Python一些书写技巧

x = 6
y = 5
 
x, y = y, x
 
print(x, y) #5 6

print("Hello") if True else "World" #Hello

a = [1, 2]
b = [3, 4]
print(a + b) #[1, 2, 3, 4]
 
print(str(1) + " world") #1 world
 
print(`1` + " world") #1 world
 
print(1, "world") #1 world

print(a, 3) #[1, 2] 3

print(5.0//2) #2 地板除
print(2**5) #32 2的5次方

print(.3/.1) #2.9999999999999996
print(.3//.1) #2.0

x = 2
if 3 > x > 1:
   print(x) #2

if 1 < x > 0:
   print(x) #2

names = ('Jack','Leo','Sony')
ages = (2001,2002,2003)
for a, n in zip(names, ages):
    print(a, n)
#Jack 2001
#Leo 2002
#Sony 2003

# 索引
for index, a in enumerate(names):
    print(index, a)
#0 Jack
#1 Leo
#2 Sony

numbers = [1,2,3,4,5,6]
even = []
for number in numbers:
    if number%2 == 0:
        even.append(number)

#转变成如下：
even = [number for number in numbers if number%2 == 0]

names = ['Jack','Leo','Sony']
people = [{key: value for value, key in enumerate(names)}]
print(people)
>>> [{'Sony': 2, 'Leo': 1, 'Jack': 0}]

items = [0]*3
print(items)
>>> [0,0,0]

names = ["Leo", "Jack", "Lucy"]
print(", ".join(names))
>>> Leo, Jack, Lucy

data = {'user': 1, 'name': 'Max', 'age': 4}
is_admin = data.get('admin', False)
print(is_admin)
>>> False

x = [1,2,3,4,5,6]
#前3个
print(x[:3])
>>> [1,2,3]
#中间4个
print(x[1:5])
>>> [2,3,4,5]
#最后3个
print(x[-3:])
>>> [4,5,6]
#奇数项
print(x[::2])
>>> [1,3,5]
#偶数项
print(x[1::2])
>>> [2,4,6]

for x in range(101):print("fizz"[x%3*4::]+"buzz"[x%5*4::]or x)

from collections import Counter
print(Counter("hello"))
>>> Counter({'l': 2, 'h': 1, 'e': 1, 'o': 1})

from itertools import combinations
names = ["Leo", "Jack", "Lucy"]
for name in combinations(names, 2):
    print(name)
>>> ('Leo', 'Jack')
>>> ('Leo', 'Lucy')
>>> ('Jack', 'Lucy')

False = True
if False:
   print("Hello")
else:
   print("World")
>>> Hello