你应该学习的 20 个 Python 代码段

    # Reversing a string using slicing      my_string = "ABCDE"  reversed_string = my_string[::-1]  print(reversed_string)    # Output  # EDCBA

    my_string = "my name is chaitanya baweja"    # using the title() function of string class  new_string = my_string.title()  print(new_string)   # Output  # My Name Is Chaitanya Baweja

    my_string = "aavvccccddddeee"    # converting the string to a set  temp_set = set(my_string)    # stitching set into a string using join  new_string = ''.join(temp_set)    print(new_string)

    n = 3 # number of repetitions
  my_string = "abcd"  my_list = [1,2,3]
  print(my_string*n)  # abcdabcdabcd
  print(my_list*n)  # [1,2,3,1,2,3,1,2,3]

n = 4my_list = [0]*n # n denotes the length of the required list# [0, 0, 0, 0]

    # Multiplying each element in a list by 2    original_list = [1,2,3,4]    new_list = [2*x for x in original_list]    print(new_list)  # [2,4,6,8]

    a = 1  b = 2    a, b = b, a
  print(a) # 2  print(b) # 1

    string_1 = "My name is Chaitanya Baweja"  string_2 = "sample/ string 2"    # default separator ' '  print(string_1.split())  # ['My', 'name', 'is', 'Chaitanya', 'Baweja']    # defining separator as '/'  print(string_2.split('/'))  # ['sample', ' string 2']

    list_of_strings = ['My', 'name', 'is', 'Chaitanya', 'Baweja']    # Using join with the comma separator  print(','.join(list_of_strings))
  # Output  # My,name,is,Chaitanya,Baweja

    my_string = "abcba"    if my_string == my_string[::-1]:      print("palindrome")  else:      print("not palindrome")
  # Output  # palindrom

    # finding frequency of each element in a list  from collections import Counter    my_list = ['a','a','b','b','b','c','d','d','d','d','d']  count = Counter(my_list) # defining a counter object    print(count) # Of all elements  # Counter({'d': 5, 'b': 3, 'a': 2, 'c': 1})    print(count['b']) # of individual element  # 3    print(count.most_common(1)) # most frequent element  # [('d', 5)]

    from collections import Counter
  str_1, str_2, str_3 = "acbde", "abced", "abcda"  cnt_1, cnt_2, cnt_3  = Counter(str_1), Counter(str_2), Counter(str_3)
  if cnt_1 == cnt_2:      print('1 and 2 anagram')  if cnt_1 == cnt_3:      print('1 and 3 anagram')

    a, b = 1,0
  try:      print(a/b)      # exception raised when b is 0  except ZeroDivisionError:      print("division by zero")  else:      print("no exceptions raised")  finally:      print("Run this always"

    my_list = ['a', 'b', 'c', 'd', 'e']    for index, value in enumerate(my_list):      print('{0}: {1}'.format(index, value))
  # 0: a  # 1: b  # 2: c  # 3: d  # 4: e

    import sys    num = 21
  print(sys.getsizeof(num))
  # In Python 2, 24  # In Python 3, 28

    dict_1 = {'apple': 9, 'banana': 6}  dict_2 = {'banana': 4, 'orange': 8}    combined_dict = {**dict_1, **dict_2}
  print(combined_dict)  # Output  # {'apple': 9, 'banana': 4, 'orange': 8}

    import time    start_time = time.time()  # Code to check follows  a, b = 1,2  c = a+ b  # Code to check ends  end_time = time.time()  time_taken_in_micro = (end_time- start_time)*(10**6)    print(" Time taken in micro_seconds: {0} ms").format(time_taken_in_micro)

    from iteration_utilities import deepflatten    # if you only have one depth nested_list, use this  def flatten(l):    return [item for sublist in l for item in sublist]
  l = [[1,2,3],[3]]  print(flatten(l))  # [1, 2, 3, 3]
  # if you don't know how deep the list is nested  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]

    import random    my_list = ['a', 'b', 'c', 'd', 'e']  num_samples = 2
  samples = random.sample(my_list,num_samples)  print(samples)  # [ 'a', 'e'] this will have any 2 random values

    import secrets                            # imports secure module.  secure_random = secrets.SystemRandom()    # creates a secure random object.
  my_list = ['a','b','c','d','e']  num_samples = 2    samples = secure_random.sample(my_list, num_samples)
  print(samples)  # [ 'e', 'd'] this will have any 2 random values

    num = 123456    # using map  list_of_digits = list(map(int, str(num)))
  print(list_of_digits)  # [1, 2, 3, 4, 5, 6]    # using list comprehension  list_of_digits = [int(x) for x in str(num)]    print(list_of_digits)  # [1, 2, 3, 4, 5, 6]

    def unique(l):      if len(l)==len(set(l)):          print("All elements are unique")      else:          print("List has duplicates")
  unique([1,2,3,4])  # All elements are unique    unique([1,1,2,3])  # List has duplicates