[Tutor] Help with building bytearray arrays

[Alan Gauld]

On 08/09/18 03:15, Chip Wachob wrote:

> my function's main pieces are:

It would probably be better to post the entire function,
a partial code sample like this just gives us an inkling
of what you are trying to do but not enough to be sure
of where the errors lie.

> def transfer_byte_array():
>    MAX_LOOP_COUNT = 64
>    slice_size = 16
>    read_ary = bytearray(MAX_LOOP_COUNT)
>    scratch_ary = bytearray()
> 
>    for step in range (0, MAX_LOOP_COUNT, slice_size):
>       scratch_ary = transfer(data_to_send, slice_size)

You pass in two arguments here but in your description
of transfer below it is a method of an object that
only takes one (self being the object). Something is
broken here.

I would expect, given the code below, to see something
like
        scratch_ary = someObject.transfer(data_to_send)

>       for bytes in range (0, slice_size):
>          read_ary = scratch_ary[bytes]

This is replacing rad_ary each time with a single value from scratch_ary.
At the end of theloop read_ary wil;l cpontain the last valuye in
scratch_ary. You can achieve the same result without a loop:

raed_ary = scratch_ary[-1]

But I suspect that's not what you want.
I think what you really want is the first
slice_size elements of scratch_ary:

read_ary = scratch_ary[:slice_size]   # use slicing

> Ideally, I'd like to take the slice_size chunks that have been read
> and concatenate them back togetjer into a long MAX_LOOP_COUNT size
> array to pass back to the rest of my code.  Eg:

You need to create a list of read_ary

results = []

then after creating each read_ary value append it
to results.

results.append(read_ary)

Then, at the very end, return the summation of all
the lists in results.

return sum(results,[])

>     def transfer(self, data):

The self parameter indicates that this is a method
definition from a class. That implies that to use
it you must create an instance of the class and
call the method on that instance.

HTH

-- 
Alan G
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