Python输出以提高浮点精度

Question

The following:

>>>import struct
>>>struct.unpack('!d', ('40d11998e5035288').decode('hex'))[0]
>>>
>>>17510.3889778429

I would like to be able to print the value 17510.3889778429 to a .csv output file. For some reason, when I write this to a file, it rounds the decimal and only writes:

17510.3889778

How would I print this with higher precision?

Thanks, Ned

Answer 1

Assuming you're using Python's csv module, the documentation says that non-string data is formatted using str() , and that seems to be where the truncation is happening. So one thing you could do is define your own class that stringizes the way you want:

class myFloat( float ):
    def __str__(self):
        return "%.12f"%self

 x = myFloat( 17510.3889778429 )
 print "%s"%x

Yields:

17510.388977842900

Answer 2

You can convert the number to a string using any appropriate method and write the string to the CSV.

>>> x = 17510.3889778429
>>> s = str(x)
>>> s
'17510.3889778'
>>> s = '%17.11f' % x
>>> s
'17510.38897784290'