如何从字节转换为字符串？

Question

I am using OpenCV library in Python to detect faces and calculate the centre point of the rectangle(X,Y) formed around the face to control servos connected to an arduino. I converted it to bytes since python uses unicode, like this

data = "X{0:f}Y{1:f}".format(xx, yy)
bdata = b'data'
arduino.write(bdata)

I have to recieve these bytes in arduino program via serial communication, and it is receiving. The problem is i can't decode it back to string so the program can read I have tried and searched as much as on google read so many forums but nothing I am beginner in this as I have mechanical engg background so a total noob. I dont even know if this possible. thanks in advance!

Answer 1

bdata = b'data'

This is creating a string of four bytes, representing the characters d , a , t , a in ASCII encoding. That's probably not what you meant!

What you should do instead is encode the data string into bytes using the encode function. This requires that you think about the encoding; probably ASCII is fine for this situation, because you don't have any "special" characters:

bdata = data.encode('ascii')

As a general tip, it can be useful to experiment in the Python interpreter, for example:

>>> xx = 4.3
>>> yy = 7.1
>>> data = "X{0:f}Y{1:f}".format(xx, yy)
>>> bdata = b'data'
>>> bdata
b'data'
>>> bdata = data.encode('ascii')
>>> bdata
b'X4.300000Y7.100000'