改变多行文本字符串的缩进
任务:有个包含多行文本的字符串，需要创建该字符串的一个拷贝，并在每行行首添加或者删除一些空格，以保证每行的缩进都是指定数目的空格
mulLine = """Hello!!!
Wellcome to Python's world!
There are a lot of interesting things!
Enjoy yourself. Thank you!"""
print ''.join(mulLine.splitlines())
print '------------'
print ''.join(mulLine.splitlines(True))
输出结果：
Hello!!! Wellcome to Python's world! There are a lot of interesting things! Enjoy yourself. Thank you!
------------
Hello!!!
Wellcome to Python's world!
There are a lot of interesting things!
Enjoy yourself. Thank you!
字符串对象已经提供了趁手的工具，写个简单的函数即可：
>>> def reindent(s,numspace):
... leading_space=numspace*' '
... lines=[leading_space+line.strip() for line in s.splitlines()]
... return '\n'.join(lines)
...
>>> x="""
... line one
... line two
... and line three
... """
>>> print reindent(x,2)
line one
line two
and line three
一个常建的需求是调整每行行首的空格数，并确保整块文本的行之间的相对缩进不发生变化，无论是正向还是反向调整，都可以，不过反向调整需要检查一下每行行首的空格，以确保不会把非空字符截去。因此，我们需要将这个任务分解，用两个函数拉完成，再 加上一个计算每行行首空格并返回一个列表的函数，
#!/usr/bin/env python
def addSpace(s,num):
white=" "*num
return white+white.join(s.splitlines(True))
def numspaces(s):
return [(len(line)-len(line.lstrip)) for line in s.splitlines()]
def delspace(s,numdel):
if numdel>min(numspace(s)):
raise ValueError,"removing more spaces than there are"
return '\n'.join([line[numdel:] for line in s.splitlines()])
def unIndenBlock(s):
return delspace(s,min(numspace(s))