возможность добавлять целые числа в списке которые больше определенного значения в другой список.
Выводить из списка только строковые\целые\дробные значения.
Сравнение двух переменных и использование их неравенства\равенства и тд как условие для последующего кода
Для операции поместите оператор «bool» между переменными, сравнивать возможно целые числа\дробные\строки\списки , а так же присвоить результат сравнения переменной

«==» если значения равны возвращает «True», иначе «False»

>>> ["one", "two", "three", "four"] == ["one", "two", "three", "four"] True

>>> ["one", "two", "three"] == ["one", "two", "three", "four"] False

>>> list_one = [1, 2, 3, 4, 5] >>> list_two = [1, 2, 3, 4, 5, 6] >>> len(list_one) == len(list_two) False

>>> int_list = [1, 2, 3, 4, 5] >>> int_list[0] < int_list[4] True

>>> int_list[0] > int_list[4] False

Python содержит инструкцию if которая позволяет реализовать логическое ветвление.
Состоит инструкция из обязательной части if и двух необязательных elif и esle.
Часть if проверяет условие , если условие истинно то выполняется вложенный блок части if иначе часть if пропускается.
Далее следует необязательная часть elif , если условие части if ложно, но истинно для части elif то выполняется вложенный блок части elif иначе часть elif пропускается
Последней следует необязательная часть else которая не содержит условия , выполняется если условия частей if и elif были ложны

if (условие1): # двоеточие обязательно Вложенный блок части if # отступ в 4 пробела или 1 табуляция elif(условие 2\альтернативное условие): Вложенный блок части elif # отступ в 4 пробела или 1 табуляция else: (без условия) Вложенный блок части else # отступ в 4 пробела или 1 табуляция

if 1: # так как единица всегда True print("True")

x = 2 if x == 1: print("True") else: print("False")

x = 3 y = 4 if x > y: print(x, "больше", y) elif x < y: print(x, "меньше", y)

player_charm = 6 min_charm = 5 charm_need = 15 if player_charm >= charm_need: print("Вам удалось уговорить НПС") elif charm_need > player_charm >= min_charm: print("Вы узнали некоторые сведения") else: print("Попытка не удалась")

Как это работает:
Переменной player_charm присвоено значение 6 , если переменная player_charm больше или равна переменной charm_need то выполняется вложенный блок части if , если переменная player_charm меньше переменной charm_need то вложенный блок части if пропускается.
Если же переменная player_charm меньше переменной charm_need но при этом больше переменной или равна min_charm то выполняется вложенный блок части elif
Если обе части if/elif были пропущены , выполняется вложенный блок части else

Инструкция if для цикла for
Использование инструкции if для нахождения определенного элемента в списке, присвоение элемента переменной и вывод функцией print()

str_list = ["one", "two", "three", "four", "five"] for value in str_list: if value == "four": element = value print(element) 'four'

str_list = ["one", "two", "three", "four", "five"] counter = 0 # счетчик index = 0 for valie in str_list: if value == "four": index = counter counter += 1 # если итерация прошла а условие не было выполнено # счетчик + 1 print(index)

Определение какой элемент в списке целых чисел больше или меньше указанного в условии и сортировка их по спискам согласно условию

int_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] greater_5 = [] lower_5 = [] for value in int_list: if value > 5: greater_5.append(value) elif value < 5: lower_5.append(value) else: five = value print(greater_5) print(lower_5) print(five)

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Python Boolean and Conditional Programming: if.. else

Besides numbers and strings, Python has several other types of data. One of them is the Boolean data type. Booleans are extremely simple: they are either true or false. Booleans, in combination with Boolean operators, make it possible to create conditional programs: programs that decide to do different things, based on certain conditions.

The Boolean data type was named after George Boole, the man that defined an algebraic system of logic in the mid 19th century.

What is a Boolean?

Let’s start with a definition:

Boolean A boolean is the simplest data type; it’s either True or False .

In computer science, booleans are used a lot. This has to do with how computers work internally. Many operations inside a computer come down to a simple “true or false.” It’s important to note, that in Python a Boolean value starts with an upper-case letter: True or False . This is in contrast to most other programming languages, where lower-case is the norm.

In Python, we use booleans in combination with conditional statements to control the flow of a program:

>>> door_is_locked = True >>> if door_is_locked: . print("Mum, open the door!") . Mum, open the door! >>>_

Here’s an interactive version of the same code that you can experiment with:

First, we define a variable called door_is_locked and set it to True . Next, you’ll find an if-statement. This is a so-called conditional statement. It is followed by an expression that can evaluate to either True or False . If the expression evaluates to True , the block of code that follows is executed. If it evaluates to False , it is skipped. Go ahead and change door_is_locked to False to see what happens.

An if can be followed by an optional else block. This block is executed only when the expression evaluates to False . This way, you can run code for both options. Let’s try this:

>>> door_is_locked = False >>> if door_is_locked: . print("Mum, open the door!") . else: . print("Let's go inside") . Let's go inside >>>_

Thanks to our else-block, we can now print an alternative text if door_is_locked is False . As an exercise, try to modify the interactive code example above to get the same result.

Python operators

The ability to use conditions is what makes computers tick; they make your software smart and allow it to change its behavior based on external input. We’ve used True directly so far, but more expressions evaluate to either True or False . These expressions often include a so-called operator.

There are multiple types of operators, and for now, we’ll only look at these:

Comparison operators

Let’s look at comparison operators first. You can play around with them in the REPL:

>>> 2 > 1 True >>> 2 < 1 False >>> 2 < 3 < 4 < 5 < 6 True >>> 2 < 3 >2 True >>> 3 >> 3 >= 2 True >>> 2 == 2 True >>> 4 != 5 True >>> 'a' == 'a' True >>> 'a' > 'b' False

This is what all the comparison operators are called:

Operator	Meaning
>	greater than
	smaller than
>=	greater than or equal to
	smaller than or equal to
==	is equal
!=	is not equal

Python’s boolean operators

As can be seen in the examples, these operators work on strings too. Strings are compared in the order of the alphabet, with these added rules:

You’re probably wondering what the logic is behind these rules. Internally, each character has a number in a table. The position in this table determines the order. It’s as simple as that. See Unicode on Wikipedia to learn more about it if you’re interested.

Logical operators

Next up: logical operators. These operators only work on booleans and are used to implement logic. The following table lists and describes them:

Operator	What is does	Examples
and	True if both statements are true	True and False == False False and False == False True and True == True
or	True if one of the statements is true	True or False == True True or True == True False or False == False
not	Negates the statement that follows	not True == False not False == True

Python logical operators

Here are some examples in the REPL to help you play around with these:

>>> not True False >>> not False True >>> True and True True >>> True and False False

Comparing different types in Python

When you try to compare different types, you’ll often get an error. Let’s say you want to compare an integer with a string:

This is how Python tells you it can’t compare integers to strings. But there are types that can mix and match. I would recommend against it because it makes your code hard to understand, but for sake of demonstration, let’s compare a boolean and an int:

>>> True == 1 True >>> False == 0 True >>> True + True 2 >>> False + False 0 >>> False + True 1 >>> True + 3 4 >>>

As can be seen, True has a value of 1, and False has a value of 0. This has to do with the internal representation of booleans in Python: they are a special kind of number in Python.

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Условие с boolean python

Last updated: Feb 20, 2023
Reading time · 3 min

# Using booleans in an if statement in Python

Use the is operator to check for a boolean value in an if statement, e.g. if variable is True: .

The is operator will return True if the condition is met and False otherwise.

Copied! 
variable = True # ✅ check if a variable has a boolean value of True if variable is True: # 👇️ this runs print('The boolean is True') # ------------------------------------------ # ✅ check if a variable is truthy if variable: # 👇️ this runs print('The variable stores a truthy value') 

The first example checks if the variable stores a True boolean value.

You should use the is operator when you need to check if a variable stores a boolean value or None .

Use the equality operators (equals == and not equals != ) when you need to check if a value is equal to another value, e.g. 'abc' == 'abc' .

In short, use the is operator with built-in constants like True , False and None .

# Checking for False or a Falsy value

You can use the same approach when checking for False or a falsy value in an if statement.

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variable = False if variable is False: # 👇️ this runs print('The boolean is False') if not variable: # 👇️ this runs print('The variable stores a falsy value') 

Note that checking for the boolean values True and False is very different than checking for a truthy or falsy value.

# Checking for a Truthy Value in an if statement

Here is how we would check for a truthy value in an if statement.

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variable = True if variable: # 👇️ this runs print('The variable stores a truthy value') 

The falsy values in Python are:

• constants defined to be falsy: None and False .
• 0 (zero) of any numeric type
• empty sequences and collections: "" (empty string), () (empty tuple), [] (empty list), <> (empty dictionary), set() (empty set), range(0) (empty range).

Copied! 
if 'hello': print('this runs ✅') if ['a', 'b']: print('This runs ✅') if '': print('this does NOT run ⛔️') if 0: print('this does NOT run ⛔️') 

if not X returns the negation of if X . So with if not X , we check if X stores a falsy value.

You will often have to use multiple conditions in a single if statement.

You can do that by using the boolean AND or boolean OR operators.

Copied! 
if True and True: print('This runs ✅') if True and False: print('This does NOT run ⛔️') # -------------------------------------- if True or False: print('This runs ✅') if False or False: print('This does NOT run ⛔️') 

The first two examples use the boolean AND operator and the second two examples use the boolean or operator.

When using the boolean and operator, the expressions on the left and right-hand sides have to be truthy for the if block to run.

In other words, both conditions have to be met for the if block to run.

Copied! 
if True and True: print('This runs ✅') if True and False: print('This does NOT run ⛔️') 

When using the boolean or operator, either of the conditions has to be met for the if block to run.

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if True or False: print('This runs ✅') if False or False: print('This does NOT run ⛔️') 

If the expression on the left or right-hand side evaluates to a truthy value, the if block runs.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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