Python 学习随笔

1.break用法

from math import sqrt
for i in range(91,80,-1):
    root=sqrt(i)
    if root==int(root):
        print 'shi 81`````'
        break
    else:
        print 'bushi bushi '

#5.6列表推导式，轻量级循环

[(x,y) for x in str(range(1,5)) for y in 'python123' if x==y]

 输出：[('1', '1'), ('2', '2'), ('3', '3')]

girls=['abc','bcd','cde','def']
boys=['bdf','adf','cdf','ddf']
lettergirls={} #空字典
for girl in girls:
    lettergirls.setdefault(girl[0],[]).append(girl) #把girls的元素第一个索引提取出来
print [b+'+'+g for b in boys for g in lettergirls[b[0]]]

输出：['bdf+bcd', 'adf+abc', 'cdf+cde', 'ddf+def']