Master Python variables and data types: a powerful tool for data manipulation

Variables are containers for storing data in python, and data types define the types of values ​​that can be stored in variables. Python Variables do not need to declare a type, but are inferred based on the assigned value.

Python data types

Python has a variety of built-in data types, including:

• Numeric types: int (integer), float (floating point number), complex (plural number)
• Sequence type: list (list), tuple (tuple), range (range)
• Mapping type: dict (dictionary)
• Set type: set (SET), frozenset (immutable set)
• Byte type: bytes (binary data)
• Text type: str(String), unicode(Unicode string)
• Boolean type: bool (Boolean value)
• Empty type: None

Data manipulation

Python provides a wide range of data manipulation operators and functions for manipulating data in variables:

Arithmetic operators:

• ,-,*,/,%: basic arithmetic operations
• **, //, %: powers, integer division and remainder

Comparison operators:

• ==, !=, <, >, <=, >=: Comparison of numerical values ​​and strings

Logical Operators:

• and, or, not: Boolean logical operations

Member operator:

• in, not in: Check whether the element is in the set or sequence

Assignment operator:

• =, =, -=, *=, /=: assignment and compound assignment

Type conversion

Python can use the built-in functions int(), float(), str(), etc. to convert data from one type to another:

x = 10
y = str(x)# 转换为字符串
print(type(y))# <class "str">

String operations

Python provides a wide range of functions and methods for string manipulation:

• connect:
• Slice: [start:end:step]
• Formatting: %, fORMat(), f-strings
• Find: find(), index(), rfind()

List operations

List is the most commonly used mutable sequence type in Python:

• Add: append(), extend()
• Delete: remove(), pop()
• Sort: sort(), reverse()
• Slice: [start:end:step]

Tuple operations

Tuples are immutable sequence types, similar to lists, but cannot be modified:

my_tuple = (1, 2, 3)
my_tuple[0] = 4# AttributeError: "tuple" object does not support item assignment

Dictionary operations

A dictionary is a mapping type in Python that maps keys to values:

• Add: my_dict[key] = value
• Get: my_dict[key]
• Delete: del my_dict[key]

Collection operations

A collection is an unordered collection data type, which does not contain duplicate elements:

• Add: my_set.add(element)
• Delete: my_set.remove(element)
• Intersection: my_set.intersection(other_set)

Selection of data structure

Choosing the right variable types and operations in Python is crucial. Think about the type of data in the variable, how it will be used, and the performance required.

• Numeric type: Used for mathematical calculations and comparisons.
• Sequence type: Used to store collections of ordered elements (such as lists and tuples).
• Mapping type: Used to store key-value pairs (such as dictionary).
• Set type: Used to store an unordered collection of unique elements.
• Boolean type: Used to represent true or false.
• Empty type: Used to indicate no value or unknown value.

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