python小技巧

my_string =  "啊，生存还是毁灭  "
 reversed_string = my_string[::-1 ] 

my_string =  "  my name is wei xiang  "  #  通过title()来实现首字母大写 
new_string = my_string.title()
 print (new_string) # My Name Wei Xiang 

my_string =  "dddbbeacf  "  #  通过set()来进行去重 
temp_set = set(my_string) #  通过join()来进行连接 
new_string =  '' .join(temp_set)
 print (new_string)  #  dfbcae 

string_1 =  "  My name is kaixin mahua  "  string_2 =  "开心  , 麻 1, 花 2  "  #  默认的分隔符是空格，来进行拆分 
 print (string_1.split()) #  ['My', 'name', 'is', 'kaixin', 'mahua'] 
 print (string_2.split( '  ,  ' )) #  ['开心', '麻 1', '花 2'] 

list_of_strings = [ '  My  ' ,  '  name  ' ,  '  is  ' ,  'DongMei  ' ,  'DaQiao  ' ] #  通过空格和join来连词成句 
 print ( '   ' .join(list_of_strings)) #  My name is DongMei DaQiao 

 from  collections  import  Counter

my_list = [ 'a  ' , 'a  ' , '  b  ' , '  b  ' , '  b  ' , '  c  ' , '  d  ' , '  d  ' , '  d  ' , '  d  ' , '  d  '  ]

count = Counter(my_list)  print (count)  #  Counter({'d': 5, 'b': 3, 'a': 2, 'c': 1}) 
 print (count[ '  b  ' ])  #  单独的“b”元素出现的次数# 3 
 print (count.most_common(1))  #  出现频率最多的元素# [('d', 5)] 

dict_1 = { '  apple  ' : 0,  '  banana  ' : 3 }

dict_2 = { '  grape  ' : 1,  '  orange  ' : 9 }  #  方法一 
combined_dict = {**dict_1, ** dict_2}
  #  方法二 
 dict_1.update(dict_2)
  #  方法三 
 print (dict(dict_1.items() | dict_2.items()))  #  {'apple': 0, 'banana': 3, 'grape': 1, 'orange': 9} 

 import  time

start_time = time.time()

end_time = time.time()

time_taken_in_micro = (end_time - start_time) * (10 ** 6 )  print (time_taken_in_micro)

 from iteration_utilities  import deepflatten

l = [[1,2,3],[4,[5],[6,7]],[8,[9,[10 ]]]]

 print(list(deepflatten(l, depth=3)))  # [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]       

 def  unique(l):

　　  if  len(l)== len(set(l)):

　　　　  print ( "  不存在重复值  " )
 　　else :
 　　　　print ( "  存在重复值  "  )

unique([t ,l,p]) #  不存在重复值 
unique([l,t,t]) #  存在重复值 

array = [[ 'l  ' ,  '3  ' ], [ 't  ' ,  '2  ' ], [ 't  ' ,  '1  '  ]]

transposed =  zip (* array)  print (list(transposed))  #  [('l', 't', 't'), ('3', '2', '1')] 

 def  difference(a, b):

　　set_a = set(a)

　　set_b = set(b)

　　comparison = set_a.difference(set_b)

　　  return  list(comparison) #  返回第一个列表的不同的元素 
difference([1,2,6], [1,2,5]) #  [6] 

 def  to_dictionary(keys, values):

　　  return  dict( zip (keys, values))   

keys = [ " 三 " ,  " 二 " ,  "  意  "  ]

values = [3, 2, 1 ]  print (to_dictionary(keys, values))   #  {'三': 3, '二': 2, '意': 1} 

d = { '  apple  ' : 9,  '  grape  ' : 4,  '  banana  ' : 6,  '  orange  ' : 8 }  #  方法一 
sorted(d.items(), key =  lambda  x: x[1])  #  从小到大排序# [('grape', 4), ('banana', 6), ('orange', 8), ('apple', 9)] 
sorted(d.items(), key =  lambda  x: x[1], reverse = True)  #  从大到小排序# [('apple', 9), ('orange', 8), ('banana', 6), ('grape', 4)]  #  方法二 
 from  operator  import  itemgetter  print (sorted(d.items(), key = itemgetter(1)))  #  [('grape', 4), ('banana', 6), ('orange', 8), ('apple', 9)] 

 1  list1 = [1,2,3,2,1 ]  2   print (list1.index(max(list1)))   #  2 
 3   print (list1.index(min(list1)))   #  0 

 #  案例1 
a = [1,2 ]

b = a

a = a + [3, 4]  #  会生成一个新列表 
 print (a)  #  [1,2,3,4] 
 print (b)  #  [1,2]  #  案例2 
a = [1,2 ]

b = a

a += [3, 4]   #  相当于extend,列表a后直接添加元素 
 print (a)  #  [1,2,3,4] 
 print (b)  #  [1,2,3,4] 

list = [3, 1, 9 ]

a, b, c = list    #  a=3,b=1,c=9 
 def  f():  return  6 0 1 q, w, e = f()     #  q=6,w=0,e=1 

 import  sys

value =  "  helo moto  "  sys. getsizeof (value) 

values = {i : i*i  for  i  in  range(3)}  #  {0:0, 1:1, 2:4} 

 import  emoji

emoji.emojize(  '  Python is :thumbs_up:  ' ) #  返回的一个大拇指表情 

x = [1, 2, 3 ]

y =  map ( lambda  x : x ** 2 , x)  # 映射  print (list(y))  #  [1, 4, 9] 

 import  sh

sh.echo(  "  情系中国结，联通四海心  " ) #  返回“情系中国结，联通四海心” 
sh.which( "  python  " )   #  返回python所在路径 

a, *mid, b = [1, 2, 3, 4, 5, 6 ]  print (a, mid, b)    #  1 [2, 3, 4, 5] 

L = [1,3,5,7 ]

a, _, b, _ = L  print (a,b)   #  1  5 

 def  fun():  pass 
 #定义一个函数但尚未弄清楚如何实现它时，可以放置。  或者： 
 def  fun():

　　... 

a = [1,3 ]

b = a.copy()  #  这里还可以用  b = a[:] 
b[0]=3
 print (a,b)   #  [1,3] [3,3] 

lang =  '  python  ' 
 print (f '  {lang} is most popular language in the world  '  )  print ( '  I like {}  '  .format(lang))  print ( '  I like %s  ' %(lang))   #  I like python 

 def  sheng(input):  return   lambda : "  省前  "  + input() +  "  省后  " 
 def  shi(input):  return   lambda : "  市前  "  + input() +  "  市后  "  @sheng

@shi  def  run():  return   "  泗阳县  " 
 print (run())   #  省前 市前 泗阳县 市后 省后 

 print ( "  http://foofish.net  " .startswith(( '  http  ' , '  https  ' )))  #  True 
 print ( "  http://foofish.net  " .endswith(( '  net  ' , '  https  ' )))  #  True