改变多行文本字符串的缩进

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 '
'.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 '
'.join([line[numdel:] for line in s.splitlines()])
def unIndenBlock(s):
	return delspace(s,min(numspace(s))