68 lines
1.7 KiB
Python
68 lines
1.7 KiB
Python
#!/usr/bin/env python
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# -*- encoding: utf-8 -*-
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"""
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Topic: 读写二进制数组结构的数据
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Desc :
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"""
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from struct import Struct
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from collections import namedtuple
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def write_records(records, format, f):
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"""
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Write a sequence of tuples to a binary file of structures.
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"""
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record_struct = Struct(format)
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for r in records:
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f.write(record_struct.pack(*r))
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def read_records(format, f):
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record_struct = Struct(format)
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chunks = iter(lambda: f.read(record_struct.size), b'')
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return (record_struct.unpack(chunk) for chunk in chunks)
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def unpack_records(format, data):
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record_struct = Struct(format)
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return (record_struct.unpack_from(data, offset)
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for offset in range(0, len(data), record_struct.size))
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if __name__ == '__main__':
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records = [(1, 2.3, 4.5),
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(6, 7.8, 9.0),
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(12, 13.4, 56.7)]
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with open('data.b', 'wb') as f:
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write_records(records, '<idd', f)
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# 增量式读取
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with open('data.b','rb') as f:
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for rec in read_records('<idd', f):
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# Process rec
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pass
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# 一次性读取，再分片解析
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with open('data.b', 'rb') as f:
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data = f.read()
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for rec in unpack_records('<idd', data):
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# Process rec
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pass
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record_struct = Struct('<idd')
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# 打印结构的字节数
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print(record_struct.size)
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# 打包数据
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a = record_struct.pack(1, 2.0, 3.0)
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print(a)
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# 解包数据
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print(record_struct.unpack(a))
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# 解包时的命名元组
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Record = namedtuple('Record', ['kind','x','y'])
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with open('data.p', 'rb') as f:
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records = (Record(*r) for r in read_records('<idd', f))
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for r in records:
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print(r.kind, r.x, r.y)
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