Python 三 日记（二）

Python 3 日记（二）

2012-12-10 星期一

1）控制大小写

# 封装成函数print('**************************************************************')def fields(base_format, the_line, last_field = False):    num_remain = len(the_line) - struct.calcsize(base_format)    the_format = '%s %d%s' % (base_format, num_remain, last_field and 's' or 'x')    return struct.unpack(the_format, the_line)print(fields(base_format, the_line, False))print(fields(base_format, the_line, True))# 使用memorizing机制的fields版本# 适用于在循环内部调用print('**************************************************************')def fields_mem(base_format, the_line, last_field = False, _cache = {}):    key = base_format, len(the_line), last_field    the_format = _cache.get(key)    if the_format is None:        num_remain = len(the_line) - struct.calcsize(base_format)        _cache[key] = the_format = '%s %d%s' % (            base_format, num_remain, last_field and 's' or 'x')    return struct.unpack(the_format, the_line)print(fields(base_format, the_line, False))print(fields(base_format, the_line, True))# 对按字符个数分隔的方法的封装def split_by(the_line, n, last_field = False):    pieces = [the_line[k: k+n] for k in range(0, len(the_line), n)]    if not last_field and len(pieces[-1]) < n:        pieces.pop()    return piecesprint(split_by(the_line, 5, False))print(split_by(the_line, 5, True))# 将数据切成指定的列的封装def split_at(the_line, cuts, last_field = False):    pieces = [ the_line[i:j] for i, j in zip([0] + cuts, cuts + [None]) ]    if not last_field:        pieces.pop()    return piecesprint(split_at(the_line, cuts, False))print(split_at(the_line, cuts, True))# 用生成器来实现print('**************************************************************')def split_at_yield(the_line, cuts, last_field = False):    last = 0    for cut in cuts:        yield the_line[last: cut]        last = cut    if last_field:        yield the_line[last: ]        print(split_at_yield(the_line, cuts, False))print(split_at_yield(the_line, cuts, True))        def split_by_yield(the_line, n, last_field = False):    return split_at_yield(the_line, range(n, len(the_line), n), last_field)print(list(split_by_yield(the_line, 5, False)))print(list(split_by_yield(the_line, 5, True)))

**************************************************************
(b'hello ', b'python ', b'hello ')
(b'hello ', b'python ', b'hello ', b'world!')
**************************************************************
(b'hello ', b'python ', b'hello ')
(b'hello ', b'python ', b'hello ', b'world!')
[b'hello', b' keya', b'n pyt', b'hon h', b'i hel', b'lo wo']
[b'hello', b' keya', b'n pyt', b'hon h', b'i hel', b'lo wo', b'rld!']
[b'hello ', b'keyan ', b'python ', b'hi ', b'hello ']
[b'hello ', b'keyan ', b'python ', b'hi ', b'hello ', b'world!']
**************************************************************
[b'hello ', b'keyan ', b'python ', b'hi ', b'hello ']
[b'hello ', b'keyan ', b'python ', b'hi ', b'hello ', b'world!']
[b'hello', b' keya', b'n pyt', b'hon h', b'i hel', b'lo wo']
[b'hello', b' keya', b'n pyt', b'hon h', b'i hel', b'lo wo', b'rld!']