accordance with the conditions of use, lambda expression;Although it looks neat, you can define a function without running a single thing. Note that this code, can read, if you read more laborious, this is not the result of Python, not all use lambda expression, can also use the list expression,They all operate on a sequence;List expression notationlambda->List-
one, anonymous function lambdaLambda argument1,argument2,... argumentn:expression using arguments1, Lambda is an expression, not a statement.Because of this, Lambda can appear where the DEF is not allowed in the Python syntax---for example, in a list constant or in a parameter called by a function, and as an expression
A Brief Introduction to lambda expressions and pythonlambda expressions in python
Recently, coding found that using lambda still has many advantages. In many cases, the code is more neat and pythonic, so here is a brief summary.
1. What is lambda?
A simple example:
func =
This article mainly records my understanding of several advanced syntax concepts: Anonymous functions, lambda expressions, closures, and decorators. These concepts are not specific to Python, but this article only describes them using Python. 1. anonymous functions
Anonymous function is a function that is not bound to any identifier. it is used in the functional
Reviewing Python today and seeing an example of a lambda function, using lambda in Python is handy at some point because you don't have to create a new function to implement some simple functionality. But there is a lambda instanc
), range (8))[0, 2, 4, 6, 8, 10, 12, 14]reduce (function, sequence, starting_value): Calls the function in the order of the item in the sequence, and if there is a starting_value, it can also be called as an initial value. For example, you can use the sum of a list:>>> def add (x, y): return x + y>>> reduce (Add, range (1, 11))55 (Note: 1+2+3+4+5+6+7+8+9+10)>>> reduce (Add, range (1, 11), 20)75 (Note: 1+2+3+4+5+6+7+8+9+10+20)
Common methods for modules and modules
Function-Type programming
Yield
Ternary operations
Lambda expression
Built-in Culvert number
Common modules
"Common methods for modules and modules"The critical __init__.py #包一定要有这个__init__. py file, he is the package, in order to use the form Package name Import module name (. py file name) to refer to a module of this package function functionDetermine if the main file: __name__if _
Python: high-order functions and lambda expressions, pythonlambda
Reason:
The python syntax is simple at a glance, but it is used in NLP. I think it is a bit easy to understand because it is less practical.
Read the source code of youtube_dl and see the usage of the filter () function and the lambda expression in it. I
Python Lambda functions and sorting, and pythonlambda
Lambda functions are the smallest function that quickly defines a single row. They are borrowed from Lisp and can be used wherever functions are needed. The following example compares the definition of a traditional function with a
, 12, 14] reduce (function, sequence, starting_value): calls the function sequentially for the items in sequence, if starting_value exists, it can also be called as an initial value. For example, it can be used to sum the List: >>> def add (x, y): return x + y >>> reduce (add, range (1, 11) 55 (Note: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) >>> reduce (add, range (1, 11), 20) 75 (Note: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 20)
Lambda
Lambda is used to compile simple functions.
Lambda is used as follows: lambda arg1, arg2, arg3,..., argn: expression
Fs = [(lambda n, I = I: I + n) for I in range (10)]>>> Fs [3] (4)7>>> Fs [4] (4)8>>> Fs [5] (4)9
Filter
Filter, map, and reduce are all
Use Lambda in Python to create anonymous functions. Lambda comes from the lisp language. The Lambda format is as follows:
Lambda arg1, arg2....: Lambda creates a function object, but does not assign this function object to an iden
;> round (1.12, 1)
1.1
>>> round (1.123, 2)
1.12
The first argument is a floating-point number, and the second argument is a reserved scale, optional, and left to an integer by default if not written.If there is a requirement for precision after interception, join the following link:
A little pit in Python about the round functionWhy does Python not solve rounded (round) "Bugs"?
Data Filtering (filter)
Use
anonymous function lambdaLambda Argument1,argument2,... argumentn:expression using arguments1, Lambda is an expression, not a statement.Because of this, lambda can appear where the DEF is not allowed in the Python syntax---for example, in a list constant or in the parameters of a function call.2. The body of a
Several advanced syntax concepts of Python (lambda expression closure decorator), pythonlambda
1. Anonymous FunctionsAnonymous function is a function that is not bound to any identifier. It is used in the functional programming ages field. Typical applications:1) passed as a parameter to the high-order function (higher-order function). For example, the built-in f
function itselfprint>>> pinprint># The function itself can be assigned to a variable, and the variable can point to the function We call this print function with a variable to verify the result as follows>>> p ("check") CheckSummary: The function name is also a variable, for the built-in function of print (), it is entirely possible to think of the function name print as a variable, which points to an object that can print anything.Note: The actual program code must not be written like this, ju
, 6, 8, 10, 12, 14]
Reduce (function, sequence, starting_value): Calls the function sequentially for items in sequence. If starting_value exists, it can also be called as an initial value. For example, it can be used to sum the list:>>> Def add (x, y): Return x + y>>> Reduce (ADD, range (1, 11 ))55 (Note: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)>>> Reduce (ADD, range (1, 11), 20)75 (Note: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 20)
Tag: Port uses code to simplify toolbar BSP LTE list andIn the process of learning Python, Lambda's syntax often appears, and now it's sorted out for later viewing.1. What is lambda?Here's an example:1 func=lambda x:x+12 Print (func (1)) 3 #24 Print (func (2)) 5 #36 7 #以上lambda
supports the corresponding number of parameter inputs:
The code is as follows:
>>> Def add (x, y): return x + y>>> Map (add, range (8), range (8 ))[0, 2, 4, 6, 8, 10, 12, 14]
Reduce (function, sequence, starting_value ):Call the function sequentially for items in sequence. if starting_value exists, it can also be called as an initial value. for example, it can be used to sum the List:
The code is as follows:
>>> Def add (x, y): return x + y>>> Re
There are also differences between Python def and Python lambda. Let's share your experiences today.Let's talk about two similarities: these two very important similarities are that they can both define some fixed methods or processes to provideProgramFor example, we want to define a variable plus 2.First, look at
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