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thinkpython上的一个识别数据结构，返回描述他们形状的字符串

"""This module contains a code example related toThink Python, 2nd Editionby Allen Downeyhttp://thinkpython2.comCopyright 2015 Allen DowneyLicense: http://creativecommons.org/licenses/by/4.0/"""from __future__ import print_function, division"""This module provides one function, structshape(), which takesan object of any type and returns a string that summarizes the"shape" of the data structure; that is, the type, size andcomposition."""def structshape(ds):    """Returns a string that describes the shape of a data structure.    ds: any Python object    Returns: string    """    typename = type(ds).__name__#这句为了得到名字的方法    # handle sequences    sequence = (list, tuple, set, type(iter('')))    if isinstance(ds, sequence):        t = []        for i, x in enumerate(ds):            t.append(structshape(x))        rep = '%s of %s' % (typename, listrep(t))        return rep    # handle dictionaries    elif isinstance(ds, dict):        keys = set()        vals = set()        for k, v in ds.items():            keys.add(structshape(k))            vals.add(structshape(v))        rep = '%s of %d %s->%s' % (typename, len(ds),                                    setrep(keys), setrep(vals))        return rep    # handle other types    else:        if hasattr(ds, '__class__'):            return ds.__class__.__name__        else:            return typenamedef listrep(t):    """Returns a string representation of a list of type strings.    t: list of strings    Returns: string    """    current = t[0]    count = 0    res = []    for x in t:        if x == current:            count += 1        else:            append(res, current, count)            current = x            count = 1    append(res, current, count)    return setrep(res)def setrep(s):    """Returns a string representation of a set of type strings.    s: set of strings    Returns: string    """    rep = ', '.join(s)    if len(s) == 1:        return rep    else:        return '(' + rep + ')'    return def append(res, typestr, count):    """Adds a new element to a list of type strings.    Modifies res.    res: list of type strings    typestr: the new type string    count: how many of the new type there are    Returns: None    """    if count == 1:        rep = typestr    else:        rep = '%d %s' % (count, typestr)    res.append(rep)if __name__ == '__main__':    t = [1, 2, 3]    print(structshape(t))    t2 = [[1, 2], [3, 4], [5, 6]]    print(structshape(t2))    t3 = [1, 2, 3, 4.0, '5', '6', [7], [8], 9]    print(structshape(t3))    class Point:        """trivial object type"""    t4 = [Point(), Point()]    print(structshape(t4))    s = set('abc')    print(structshape(s))    lt = zip(t, s)    print(structshape(lt))    d = dict(lt)            print(structshape(d))    it = iter('abc')    print(structshape(it))

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