目的: 通过调整段落中的断行符的位置来格式化文本。
Python 版本: 2.5+
textwrap 模块提供了对段落的折行和填充功能。
填充段落
fill() 函数以一个文本段作为一个输入，输出一个格式化文本段。
sample_text = '''
The textwrap module can be used to format text for output in
situations where pretty-printing is desired. It offers
programmatic functionality similar to the paragraph wrapping
or filling features found in many text editors.
'''
import textwrap
print 'No dedent:\n'
print textwrap.fill(sample_text, width=50)
No dedent:
The textwrap module can be used to format
text for output in situations where pretty-
printing is desired. It offers programmatic
functionality similar to the paragraph wrapping
or filling features found in many text editors.
上例中，文本段的宽度限制为了 50，并默认进行左对齐。由于没有进行取消缩进操作，原文本中每行行首的缩进字符都会在结果中保留。
删除已有的缩进
dedent() 函数会删除源文本中各行行首的 共有 缩进部分，但会保留多出的缩进符，比如：
Line one.
Line two.
Line three.
会变成：
Line one.
Line two.
Line three.
import textwrap
dedented_text = textwrap.dedent(sample_text)
print 'Dedented:\n'
print dedented_text
Dedented:
The textwrap module can be used to format text for output in
situations where pretty-printing is desired. It offers
programmatic functionality similar to the paragraph wrapping
or filling features found in many text editors.
组合 dedent 和 fill
import textwrap
dedented_text = textwrap.dedent(sample_text).strip()
for width in [45, 70]:
print '%d Columns:\n' % width
print textwrap.fill(dedented_text, width=width)
print
45 Columns:
The textwrap module can be used to format
text for output in situations where pretty-
printing is desired. It offers programmatic
functionality similar to the paragraph
wrapping or filling features found in many
text editors.
70 Columns:
The textwrap module can be used to format text for output in
situations where pretty-printing is desired. It offers programmatic
functionality similar to the paragraph wrapping or filling features
found in many text editors.
悬挂式缩进
首行的缩进和其它行的缩进可以独立控制，从而可以实现悬挂式缩进。其中的缩进符也可以是非空白符。
import textwrap
dedented_text = textwrap.dedent(sample_text).strip()
print textwrap.fill(dedented_text,
initial_indent='',
subsequent_indent=' '*4,
width=50,
)
The textwrap module can be used to format text for
output in situations where pretty-printing is
desired. It offers programmatic functionality
similar to the paragraph wrapping or filling
features found in many text editors.