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Python 2.3 module textwrap can justify text in three modes: left/right/center. Sometimes 'align' mode become more useful.

Python, 144 lines
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## {{{ Recipe 414870 (r3): Align text string using spaces between words to fit specified width 
#!/usr/bin/env python
'''
align_string.py

Align string with spaces between words to fit specified width

Author: Denis Barmenkov <denis.barmenkov@gmail.com>

Copyright: this code is free, but if you want to use it, 
           please keep this multiline comment along with function source. 
           Thank you.

2005-05-22 13:27 - first revision
2010-03-09 17:01 - added align_paragraph()
2010-03-09 17:56 - added check for paragraph's last line
2010-03-09 18:16 - fork for pipe align sample script
'''
import re
import sys
import textwrap

__author__ = 'Denis Barmenkov <denis.barmenkov@gmail.com>'
#__source__ = 'http://code.activestate.com/recipes/414870/'
__source__ = 'http://code.activestate.com/recipes/577093/'

def items_len(l):
    return sum([ len(x) for x in l] )

lead_re = re.compile(r'(^\s+)(.*)$')

def align_string(s, width, last_paragraph_line=0):
    '''
    align string to specified width 
    '''
    # detect and save leading whitespace
    m = lead_re.match(s) 
    if m is None:
        left, right, w = '', s, width
    else:
        left, right, w = m.group(1), m.group(2), width - len(m.group(1))

    items = right.split()

    # add required space to each words, exclude last item
    for i in range(len(items) - 1):
        items[i] += ' '

    if not last_paragraph_line:
        # number of spaces to add
        left_count = w - items_len(items)
        while left_count > 0 and len(items) > 1:
            for i in range(len(items) - 1):
                items[i] += ' '
                left_count -= 1
                if left_count < 1:  
                    break

    res = left + ''.join(items)
    return res

def align_paragraph(paragraph, width, debug=0):
    '''
    align paragraph to specified width,
    returns list of paragraph lines
    '''
    lines = list()
    if type(paragraph) == type(lines):
        lines.extend(paragraph)
    elif type(paragraph) == type(''):
        lines.append(paragraph)
    elif type(paragraph) == type(tuple()):
        lines.extend(list(paragraph))
    else:
        raise TypeError, 'Unsopported paragraph type: %r' % type(paragraph)

    flatten_para = ' '.join(lines)

    splitted = textwrap.wrap(flatten_para, width) 
    if debug:
        print 'textwrap:\n%s\n' % '\n'.join(splitted)

    wrapped = list()
    while len(splitted) > 0:
        line = splitted.pop(0)
        if len(splitted) == 0:
            last_paragraph_line = 1
        else:
            last_paragraph_line = 0
        aligned = align_string(line, width, last_paragraph_line)
        wrapped.append(aligned)

    if debug:
        print 'textwrap & align_string:\n%s\n' % '\n'.join(wrapped)

    return wrapped

def align_pipe(width, inpipe=None, outpipe=None):
    '''
    read paragraphs from one pipe, 
    align them and puts to second pipe
    '''
    if inpipe is None:
        inpipe = sys.stdin
    if outpipe is None:
        outpipe = sys.stdout

    paragraph_lines = list()

    def flush_paragraph(paragraph_lines):
        '''
        align paragraph, put to output, 
        reset state
        '''
        if len(paragraph_lines) > 0:
            aligned_paragraph = align_paragraph(paragraph_lines, width)
            for line in aligned_paragraph:
                outpipe.write(line + '\n')
            paragraph_lines = list()

        return paragraph_lines

    for rawline in inpipe:
        line = rawline.splitlines()[0]

        # paragraph closed by empty line
        if line.strip() == '':
            paragraph_lines = flush_paragraph(paragraph_lines)
            outpipe.write('\n')
            continue

        # paragraph started with space
        if line[0].isspace():
            paragraph_lines = flush_paragraph(paragraph_lines)

        paragraph_lines.append(line)

    paragraph_lines = flush_paragraph(paragraph_lines)

if __name__ == '__main__':
    width = 75
    # or 
    # width = int(sys.argv[1])
    align_pipe(width)

Call this script on *nixes:

chmod +x align_pipe.py
cat text_file | align_pipe.py

or on Windows:

type text_file | python align_pipe.py

See also: http://docs.python.org/using/index.html

1 comment

Zaq 11 years, 9 months ago  # | flag

Thank you very much!

Your script will help me a lot. I am too impressed that fast way you code.

Thanks a lot from Brazil!