Hello @JohnRennie sir :-)

Are you free?

I'm answering a question at the moment.

Okay sir

If you want to post your question I'll look at it as soon as I'm free.

developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

I want to do this in python. I have received a bytestream which I have stored in dvu using memory view dvu = memoryview(message). Now starting at a particular index, I want to read a 32 bit integer as in JS is done below:

dvu.getInt32(depthPosition, true)

Can't figure out how to do this

Not able to access the python chat room also due to less reputation :-(

Hi :-)

Are you trying to pass data from Javascript to Python?

No sir, trying to replicate that JS code in python

Ah, OK. Where is the data coming from? i.e. how is your Python program getting the data?

From a websocket

dvu = memoryview(message)

message comes from the websocket.

I now want to read a 32 bit integer starting from index 1, means dvu[1:5]

@Learner Does this help

@JohnRennie No sir, giving 0 for any input.

I need functions for even reading 8/16-bit integers and floats starting at a particular index.

I'd have to see code to comment. This isn't something I've done in Python.

Yes sir, sending, will take a few minutes.

message = b'?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x003s}D\xa8\x16fSZ\xa3\x07\x00\x01?\x16\x00\x00\x00\x9a\xa9~D\x9f5\x0f\x00\x00\x00\x00\x00\x00\x00\x00\x00f\xb6\x81D3s}D\x00\x00\x82D\x00\x00yD\xd7\xa3\xb0\xbf3fb\xc133\x85D\x00 \xeeC\x00…

Can you post a Python program that I can run to see what happens? I can't run the code about because I don't know what modules are needed.

Yes sir, you can run the above code after saving as python file.

All modules are inbuilt.

message = b'?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x003s}D\xa8\x16fSZ\xa3\x07\x00\x01?\x16\x00\x00\x00\x9a\xa9~D\x9f5\x0f\x00\x00\x00\x00\x00\x00\x00\x00\x00f\xb6\x81D3s}D\x00\x00\x82D\x00\x00yD\xd7\xa3\xb0\xbf3fb\xc133\x85D\x00 \xeeC\x00…

Yes sir, 63 is the correct output

means dvu.getint8 is same as data[0]

I don't know anything about memoryview in Python. I can try and Google it, but that will tale time and I'll have to do that later.

Sir is there any way I can post in the python chat room? I have to somehow do this before 3:30.

Do you have any questions or answers I can upvote?

Yes sir, I have one question but would it be ok to do so?

No-one is going to care :-)

But I can only upvote you one question i.e. add +10 to your rep. Will that be enough? I can't remember what rep you need to post in the chat.

Actually if you can post here I don't understand why you can't post in the Python chat ...

Ah, I had already upvoted that ...

@JohnRennie Yes sir, one would be ok. Stack overflow rating is 11 and here it is >20

@JohnRennie Possible on the answer?

@Learner Done!

Thank you very much sir :-) 🙏🙏

Can you do this?

D:\rhs\Python>python
Python 3.9.13 (tags/v3.9.13:6de2ca5, May 17 2022, 16:36:42) [MSC v.1929 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> message = b'?\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0…

@Learner Would that work for you?

@Learner This:

>>> a = 12345678
>>> b = a.to_bytes(a, "little")
>>> c = memoryview(b)
>>> c[0] + (c[1]<<8) + (c[2]<<16) + (c[3]<<24)
12345678

@JohnRennie Trying sir, just a minute

@JohnRennie It's working sir! :-)

Trying for others as well

And what if we want getFloat32?

print(struct.unpack('f', bytes(data[position:position+4])))

OK :-)

That probably works for int as well.

Yes sir, trying

Just had to use bytes() while unpacking

docs.python.org/3/library/struct.html

I think the struct module is the official way to do this sort of thing.

Yes sir

Any progress on the permutation question sir :-) ?

I won't be looking at the permutation question. It seems like it will take a lot of time and right now I'm pretty busy.

Ah no sir, just asking, I'll take a look at the solution now :-) It's already taken up a lot of time

Bye sir :-) Thank you very much 🙏

Bye :-)