Python基础教程5章

##while 循环
name = ''
while not name.strip():
    name = raw_input("input your name:\n")
print name

##for循环
words = ['today','is','a','good','day']
for word in words:
    print word

##range函数
for i in range(1, 5):
    print i
else:
    print 'The for loop is over'

##字典的迭代
d = {'x':1,'y':2,'z':3}
for key in d:
    print key,'is correspond to',d[key]

for key in d.keys():
    print key

for value in d.values():
    print value

for key,value in d.items():
    print key,':',value

##并行迭代
names = ['annie','kevin','nic']
ages = ['21','22','23']
for i in range(len(names)):
    print names[i],'is',ages[i],'years old'

##zip函数
for name,age in zip(names,ages):
    print name,'is',age,'years old'

##索引
for index,name in enumerate(names):
    if 'annie' in name:
        names[index] = 'replaced'
print names

##列表推导式 找到名字首字母相同的男孩和女孩
girls = ['alice','benice','clarice']
boys = ['chris','arnold','bob']
print [b+'+'+g for b in boys for g in girls if b[0] == g[0]] 

##更优方案
girls = ['alice','benice','clarice']
boys = ['chris','arnold','bob']
letterGirls = {}
for girl in girls:
    letterGirls.setdefault(girl[0],[]).append(girl)
print [b+'+'+g for b in boys for g in letterGirls[b[0]]]