blocks|key|1741119|text|float(int('-0b1110',0))|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1741120|这对我很有效。|unstyled|1741121|如果您有一个表示浮点数而不是整数的64位字符串，则可以执行三步转换-第一步将字符串转换为整数，第二步将其转换为8字节字符串，第三步将这些位重新解释为浮点数。|1741122|>>>+import+struct
>>>+s+=+'0b0100000000101001000101111000110101001111110111110011101101100100'
>>>+q+=+int(s,+0)
>>>+b8+=+struct.pack('Q',+q)
>>>+struct.unpack('d',+b8)[0]
12.546|1741123|当然，您可以将所有这些步骤合并到一行中。|1741124|>>>+s2+=+'0b1100000000101100000000000000000000000000000000000000000000000000'
>>>+struct.unpack('d',+struct.pack('Q',+int(s2,+0)))[0]
-14.0|1741125|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$B|C]]|$1|K|3|L|5|F|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$B|C]]|$1|O|3|-4|5|F|7|W|8|@]|9|@]|A|$]]]|P|$]]

<pre><code>float(int('-0b1110',0))
</code></pre>

That works for me.

If you have a 64-bit string that represents a floating point number rather than an integer, you can do a three-step conversion - the first step turns the string into an integer, the second converts it into an 8-byte string, and the third re-interprets those bits as a float.

<pre><code>&gt;&gt;&gt; import struct
&gt;&gt;&gt; s = '0b0100000000101001000101111000110101001111110111110011101101100100'
&gt;&gt;&gt; q = int(s, 0)
&gt;&gt;&gt; b8 = struct.pack('Q', q)
&gt;&gt;&gt; struct.unpack('d', b8)[0]
12.546
</code></pre>

Of course you can combine all those steps into a single line.

<pre><code>&gt;&gt;&gt; s2 = '0b1100000000101100000000000000000000000000000000000000000000000000'
&gt;&gt;&gt; struct.unpack('d', struct.pack('Q', int(s2, 0)))[0]
-14.0
</code></pre>

blocks|key|1741198|text|如果需要，您可以使用eval('')，然后将其转换为浮点数。示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1741199|>>+eval('-0b1110')
-14
>>+float(eval('-0b1110'))
-14.0|code-block|syntax|javascript|1741200|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You could use eval('') and then cast it as a float if needed. Example: 

<pre><code>&gt;&gt; eval('-0b1110')
-14
&gt;&gt; float(eval('-0b1110'))
-14.0
</code></pre>

blocks|key|1954662|text|另一种选择是这样做|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1954663|from+ast+import+literal_eval

float_str+=+"-0b101010101"
result+=+float(literal_eval(float_str))|code-block|syntax|javascript|1954664|与内置的"eval“不同，literal_eval即使在用户输入上运行也是安全的，因为它只能解析Python文字-并且不会执行表达式，这意味着它也不会调用函数。|1954665|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Another option is to do

<pre><code>from ast import literal_eval

float_str = "-0b101010101"
result = float(literal_eval(float_str))
</code></pre>

Unlike the built-in "eval", literal_eval is safe to be run even on user inputs, as it can only parse Python literals - and will not execute expressions, which means it will not call functions as well.

blocks|key|1741320|text|这对我很有效。使用Python3.4测试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1741321|def+float_to_bin(num):
++++return+bin(struct.unpack('!I',+struct.pack('!f',+num))[0])[2:].zfill(32)

def+bin_to_float(binary):
++++return+struct.unpack('!f',struct.pack('!I',+int(binary,+2)))[0]

float_to_bin(bin_to_float(float_to_bin(123.123)))+==+float_to_bin(123.123)
>>>+True|code-block|syntax|javascript|1741322|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This works for me.
Tested with Python3.4:

<pre><code>def float_to_bin(num):
 return bin(struct.unpack('!I', struct.pack('!f', num))[0])[2:].zfill(32)

def bin_to_float(binary):
 return struct.unpack('!f',struct.pack('!I', int(binary, 2)))[0]

float_to_bin(bin_to_float(float_to_bin(123.123))) == float_to_bin(123.123)
&gt;&gt;&gt; True
</code></pre>

blocks|key|1954732|text|def+bin_to_float(binary):
++++di+=+binary.find('.')
++++if+di+==+-1:
++++++++return+int(binary,2)
++++else:
++++++++whole+=+binary[:di]+or+'0'
++++++++fraction+=+binary+[di%2B1:]+or+'0'
++++++++return+int(whole,2)+%2B+int(whole,2)/abs(int(whole,2))+*+int(fraction,2)+/+2**+len(fraction)

samples+=+[
++++'-0b1110.010101011',
++++'-0b1001110',
++++'101',
++++'0b1110010.11010111011',
++++'1100.',
++++'-00011',
++++'%2B0b1100.0011',
]

for+binary+in+samples:
++++print(binary,'=',bin_to_float(binary))|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1954733|返回|unstyled|1954734|-0b1110.010101011+=+-14.333984375
-0b1001110+=+-78
101+=+5
0b1110010.11010111011+=+114.84130859375
1100.+=+12.0
-00011+=+-3
%2B0b1100.0011+=+12.1875|1954735|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>def bin_to_float(binary):
 di = binary.find('.')
 if di == -1:
 return int(binary,2)
 else:
 whole = binary[:di] or '0'
 fraction = binary [di+1:] or '0'
 return int(whole,2) + int(whole,2)/abs(int(whole,2)) * int(fraction,2) / 2** len(fraction)

samples = [
 '-0b1110.010101011',
 '-0b1001110',
 '101',
 '0b1110010.11010111011',
 '1100.',
 '-00011',
 '+0b1100.0011',
]

for binary in samples:
 print(binary,'=',bin_to_float(binary))
</code></pre>
Returns
<pre><code>-0b1110.010101011 = -14.333984375
-0b1001110 = -78
101 = 5
0b1110010.11010111011 = 114.84130859375
1100. = 12.0
-00011 = -3
+0b1100.0011 = 12.1875
</code></pre>

I want to convert a binary number into a float number. Here's an example of a possibility:

<pre><code>&gt;&gt;&gt; float(-0b1110)
</code></pre>

gives me the correct output:

<pre><code>-14.0
</code></pre>

Unfortunately, I am working with binary strings, i.e., I need something like <code>float('-0b1110')</code>. 
However, this doesn't work:

<pre class="lang-none prettyprint-override"><code>&gt;&gt;&gt; float('-0b1110')
Traceback (most recent call last):
 File "&lt;stdin&gt;", line 1, in &lt;module&gt;
ValueError: invalid literal for float(): -0b1110
</code></pre>

I tried to use <code>binascii.a2b_qp(string[, header])</code> which converts a block of quoted-printable data back to binary and returns the binary data. But eventually, I get the same error:

<pre class="lang-none prettyprint-override"><code>&gt;&gt;&gt; float(binascii.a2b_qp('-0b1110'))
Traceback (most recent call last):
 File "&lt;stdin&gt;", line 1, in &lt;module&gt;
ValueError: invalid literal for float(): -0b1110
</code></pre>

I understand the cases where the output number is an integer but what if I want to obtain the number 12.546? What would the function call for the binary string look like then?

How to convert a binary (string) into a float value?

Python

我想把二进制数转换成浮点数。以下是一种可能性的示例：>>> float(-0b1110)给出了正确的输出：-14.0不幸的是，我使用的是二进制字符串，也就是说，我需要像float('-0b1110')这样的东西。然而，这不起作用：>>> float('-0b1110')Traceback (most recent ca...

问如何将二进制(字符串)转换为浮点值？
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