python练习1

1、链式比较

i=3
print(1<i<3)  #False
print(1<i<=3)#True

2、不用else和if实现计算器

from operator import  *
def calculator(a,b,k):
    return {
        '+':add,
        '-':sub,
        '*':mul,
        '/':truediv,
        '**':pow
    }[k](a,b)

print(calculator(1,2,'+')) #3
print(calculator(8,4,'/')) #2.0

3、求字符串的字节长度

def str_byte_len(mystr):
    return (len(mystr.encode('utf-8')))

print(str_byte_len('i love python')) #13

4、寻找第n次出现的位置

def search_n(s,c,n):
    size=0
    for i,x in enumerate(s):
        if x==c:
            size+=1
        if size==n:
            return i
    return -1
print(search_n('hgfdsfhbsdbjfbsdjfnj','f',4))   #17
print(search_n('hgfdsfhbsdbjfbsdjfnj','f',40))  #-1

5、去掉最高最低求平均

def score_mean(lst):
    lst.sort()
    lst2=lst[1:(len(lst)-1)]
    return round((sum(lst2)/len(lst2)),2)  #round返回浮点数的四舍五入值

print(score_mean([9.1, 9.0,8.1, 9.7, 19,8.2, 8.6,9.8]))# 9.07

6、打印乘法表

def printnxn(n):
    for i in range(1,n+1):
        for j in range(1,i+1):
            # print("{}x{}={}\t".format(i,j,i*j),end=' ')
            print("%d x %d =%d \t"%(i,j,i*j),end=' ')
        print()
printnxn(9)

7、输出路径下以.html结尾的文件路径信息

def print_html_dir(html_path):
    path_list=os.listdir(html_path)
    for i in path_list:
        path=os.path.join(html_path,i)
        if os.path.isdir(path):
            print_html_dir(path)
        if path.endswith(".html"):
            print(path)

path=r"F:\测试\脚本\daily_test\analysis"
print_html_dir(path)

8、替换列表汇中所有的3为3a:

num=['harden3','lam3pard',3,33,333,34,45,56,76,87,78,45,3,32,13,56,4231,7653,876,32]

num_1=list(map(str,num))
for index,i in enumerate(num_1,0):
    # if isinstance(i,basestring):
    if i.find('3')>=0:
        num_1[index]=num_1[index].replace('3','3a')
    elif i.isdigit():
        num_1[index]=int(num_1[index])
print(num_1)

9、合并去重

list1=[2,3,4,6,8,9]
list2=[1,2,5,4,6,9,11,15,21,23]
list3=list1+list2
print(list(set(list3)))

10、#随机生成验证码

import random
list1=[]
for i in range(65,91):
    list1.append(chr(i)) #通过for循环遍历asii追加到空列表中
for j in range(97,123):
    list1.append(chr(j))
for k in range(48,58):
    list1.append(chr(k))
ma=random.sample(list1,6)
ma=''.join(ma)
print(ma)

#2
import string
str1="0123456789"
str2=string.ascii_letters
str3=str1+str2
ma1=random.sample(str3,6)
ma1=''.join(ma1)
print(ma1)

11、判断闰年

def if_runnian(year):
    if(year % 4)==0:
        if(year % 100)==0:
            if (year % 400)==0:
                print("{0}是闰年".format(year))
            else:
                print("{0}不是闰年".format(year)) #正百年不能被400整除的不是闰年
        else:
            print("{0}是闰年".format(year))  #非正百年能被4整除的为闰年
    else:
        print("{0}不是闰年".format(year))


def if_runnian1(year):
    if (year % 4)==0 and (year%100)!=0 or (year%400)==0:
        print("{0}是闰年".format(year))
    else:
        print("{0}不是闰年".format(year))

def if_runnian2(year):
    check_year= calendar.isleap(year)
    if check_year==True:
        print("%d是闰年"%year)
    else:
        print("%d是平年"%year)

12、最大公约数

def hcf(x,y):
   if x>y:
       smaller=y
   else:
       smaller=x
   for i in range(1,smaller+1):
       if (x%i==0) and (y%i==0):
           hcf=i
   return hcf

13、最小公倍数

def lcm(x,y):
    if x>y:
        greater=x
    else:
        greater=y

    while(True):
        if ((greater%x==0) and (greater%y==0)):
            lcm=greater
            break
        greater+=1
    return lcm

14、嵌套数组完全展开

def flatten(input_arr,output_arr=None):
    if output_arr is None:
        output_arr=[]
    for ele in input_arr:
        if isinstance(ele,Iterable):
            flatten(ele,output_arr)
        else:
            output_arr.append(ele)
    return output_arr

print(flatten([[1,2,3],[4,5]], [6,7])) # [6, 7, 1, 2, 3, 4, 5]

15、将list等分为子组

from math import  ceil

def divide(lst,size):
    if size<=0:
        return lst
    return [lst[i*size:(i+1)*size] for i in range(0,ceil(len(lst)/size))]

r=divide([1,3,4,5,2,7,8,34,5],3) #[[1, 3, 4], [5, 2, 7], [8, 34, 5]]

16、生成斐波拉茨序列的前n项

def fibonacci(n):
    if n<=1:
        return [1]
    fib=[1,1]
    while len(fib)<n:
        fib.append(fib[len(fib)-1]+fib[len(fib)-2])
    return fib
print(fibonacci(11))  #[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]

17、出现最多元素

def max_frequency(lst):
    return max(lst,default='列表为空',key=lambda v:lst.count(v))
lst=[1,3,4,3,4,2,1,3,'a','a','a','a']
print(max_frequency(lst))

18、求列表中所有重复元素

from collections import Counter

def find_all_duplicates(lst):
    c = Counter(lst)   #Counter({3: 4, 2: 3, 1: 2})
    return list(filter(lambda k: c[k] > 1, c))   #k 为key值

find_all_duplicates([1, 2, 2, 3, 3, 3])  # [2,3]

19、字典值最大的键值对列表

def max_pairs(dic):
    if len(dic) == 0:
        return dic
    max_val = max(map(lambda v: v[1], dic.items())) #返回的是(key,value)d的列表
    return [item for item in dic.items() if item[1] == max_val]

max_pairs({'a': -10, 'b': 5, 'c': 3, 'd': 5})# [('b', 5), ('d', 5)]

20、求字典钱n个最大值

from heapq import nlargest

def topn_dict(d,n):
    return nlargest(n,d,key=lambda k:d[k])   #主要是nlargest()函数的使用

dic1={'a': 10, 'b': 8, 'c': 9, 'd': 10}
print(topn_dict(dic1,2))

21、查找指定文件格式文件

import os
def find_file(work_dir,extension='jpg'):
    lst=[]
    for filename in os.listdir(work_dir):
        splits=os.path.splitext(filename)  #返回的是（''test','.py'）拆分扩展名
        ext=splits[1]
        if ext=='.'+extension:
            lst.append(filename)
    return lst
print(find_file('.','py'))