table of Contents
I. Overview of functions
- Understanding and definition of the function
- Use and function of the calling process
- Parameter transfer function
- Function's return value
- Local and global variables
- letter lambda
II. Understanding and function definition
Every day
Code:
def dayUp(df):
dayup = 1
for i in range(365):
if i % 7 in [6, 0]:
dayup = dayup * (1 - 0.01)
else:
dayup = dayup * (1 + df)
return dayup
dayfactor = 0.01
while dayUp(dayfactor) < 37.78:
dayfactor += 0.001
print("工作日的努力参数是：{:.3f} ".format(dayfactor))effect:
2.1 Definition of functions
Function is a piece of code
- Function is a piece having a specific function, reusable statement group
- Abstract function is one function, the specific function is generally expressed as a function
- Two effects: reduce the difficulty of programming and code reuse
def <函数名>(<参数(0个或多个)>) :
<函数体>
return <返回值>y = f(x)
- When the function definition, the specified parameter is a placeholder
- After the function definition, if not through the call, will not be executed
- When the function definition, the parameter is input, processing body is a function, the result is output (IPO)
III. Function calls and use
3.1 function calls
Call function code is run
def fact(n): # 函数的定义
s = 1
for i in range(1,n+1):
s *= i
return s
fact(10) # 函数的调用- When call to be given actual parameters
- Alternatively actual parameters defined in the parameter
- After the function call to get the return value
3.2 function calls the process
Function can have arguments, or may not, but must retain the brackets
def <函数名>(<非可选参数>，<可选参数>) :
<函数体>
return <返回值>- Examples of a (general call):
Code:
def get_pi(num):
import random
count = 0
for i in range(num):
x, y = random.random(), random.random()
dist = pow((x - 0) ** 2 + (y - 0) ** 2, 0.5)
if dist < 1:
count += 1
print(4 * count / num)
get_pi(10)
get_pi(100)
get_pi(1000)
get_pi(10000)
get_pi(100000)effect:
- Examples of bis (return value):
Code:
def add_sum(num):
count = 0
for i in range(1, num):
count += i
return count
res1= add_sum(101)
print('res1:',res1)
res2 = add_sum(1001)
print('res2:',res2)
res3 = add_sum(10001)
print('res3:',res3)effect:
IV. Set type
4.1 deduplication
Code:
# 大括号内用逗号隔开多个元素,集合(哈希表)是无序的,去重
s1 = {'nick', 'handsome', 'wuhao', 'dsb', 1231, 1.0, 1.0, 1.0, 'dsb', 'dsb'}
print(s1)effect:
4.2 be installed for the collection of sequences
s2 = set('nick')
s3 = set(['1', 2, 3])
print(s2)
print(s3)effect:
4.3 built-in method of collection
Code:
s1 = {'luowenxiang', 'handsome', 'hanye', 'beautiful'}
s2 = {'luowenxiang', 'handsome', 'hanye', 'beautiful','0.0','haha'}
s3 = {'520','1314'}
s1.add('5201314')
s2.remove('0.0')
print(s1)
print(s2)
s2.discard('haha')
print(s2)
s3.clear()
print(s3)
s4 = s1.copy()
print(s4)
effect:
V. sequence
5.1 Types of defined sequence
Sequence is a set of elements has a relationship with a
- Sequence is the one-dimensional vector elements, it may be different types of elements
- Similar mathematical sequence of elements: 0,1,2,3,4,5,6,7,8,9
- Between elements guided by the number, sequence specific elements accessed by subscripts 0, 1, ......
5.2 Sequence handler and method
Code:
name = 'luowenxiang'
#0123456789...
name2 = name[6:] #切片 从第七个元素开始输出到最后一个元素
name3 = name[0] #索引 输出第一个元素
name4 = name2 + name3 #s + t 连接两个序列s和t
name5 = name*5 # sn 或 ns 将序列s复制n次
print('len(name):',len(name)) # 长度
print('l' in name) # x in s 如果x是序列s的元素，返回True，否则返回False
print('l' not in name) # x not in s 如果x是序列s的元素，返回False，否则返回True
print(name2)
print(name3)
print(name4)
print(name5)
effect:
VI. The basic statistic calculation
6.1 Analysis
Basic statistics
- Requirements: given a set of numbers, they have a summary of understanding
- how should I do it?
The total number, sum, average, variance, median ...
- Total number: len ()
- Sum: for ... in
- Average: sum / total number
- Variance: each data and the difference between the average and the average of the square
- Median: Sort, and then ...
- Get an intermediate odd, even-averaged to find the middle of two
6.2 examples to explain
A set of data input by the user (a user input), data and calculates the median / average / variance / summation
Code:
# 通过用户输入一组数据(用户一个一个输入),然后计算数据的中位数/平均值/方差/求和
#输入数据
nums = []
while True:
num1 = input('请输入你需要输入的数字(输入 q 退出):')
if num1 == 'q':
break
nums.append(int(num1))
#定义中位数
def get_median(nums):
nums.sort()
nums_len = len(nums)
if nums_len % 2 == 0:
print((nums[int(nums_len / 2 - 1)] + nums[int(nums_len / 2)]) / 2)
else:
print(nums[nums_len // 2])
median = get_median(nums) #输出中间数
#定义求和
def get_sum(nums): # ['123', '123', '213', '234', '98234']
count = 0
for i in nums:
count += int(i)
return count
count = get_sum(nums)
print('count:',count) #输出求和数据
#定义平均数
def get_average(nums):
count = get_sum(nums)
average_count = count/len(nums)
return average_count
average_count = get_average(nums)
print('average_count:',average_count) #输出平均数
#定义方差
def get_variance(nums):
average_count = get_average(nums)
variance_count = 0
for i in nums:
variance_count += pow(i-average_count,2)
return variance_count
variance_count = get_variance(nums)
print('variance_count:',variance_count) #输出方差
effect:
VII. Dictionary
Creation and output 7.1 dictionary
Code:
dic1 = {'name':'lwx','lover':'hanye','time':'forever'}
#'键' ：'值' #创建一个字典
print(dic1) #输出字典
print(dic1['name']) #输出键：name中的值
print(dic1['lover']) #输出键：lover中的值
print(dic1.get('time')) #输出键：time中的值
effect:
7.2 Other operations
Code:
dic1 = {'name':'lwx','lover':'hanye','time':'forever'}
for i in dic1: #输出键
print(i)
for i in dic1.values(): #输出值
print(i)
for i in dic1.items(): #输出键和值
print(i)
dic1.pop('time') #删除操作
print(dic1)
dic1.setdefault('long','1314') #增加数据操作
print(dic1)
effect:
Eight .jieba library
Code:
import jieba
a= jieba.lcut('我今天要好好学python')
print(a)
b = jieba.lcut_for_search('我今天要好好学python')
print(b)
effect:
作者：罗文祥
来源：祥SHAO
原文：https://www.cnblogs.com/LWX-YEER/p/11209387.html
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