Python初学者的17个技巧

x = 6y = 5x, y = y, xprint x>>> 5print y>>> 6

print "Hello" if True else "World">>> Hello

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

#向下取整print 5.0//2>>> 2# 2的5次方print 2**5>> 32

print .3/.1>>> 2.9999999999999996print .3//.1>>> 2.0

x = 2if 3 > x > 1:
   print x>>> 2if 1 < x > 0:
   print x>>> 2

nfc = ["Packers", "49ers"]afc = ["Ravens", "Patriots"]for teama, teamb in zip(nfc, afc):
     print teama + " vs. " + teamb>>> Packers vs. Ravens>>> 49ers vs. Patriots

teams = ["Packers", "49ers", "Ravens", "Patriots"]for index, team in enumerate(teams):
    print index, team>>> 0 Packers>>> 1 49ers>>> 2 Ravens>>> 3 Patriots

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

numbers = [1,2,3,4,5,6]even = [number for number in numbers if number%2 == 0]

teams = ["Packers", "49ers", "Ravens", "Patriots"]print {key: value for value, key in enumerate(teams)}>>> {'49ers': 1, 'Ravens': 2, 'Patriots': 3, 'Packers': 0}

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

teams = ["Packers", "49ers", "Ravens", "Patriots"]print ", ".join(teams)>>> 'Packers, 49ers, Ravens, Patriots'

data = {'user': 1, 'name': 'Max', 'three': 4}try:
   is_admin = data['admin']except KeyError:
   is_admin = False

data = {'user': 1, 'name': 'Max', 'three': 4}is_admin = data.get('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 Counterprint Counter("hello")>>> Counter({'l': 2, 'h': 1, 'e': 1, 'o': 1})

from itertools import combinations
teams = ["Packers", "49ers", "Ravens", "Patriots"]for game in combinations(teams, 2):
    print game>>> ('Packers', '49ers')>>> ('Packers', 'Ravens')>>> ('Packers', 'Patriots')>>> ('49ers', 'Ravens')>>> ('49ers', 'Patriots')>>> ('Ravens', 'Patriots')

False = Trueif False:
   print "Hello"else:
   print "World">>> Hello