Python Basic content Four

Null string, empty list bool type is False

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Content:

Simplified function definition, lambda

function definition:

Method One:

def func (ARG):

Return arg+1

Method Two:

Func = lambda Arg:arg + 1

Lambda Features:

1, for the simple logic

2. Auto return

Built-in functions:

First, the Map method

Iterate through the sequence, manipulate each element in the sequence, and finally get a new sequence

Second, the filter method

Filter, only if the value is true, you can, otherwise filter out

Cases:

Li = [11,22,33,44,55]

Print (Filter (lambda a:a > 33,li))

Results: [44, 55]

Third, reduce

For all elements within a sequence, there is an initial value that accumulates on top of this initial value.

Cases:

Li = [11,22,33,44,55]

Print reduce (lambda a1,a2:a1+a2,li,1000)

Results: 1165

Map: All element operations

Filter: Gets the specified element action collection

Reduce: additive operation

Yield generator:

Remember the last action, and the next time you execute it, continue

Return life cycle is over

For example:

def func (ARG):

Seed = 0

While True:

Seed = seed + 1

If seed > ARG:

Return directly ends the life cycle of the function

Else

Yield seed temporarily freezes the life cycle of a function

For I in Func (10):

Print (i)

Python Basic content Four