Python 将浮点数转换为字节数组
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Converting a float to bytearray
提问by tatatat0
So, what I am trying to do is convert a float to a bytearray but I keep on receiving both no input, and EXTREME slowing/freezing of my computer. My code is
所以，我想要做的是将浮点数转换为字节数组，但我一直没有收到任何输入，并且我的计算机非常缓慢/冻结。我的代码是
import struct
def float_to_hex(f):
return hex(struct.unpack('<I', struct.pack('<f', f))[0])
value = 5.1 #example value
...
value = bytearray(int(float_to_hex(float(value)), 16)
I found on another article a function to convert floats to hex which is
我在另一篇文章中发现了一个将浮点数转换为十六进制的函数，它是
def float_to_hex(f):
return hex(struct.unpack('<I', struct.pack('<f', f))[0])
and then I converted it from hex to an int. What is the problem with this? How could I better convert it from a float to bin or bytearray?
然后我将它从十六进制转换为整数。这有什么问题？我怎样才能更好地将它从浮点数转换为 bin 或 bytearray？
回答by cdarke
It depends what you want, and what you are going to do with it. If all you want is a bytearray then:
这取决于你想要什么，以及你打算用它做什么。如果你想要的只是一个字节数组，那么：
import struct
value = 5.1
ba = bytearray(struct.pack("f", value))
Where bais a bytearray. However, if you wish to display the hex values (which I suspect), then:
ba字节数组在哪里。但是，如果您希望显示十六进制值（我怀疑），则：
print([ "0x%02x" % b for b in ba ])
EDIT:
编辑：
This gives (for value 5.1):
这给出（对于值 5.1）：
['0x33', '0x33', '0xa3', '0x40']
However, CPython uses the C type doubleto store even small floats (there are good reasons for that), so:
然而，CPython 使用 C 类型double来存储甚至小的浮点数（有充分的理由），所以：
value = 5.1
ba = bytearray(struct.pack("d", value))
print([ "0x%02x" % b for b in ba ])
Gives:
给出：
['0x66', '0x66', '0x66', '0x66', '0x66', '0x66', '0x14', '0x40']
回答by jfs
The result I would want from 5.1 is 0x40 a3 33 33 or 64 163 51 51. Not as a string.
我想要 5.1 的结果是 0x40 a3 33 33 或 64 163 51 51。不是字符串。
To get the desired list of integers from the float:
要从浮点数中获取所需的整数列表：
>>> import struct
>>> list(struct.pack("!f", 5.1))
[64, 163, 51, 51]
Or the same as a bytearraytype:
或与bytearray类型相同：
>>> bytearray(struct.pack("!f", 5.1))
bytearray(b'@\xa333')
Note: the bytestring (bytestype) contains exactly the same bytes:
注意：字节串（bytes类型）包含完全相同的字节：
>>> struct.pack("!f", 5.1)
b'@\xa333'
>>> for byte in struct.pack("!f", 5.1):
... print(byte)
...
64
163
51
51
The difference is only in mutability. list, bytearrayare mutable sequences while bytestype represents an immutable sequence of bytes. Otherwise, bytesand bytearraytypes have a very similar API.
区别仅在于可变性。list,bytearray是可变序列，而bytestype 表示不可变的字节序列。否则，bytes和bytearray类型具有非常相似的 API。
