交换变量x = 6y = 5x, y = y, xprint x>>> 5print y>>> 6if 语句在行内print “Hello” if True else “World”>>> Hello连接
下面的最后一种方式在绑定两个不同类型的对象时显得很酷。
nfc = [“Packers”, “49ers”]afc = [“Ravens”, “Patriots”]print nfc + afc>>> [‘Packers’, ’49ers’, ‘Ravens’, ‘Patriots’]print str(1) + ” world”>>> 1 worldprint `1` + ” world”>>> 1 worldprint 1, “world”>>> 1 worldprint nfc, 1>>> [‘Packers’, ’49ers’] 1计算技巧#向下取整print 5.0//2>>> 2# 2的5次方print 2**5>> 32注意浮点数的除法print .3/.1>>> 2.9999999999999996print .3//.1>>> 2.0数值比较x = 2if 3 > x > 1: print x>>> 2if 1 < x > 0: print x>>> 2两个列表同时迭代nfc = [“Packers”, “49ers”]afc = [“Ravens”, “Patriots”]for teama, teamb in zip(nfc, afc):print teama + ” vs. ” + teamb>>> Packers vs. Ravens>>> 49ers vs. Patriots带索引的列表迭代teams = [“Packers”, “49ers”, “Ravens”, “Patriots”]for index, team in enumerate(teams):print index, team>>> 0 Packers>>> 1 49ers>>> 2 Ravens>>> 3 Patriots列表推导
已知一个列表，，刷选出偶数列表方法：
numbers = [1,2,3,4,5,6]even = []for number in numbers:if number%2 == 0:even.append(number)
用下面的代替
numbers = [1,2,3,4,5,6]even = [number for number in numbers if number%2 == 0]字典推导teams = [“Packers”, “49ers”, “Ravens”, “Patriots”]print {key: value for value, key in enumerate(teams)}>>> {’49ers’: 1, ‘Ravens’: 2, ‘Patriots’: 3, ‘Packers’: 0}初始化列表的值items = [0]*3print items>>> [0,0,0]将列表转换成字符串teams = [“Packers”, “49ers”, “Ravens”, “Patriots”]print “, “.join(teams)>>> ‘Packers, 49ers, Ravens, Patriots’从字典中获取元素
不要用下列的方式
data = {‘user’: 1, ‘name’: ‘Max’, ‘three’: 4}try: is_admin = data[‘admin’]except KeyError: is_admin = False
替换为
data = {‘user’: 1, ‘name’: ‘Max’, ‘three’: 4}is_admin = data.get(‘admin’, False)获取子列表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]
译文出处：Python初学者的17个技巧
当一个人把寂寞当作人生预约的美丽，
