Day 6 python learning Notes

A matching function parameters

When a certain number of parameters 1.1

Not necessarily the number of parameters 1.2

Defining a function, using the parameters tuples DETAILED front variable is incremented by *, such as:

 def func(*score):
    return sum(score)/len(score)

NOTE: The parameter tuple defined function, the call can not be used tuples can be added as required before tuples *, such as :

score=(1,2,3,4)

data=func(*score)

Note: You can also use the parameter dictionary table, use the tuple similar, slightly different specific manner, before the need to add a variable **, using as parameters the name defined dictionary, then you need to add * unpack

2 lambda expression

2.1 The basic format

lambda parameter 1, parameter 2 ...: Expression

2.2 lambda is an expression, you need to assign it to a variable to use

2.3 lambda expressions poor readability, use of a lambda expression is convenient nesting aspect, additional functions using fewer, and more easy way so that the expression

3 in the preparation of key-value pairs in the dictionary table value of the function name may be used, thereby simplifying the code

def hello_chinese(name):

    print(‘你好’,name)

def hello_english(name):

    print(‘hello’,name)

operation={‘c’:hello_chinese,’e’:hello_english}

while True:

    name=input(‘请输入姓名：’)

    if name == stop:

        break

    language=input(‘c=>中文 e=>英文’)

    (operation.get(language))(name)

4 function advanced tools

4.1 map function

The basic format:

map (function, iterables )

example:

def add(a):

    return a+5

l=list(range(1,6))

res=list(map(add,l))

4.2 filter function

The basic format:

Filter (function iterables )

example:

def jud(a):

    return a%2 == 0

l=list(range(1,8))

res=list(filter(jud,l))

Day 6 python learning Notes

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