Python Learning note 010--anonymous function lambda

1 syntax

Lambda arg1, arg2:arg1 + arg2 + 1

Arg1, arg2: Parameters

Arg1 + arg2 + 1: expression

2 description

The anonymous function does not need a return value, and the expression itself results in a return value.

Lambda is simply code-less and does not improve program performance

If you can use for ... in ... if To complete, it is best not to use the anonymous function lambda

When using lambda, the function does not include loops, nesting, or, if it does exist, it is best to use the DEF function, which makes the code more readable and reusable

Lambda is used to write simple functions, and DEF is used to handle more powerful tasks.

3 Example 3.1 anonymous function with no parameters

Lambda:5>>> a<function <lambda> at 0x7f20f53be2f0>>>>  A ()

3.2 Anonymous functions for single parameters

Lambda x:x+1print(A (2))

Run: 3

3.3 Anonymous functions with multiple parameters

Lambda x, y:x + y + 1print(A ())print(A (y=3,x=2))

Run:

46

3.4 Other

1 Lambda x:x+1 (1)2 <function <lambda> at 0x7f20f4cfb9d8>

Some blogs say that the first line of input can directly get the result, in fact, only get the address of the anonymous function (hex)

Lambda x:x+1 (1)<function <lambda> at 0x7f20f4cfb9d8>>>> ID (  Lambda x:x+1 (1))139779554729768>>> hex (ID (lambda x:x+1 (1)))'  0x7f20f4cfb9d8'

If the function value needs to be obtained, the

>>> (Lambda x:x+1) (1)2

Same

Print (Lambda x:x+1 (1))    # <function <lambda> at 0x7fa097b54f28> Print (Lambda x:x+1) (1))   # 2

Calculation

( lambda x: ( Lambda y: (lambda z:x + y + z) (1)) (2)) (3)

equals how much? 6

Refer to Python's anonymous function lambda interpretation and usage, Python learning Note (12): lambda expression and functional programming, Python lambda introduction

Python Learning note 010--anonymous function lambda