Replicating byte string creation done in Javascript into Python 2.7

Question

I have a function I am mapping from Javascript:

var commandBytes = [4,1,0,0,0,0, Math.floor(224 + (52/16)), 52 % 16];

...this is how I have in Python:

data = bytearray([4,1,0,0,0,0, 224 + 52 // 16, 52 % 16])

...this is what the output looks like in IDLE:

bytearray(b'\x04\x01\x00\x00\x00\x00\xe3\x04')

...this is what the original output looks like when output by Javascript to the Command Prompt window:

<Buffer 04 01 00 00 00 00 e3 04>

...first issue I have is the bytes in IDLE seem to be printed in hex rather than actual numbers. Second is, even though I know my connection to the machine I am passing the command to is good as I am getting a response, the command itself does not work.

What do I need to change so that my Python output replicates my Javascript output?

Thanks

Why do you care how it is displayed on your terminal - it looks like it has equivalent data. If you really want it to display the same then extend the bytearray() and implement your own __str__() and/or __repr__(). You haven't provided enough information to help with why the command isn't working. — AChampion
– AChampion, Commented May 26, 2018 at 19:42
What exactly are you trying to replicate? What are "actual numbers"? Why is formatting and issue? I don't really understand your question here. — juanpa.arrivillaga
– juanpa.arrivillaga, Commented May 26, 2018 at 19:57

AChampion · Accepted Answer · 2018-05-26 20:18:04Z

1

You can easily change how it is printed, either by creating your own print_function or by extending bytearray and implementing __str__() and/or __repr__(), e.g.:

class ByteArray(bytearray):
    def __str__(self):
        return '<Buffer {}>'.format(' '.join(format(x, '02x') for x in self))

In []:
b = ByteArray([4,1,0,0,0,0, 224 + 52 // 16, 52 % 16])
print(b)

Out[]:
<Buffer 04 01 00 00 00 00 e3 04>

edited May 26, 2018 at 20:18

answered May 26, 2018 at 19:42

AChampion

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