Re: [Tutor] Python .decode issue
eryksun wrote: > On Tue, Feb 11, 2014 at 3:42 AM, Peter Otten <__pete...@web.de> wrote: >> >> Unfortunately the bytes --> bytes conversion codecs in Python 2 have no >> convenient analog in Python 3 yet. >> >> This will change in Python 3.4, where you can use >> > import codecs > codecs.decode(b"ff10", "hex") >> b'\xff\x10' > codecs.encode(b"\xff\x10", "hex") >> b'ff10' > > 3.4 restores the "hex" alias to encodings.aliases.aliases. You can use > "hex_codec" in earlier versions. > > >>> codecs.encode(b"\xff\x10", "hex_codec") > b'ff10' > >>> codecs.decode(b"ff10", "hex_codec") > b'\xff\x10' Thanks for the correction. >> But for now you are stuck with binascii.b2a_hex() etc. > > The alternate names are binascii.hexlify and binascii.unhexlify. > > >>> binascii.hexlify(b'\xff\x10') # b2a_hex > b'ff10' > >>> binascii.unhexlify(b'ff10') # a2b_hex > b'\xff\x10' ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python .decode issue
On Tue, Feb 11, 2014 at 3:42 AM, Peter Otten <__pete...@web.de> wrote: > > Unfortunately the bytes --> bytes conversion codecs in Python 2 have no > convenient analog in Python 3 yet. > > This will change in Python 3.4, where you can use > import codecs codecs.decode(b"ff10", "hex") > b'\xff\x10' codecs.encode(b"\xff\x10", "hex") > b'ff10' 3.4 restores the "hex" alias to encodings.aliases.aliases. You can use "hex_codec" in earlier versions. >>> codecs.encode(b"\xff\x10", "hex_codec") b'ff10' >>> codecs.decode(b"ff10", "hex_codec") b'\xff\x10' > But for now you are stuck with binascii.b2a_hex() etc. The alternate names are binascii.hexlify and binascii.unhexlify. >>> binascii.hexlify(b'\xff\x10') # b2a_hex b'ff10' >>> binascii.unhexlify(b'ff10') # a2b_hex b'\xff\x10' ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Python .decode issue
james campbell wrote:
> I have been currently trying to get a small piece of code to work, but
> keep getting an error:
>
> header_bin = header_hex.decode('hex')
> AttributeError: 'str' object has no attribute 'decode'
>
>
> The source of this code is from:
> https://en.bitcoin.it/wiki/Block_hashing_algorithm Here is the the code:
> >>> import hashlib >>> header_hex = ("0100" +
> "81cd02ab7e569e8bcd9317e2fe99f2de44d49ab2b8851ba4a308" +
> "e320b6c2fffc8d750423db8b1eb942ae710e951ed797f7affc8892b0f1fc122b" +
> "c7f5d74d" + "f2b9441a" + "42a14695") >>> header_bin =
> header_hex.decode('hex') >>> hash =
> hashlib.sha256(hashlib.sha256(header_bin).digest()).digest() >>>
> hash.encode('hex_codec')
> '1dbd981fe6985776b644b173a4d0385ddc1aa2a829688d1e' >>>
> hash[::-1].encode('hex_codec')
> '1e8d6829a8a21adc5d38d0a473b144b6765798e61f98bd1d'
>
> I get the above error when I input this line by line into Win7 IDLE 3.3.3.
> Hopefully somebody can point me in the right direction. Thanks.
With the move from Python 2 to Python 3 string handling was changed
py2 --> py3
-
str --> bytes
unicode --> str
Also the encode decode methods have changed.
bytes.decode() always gives you a str and str.encode() always returns bytes;
there are no bytes.encode or str.decode methods.
Unfortunately the bytes --> bytes conversion codecs in Python 2 have no
convenient analog in Python 3 yet.
This will change in Python 3.4, where you can use
>>> import codecs
>>> codecs.decode(b"ff10", "hex")
b'\xff\x10'
>>> codecs.encode(b"\xff\x10", "hex")
b'ff10'
But for now you are stuck with binascii.b2a_hex() etc.
Converting the 2x code of your example to 3x gives
>>> import hashlib
>>> import binascii
>>> header_hex = (
... b"0100"
... b"81cd02ab7e569e8bcd9317e2fe99f2de44d49ab2b8851ba4a308"
... b"e320b6c2fffc8d750423db8b1eb942ae710e951ed797f7affc8892b0f1fc122b"
... b"c7f5d74d"
... b"f2b9441a"
... b"42a14695")
>>> header_bin = binascii.a2b_hex(header_hex)
>>> hash = hashlib.sha256(hashlib.sha256(header_bin).digest()).digest()
>>> binascii.b2a_hex(hash)
b'1dbd981fe6985776b644b173a4d0385ddc1aa2a829688d1e'
>>> binascii.b2a_hex(hash[::-1])
b'1e8d6829a8a21adc5d38d0a473b144b6765798e61f98bd1d'
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Re: [Tutor] Python .decode issue
On 10/02/2014 23:16, Pierre Dagenais wrote:
On 14-02-08 12:55 AM, james campbell wrote:
header_bin = header_hex.decode('hex')
AttributeError: 'str' object has no attribute 'decode'
What I understand is that you are trying to decode 'hex', which is a
string. The interpreter is telling you that strings cannot be decoded.
I do not know header_hex.decode(), but I suspect it's expecting an hex
number, check it out.
PierreD.
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"AttributeError: 'str' object has no attribute 'decode'" is saying that
header_hex has no attribute decode, the string 'hex' doesn't enter into
the equation.
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Re: [Tutor] Python .decode issue
On 14-02-08 12:55 AM, james campbell wrote:
> header_bin = header_hex.decode('hex')
> AttributeError: 'str' object has no attribute 'decode'
What I understand is that you are trying to decode 'hex', which is a
string. The interpreter is telling you that strings cannot be decoded.
I do not know header_hex.decode(), but I suspect it's expecting an hex
number, check it out.
PierreD.
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Re: [Tutor] Python .decode issue
james campbell Wrote in message: > (Context lost because message was erroneously posted in html) strings cannot be decoded, so there's naturally no such method. Why not post a two line example of what you're trying, and explain what you were expecting it to do. -- DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Python .decode issue
I have been currently trying to get a small piece of code to work, but keep
getting an error:
header_bin = header_hex.decode('hex')
AttributeError: 'str' object has no attribute 'decode'
The source of this code is from:
https://en.bitcoin.it/wiki/Block_hashing_algorithm
Here is the the code:
>>> import hashlib >>> header_hex = ("0100" +
"81cd02ab7e569e8bcd9317e2fe99f2de44d49ab2b8851ba4a308" +
"e320b6c2fffc8d750423db8b1eb942ae710e951ed797f7affc8892b0f1fc122b" + "c7f5d74d"
+ "f2b9441a" + "42a14695") >>> header_bin = header_hex.decode('hex') >>> hash =
hashlib.sha256(hashlib.sha256(header_bin).digest()).digest() >>>
hash.encode('hex_codec')
'1dbd981fe6985776b644b173a4d0385ddc1aa2a829688d1e' >>>
hash[::-1].encode('hex_codec')
'1e8d6829a8a21adc5d38d0a473b144b6765798e61f98bd1d'
I get the above error when I input this line by line into Win7 IDLE 3.3.3.
Hopefully somebody can point me in the right direction. Thanks.
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