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List of integers

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  List of integers KP <kai.peters@gmail.com> - 2015-12-13 16:24 -0800
    Re: List of integers Chris Angelico <rosuav@gmail.com> - 2015-12-14 11:32 +1100
      Re: List of integers KP <kai.peters@gmail.com> - 2015-12-13 19:11 -0800
    Re: List of integers Terry Reedy <tjreedy@udel.edu> - 2015-12-14 04:56 -0500
      Re: List of integers Steven D'Aprano <steve@pearwood.info> - 2015-12-14 21:37 +1100

#100398 — List of integers

data = list(f.read(4))
print data

from a binary file might give

['\x10', '\x20', '\x12', '\x01']


How can I receive this instead?

[0x10, 0x20, 0x12, 0x01]

Thanks for all help!

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#100399

On Mon, Dec 14, 2015 at 11:24 AM, KP <kai.peters@gmail.com> wrote:
> data = list(f.read(4))
> print data
>
> from a binary file might give
>
> ['\x10', '\x20', '\x12', '\x01']
>
>
> How can I receive this instead?
>
> [0x10, 0x20, 0x12, 0x01]
>
> Thanks for all help!

Try this:

data = [ord(x) for x in f.read(4)]

Note that it won't print out in hexadecimal.

>>> [0x10, 0x20, 0x12, 0x01]
[16, 32, 18, 1]

If you insist on that, try a subclass of int:

class ord(int):
    ord = ord
    def __new__(cls, x):
        return super().__new__(cls, cls.ord(x))
    def __repr__(self): return hex(self)

Then they'll come out in hex.

ChrisA

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#100405

On Sunday, 13 December 2015 16:33:20 UTC-8, Chris Angelico  wrote:
> On Mon, Dec 14, 2015 at 11:24 AM, KP <> wrote:
> > data = list(f.read(4))
> > print data
> >
> > from a binary file might give
> >
> > ['\x10', '\x20', '\x12', '\x01']
> >
> >
> > How can I receive this instead?
> >
> > [0x10, 0x20, 0x12, 0x01]
> >
> > Thanks for all help!
> 
> Try this:
> 
> data = [ord(x) for x in f.read(4)]
> 
> Note that it won't print out in hexadecimal.
> 
> >>> [0x10, 0x20, 0x12, 0x01]
> [16, 32, 18, 1]
> 
> If you insist on that, try a subclass of int:
> 
> class ord(int):
>     ord = ord
>     def __new__(cls, x):
>         return super().__new__(cls, cls.ord(x))
>     def __repr__(self): return hex(self)
> 
> Then they'll come out in hex.
> 
> ChrisA

Thanks much!

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#100410

On 12/13/2015 7:24 PM, KP wrote:
>
>
> data = list(f.read(4))
> print data
>
> from a binary file might give

In 2.x, a binary file and a text file are not distinguished.

> ['\x10', '\x20', '\x12', '\x01']

If a 'binary' file yields strings, you must be using 2.x.

> How can I receive this instead?
> [0x10, 0x20, 0x12, 0x01]

Use python 3.

-- 
Terry Jan Reedy

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#100413

On Mon, 14 Dec 2015 08:56 pm, Terry Reedy wrote:

> On 12/13/2015 7:24 PM, KP wrote:
>>
>>
>> data = list(f.read(4))
>> print data
>>
>> from a binary file might give
> 
> In 2.x, a binary file and a text file are not distinguished.

I think what you mean is that, in Python 2, reading from a file returns a
byte string regardless of whether you open it in text mode or binary mode.
That part is true, but there are other differences between text files and
binary files (opened in the correct mode): binary mode is guaranteed to
return the actual bytes in the file, but opening it in text mode may
perform some platform-specific processing:

(1) \r or \r\n may be converted to \n

(2) Ctrl-Z may be interpreted as end-of-file

There may be other changes made as well.


 
>> ['\x10', '\x20', '\x12', '\x01']
> 
> If a 'binary' file yields strings, you must be using 2.x.
> 
>> How can I receive this instead?
>> [0x10, 0x20, 0x12, 0x01]
> 
> Use python 3.

True, except by default integers display in decimal, not hex:

py> [0x10, 0x20, 0x12, 0x01]
[16, 32, 18, 1]



-- 
Steven

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