Python How to allocate and restrict memory space to an array containing data?

Question

I am required to transmit a BYTE array containing hexadecimal values of size no more than 250 bytes in the following format:

header|no of data structures|Data/Payload

Now, I have read multiple posts on stackoverflow regarding memory allocation to a an array but i didn't reach any viable solution. I am required to restrict the data to 250 bytes as i am going to be sending this data to a device that reads only 250 bytes.

Currently the size of my array according to python is 416 bytes.

Do you mean a list, array (from use array), a numpy array, or a bytearray? — cdarke
– cdarke, Commented Jun 8, 2016 at 7:08
Please edit your question to make that clear. Compression is data dependant. Have you looked at struct.pack()? — cdarke
– cdarke, Commented Jun 8, 2016 at 7:18

lotrgandalf · Accepted Answer · 2016-08-02 06:19:44Z

2

Declaring a byte array of size 250 makes a byte array that is equal to 250 bytes, however python's memory management is programmed in such a way that it acquires more space for an integer or a character as compared to C or other languages where you can assign an integer to be short or long. The sys.getsizeof() command ,as another user pointed out ,represents the internal representation of your data structure and not the actual size of the data when it is transmitted to another device.

data= bytearray(b'\x00'*length)

The size in bytes of the byte array is determined by the length. For example if one needs to send data of n bytes then length will be equal to n. I verified it by checking the size of the data received on the receiver's end.

answered Aug 2, 2016 at 6:19

lotrgandalf

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Community · Accepted Answer · 2017-05-23 10:28:46Z

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sys.getsizeof(newdata) is returning the internal representation of your data structure, and is system dependent. Refer to sys — System-specific parameters and functions

Try this link: How many bytes does a string have

edited May 23, 2017 at 10:28

CommunityBot

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answered Jun 8, 2016 at 8:21

M Hart

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1 Comment

lotrgandalf Over a year ago

Do you think that the size of data determined by the python script will affect the data being received by the device?. Is there a possibility that python is determining more bytes than required? and it wouldn't be an issue once the data is transmitted

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