Python convert string repr of byte data into float data

Question

I have 12 bytes being sent over a web socket used to represent 3 float values. The other program does this:

float m_floatArray[3]; 
...
Serial.write((byte*) m_floatArray, 12); //12 b/c 3 floats at 4 bytes each

The data I receive in my python program looks like this:

#the data is printed from: received = ser.read(12)  
received = '\xe4C\x82\xbd-\xe4-\xbe&\x00\x12\xc0'

I want to essentially do this in my python program:

x = getFirstFloat(received)
y = getSecondFloat(received)
z = getThirdFloat(received)

How can I parse my data?

This is not c it's AFAIK a specialized language for arduino, similar to c++. — Iharob Al Asimi
– Iharob Al Asimi, Commented Jan 6, 2016 at 0:02
Don't hardcode the size, use sizeof(m_floatArray) instead of 12. — Iharob Al Asimi
– Iharob Al Asimi, Commented Jan 6, 2016 at 0:06
@iharob the code you're commenting on is obviously only for demonstration purposes, you should be concentrating on the Python part. — Mark Ransom
– Mark Ransom, Commented Jan 6, 2016 at 0:18

Chad S. · Accepted Answer · 2016-01-06 00:40:01Z

2

A short example:

>>> a,b,c = [random.random()*10 for i in range(3)]
>>> a
0.9446191909332258
>>> b
7.578277797297625
>>> c
8.061585451293366
>>> recieved = struct.pack('fff', a, b, c)
>>> recieved
'\x90\xd2q?@\x81\xf2@A\xfc\x00A'
>>> x,y,z = struct.unpack('fff', recieved)
>>> x
0.9446191787719727
>>> a
0.9446191909332258
>>> b
7.578277797297625
>>> y
7.578277587890625
>>> c
8.061585451293366
>>> z
8.061585426330566
>>>

Note that you may want to specify the byte order in the format string

answered Jan 6, 2016 at 0:40

Chad S.

6,66918 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Python convert string repr of byte data into float data

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related