python array 添加 python array用法

array模块的作用

目的：
    有效管理固定类型数值数据的序列。

    array模块定义了一个序列数据结构，看起来与list很相似，只不过所有成员都必须是相同的基本类型。
支持类型包括所有的数值类型或其他固定大小的基本类型（如字节）。

 

1、初始化

import array
import binascii

s = b'This is the array.'
a = array.array('b', s)

print('As byte string:', s)
print('As array      :', a)
print('As hex        :', binascii.hexlify(a))

array_string.py

运行效果

As byte string: b'This is the array.'
As array      : array('b', [84, 104, 105, 115, 32, 105, 115, 32, 116, 104, 101, 32, 97, 114, 114, 97, 121, 46])
As hex        : b'54686973206973207468652061727261792e'

2、处理数组

import array

a = array.array('i', range(3))
print('Initial :', a)

a.extend(range(3))
print('Extended:', a)

print('Slice   :', a[2:5])

print('Iterator:')
print(list(enumerate(a)))

array_sequence.py

运行效果

Initial : array('i', [0, 1, 2])
Extended: array('i', [0, 1, 2, 0, 1, 2])
Slice   : array('i', [2, 0, 1])
Iterator:
[(0, 0), (1, 1), (2, 2), (3, 0), (4, 1), (5, 2)]

3、将数组数据写入临时文件中

import array
import binascii
import tempfile

a = array.array('i', range(5))
print('A1:', a)

#  将数字数组写入临时文件
output = tempfile.NamedTemporaryFile()
a.tofile(output.file)  # must pass an *actual* file
output.flush()

# Read the raw data
with open(output.name, 'rb') as input:
    raw_data = input.read()
    print('Raw Contents:', binascii.hexlify(raw_data))

    # Read the data into an array
    input.seek(0)
    a2 = array.array('i')
    a2.fromfile(input, len(a))
    print('A2:', a2)

array_file.py

运行效果

A1: array('i', [0, 1, 2, 3, 4])
Raw Contents: b'0000000001000000020000000300000004000000'
A2: array('i', [0, 1, 2, 3, 4])

4、数组转字节，字节转数组的示例

import array
import binascii

a = array.array('i', range(5))
print('A1:', a)

as_bytes = a.tobytes()
print('Bytes:', binascii.hexlify(as_bytes))

a2 = array.array('i')
a2.frombytes(as_bytes)
print('A2:', a2)

array_tobytes.py

运行效果

A1: array('i', [0, 1, 2, 3, 4])
Bytes: b'0000000001000000020000000300000004000000'
A2: array('i', [0, 1, 2, 3, 4])

5、字节顺序的处理

import array
import binascii


def to_hex(a):
    chars_per_item = a.itemsize * 2  # 2 hex digits
    hex_version = binascii.hexlify(a)
    num_chunks = len(hex_version) // chars_per_item
    for i in range(num_chunks):
        start = i * chars_per_item
        end = start + chars_per_item
        yield hex_version[start:end]


start = int('0x12345678', 16)
end = start + 5
a1 = array.array('i', range(start, end))
a2 = array.array('i', range(start, end))
a2.byteswap()  # 会用C交换数组中元素的字节顺序，这比用Python循环处理数据高效得多。

fmt = '{:>12} {:>12} {:>12} {:>12}'
print(fmt.format('A1 hex', 'A1', 'A2 hex', 'A2'))
print(fmt.format('-' * 12, '-' * 12, '-' * 12, '-' * 12))
fmt = '{!r:>12} {:12} {!r:>12} {:12}'
for values in zip(to_hex(a1), a1, to_hex(a2), a2):
    print(fmt.format(*values))

array_byteswap.py

 

 运行效果

A1 hex           A1       A2 hex           A2
------------ ------------ ------------ ------------
 b'78563412'    305419896  b'12345678'   2018915346
 b'79563412'    305419897  b'12345679'   2035692562
 b'7a563412'    305419898  b'1234567a'   2052469778
 b'7b563412'    305419899  b'1234567b'   2069246994
 b'7c563412'    305419900  b'1234567c'   2086024210