即学即用的30段Python实用代码（下篇）

def has_duplicates(lst):
    return len(lst) != len(set(lst))

x = [1,2,3,4,5,5]
y = [1,2,3,4,5]
has_duplicates(x) # True
has_duplicates(y) # False

def merge_two_dicts(a, b):
    c = a.copy()   # make a copy of a 
    c.update(b)    # modify keys and values of a with the ones from b
    return c
a = {  x : 1,  y : 2}
b = {  y : 3,  z : 4}
print(merge_two_dicts(a, b)) # { y : 3,  x : 1,  z : 4}

def merge_dictionaries(a, b)
   return {**a, **b}
a = {  x : 1,  y : 2}
b = {  y : 3,  z : 4}
print(merge_dictionaries(a, b)) # { y : 3,  x : 1,  z : 4}

def to_dictionary(keys, values):
    return dict(zip(keys, values))

keys = ['a', 'b', 'c']    
values = [2, 3, 4]
print(to_dictionary(keys, values)) # { a : 2,  c : 4,  b : 3}

list = ['a', 'b', 'c', 'd']
for index, element in enumerate(list): 
    print('Value', element, 'Index ', index, )
# ( Value ,  a ,  Index  , 0)
# ( Value ,  b ,  Index  , 1)
#( Value ,  c ,  Index  , 2)
# ( Value ,  d ,  Index  , 3)

import time
start_time = time.time()
a = 1
b = 2
c = a + b
print(c) #3
end_time = time.time()
total_time = end_time - start_time
print('Time: ', total_time)
# ( Time:  , 1.1205673217773438e-05)

try:
    2*3
except TypeError:
    print('An exception was raised')
else:
    print('Thank God, no exceptions were raised.')
#Thank God, no exceptions were raised.

def most_frequent(list):
    return max(set(list), key = list.count)

list = [1,2,1,2,3,2,1,4,2]
most_frequent(list)

def palindrome(string):
    from re import sub
    s = sub( [W_] ,   , string.lower())
    return s == s[::-1]
palindrome( taco cat ) # True

import operator
action = {
    '+': operator.add,
    '-': operator.sub,
    '/': operator.truediv,
    '*': operator.mul,
    '**': pow
}
print(action[ - ](50, 25)) # 25

from copy import deepcopy
from random import randint
def shuffle(lst):
    temp_lst = deepcopy(lst)
    m = len(temp_lst)
    while (m):
        m -= 1
        i = randint(0, m)
        temp_lst[m], temp_lst[i] = temp_lst[i], temp_lst[m]
    return temp_lst

foo = [1,2,3]
shuffle(foo) # [2,3,1] , foo = [1,2,3]

def spread(arg):
    ret = []
    for i in arg:
        if isinstance(i, list):
            ret.extend(i)
        else:
            ret.append(i)
    return ret
spread([1,2,3,[4,5,6],[7],8,9]) # [1,2,3,4,5,6,7,8,9]

def swap(a, b):
  return b, a
a, b = -1, 14
swap(a, b) # (14, -1)

d = { a : 1,  b : 2}
print(d.get( c , 3)) # 3