String error

[Kurta]

Hey there im not getting the expected result

i expect two numbers temperture and humidty seperated by a comma

here is my error:

line 25, in <module>
dataArray = arduinoString.split(",")

TypeError: a bytes-like object is required, not 'str'

my python code

import serial import numpy import matplotlib.pyplot as plt #from drawnow import arduinoData = serial.Serial('com3', 9600) while True: while (arduinoData.inWaiting() ==0): pass arduinoString = arduinoData.readline() dataArray = arduinoString.split(",") temp = float(dataArray[0]) humid = float(dataArray[1]) print (temp, ",", humid) 

what i Expected:

70 , 50

using python 3.7

[BashBedlam]

How are you initializing dataArray ?

arduinoString = '98.6, 89' dataArray = arduinoString.split(",") temp = float(dataArray[0]) humid = float(dataArray[1]) print (temp, ",", humid)

This code works because dataArray is an ordinary, run-of-the-mill python list and is not expecting a bytes like object.

[Serafim]

have you checked what kind of data you get on the serial port?

 arduinoString = arduinoData.readline() print(arduinoString) # check the output

[bowlofred]

When you have a regular string, you pass in another string object as text to split on.

>>> "split this, string, on the, commas".split(",") ['split this', ' string', ' on the', ' commas']

But if instead of a string you have a bytes object, this won't work.

>>> b"split this, string, on the, commas".split(",") Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: a bytes-like object is required, not 'str'

Your arduinoStringis a bytes object. So to split it, the argument has to be a bytes object as well. Instead of ",", use b"," OR convert it to a string and split it as normal.

>>> arduinoString = b"split this, string, on the, commas" >>> arduinoString.split(b",") # split directly on the bytes object [b'split this', b' string', b' on the', b' commas'] >>> arduinoString.decode().split(",") # decode to str, then split the str ['split this', ' string', ' on the', ' commas']

Note the result of the split is a list of bytes objects,

[snippsat]

serial.Serial will return bytes.
So in Python 3 can never mix str and bytes,two solution continue to work with bytes or convert to string decode().

Make error

>>> arduinoString = b'data,123' >>> arduinoString.split(",") Traceback (most recent call last): File "<interactive input>", line 1, in <module> TypeError: a bytes-like object is required, not 'str' 

Continue with bytes.

>>> arduinoString = b'data,123' >>> arduinoString.split(b",") [b'data', b'123']

Convert to str.

>>> arduinoString = b'data,123' >>> arduinoString = arduinoString.decode() >>> arduinoString 'data,123' >>> arduinoString.split(",") ['data', '123']

[Kurta]

have you checked what kind of data you get on the serial port?

 arduinoString = arduinoData.readline() print(arduinoString) # check the output

About the same thing,, i was down this path to begin with your correct this is a good place to start

this is what i got:
b'63,71\r\n'
i had a hunch it was a mismatch of data

[Kurta]

When you have a regular string, you pass in another string object as text to split on.

>>> "split this, string, on the, commas".split(",") ['split this', ' string', ' on the', ' commas']

But if instead of a string you have a bytes object, this won't work.

>>> b"split this, string, on the, commas".split(",") Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: a bytes-like object is required, not 'str'

Your arduinoStringis a bytes object. So to split it, the argument has to be a bytes object as well. Instead of ",", use b"," OR convert it to a string and split it as normal.

>>> arduinoString = b"split this, string, on the, commas" >>> arduinoString.split(b",") # split directly on the bytes object [b'split this', b' string', b' on the', b' commas'] >>> arduinoString.decode().split(",") # decode to str, then split the str ['split this', ' string', ' on the', ' commas']

Note the result of the split is a list of bytes objects,

This is actually what i needed and worked. i had convert to a number becuase the tutorial i was following next puts this inot a matplot chart and that was my goal cheers.

for any one else trying to do this here is the link ..Arduino-python to matplot
note i use Anaconda with python 3.7 this seems to work for me up to this point

[Kurta]

When you have a regular string, you pass in another string object as text to split on.

>>> "split this, string, on the, commas".split(",") ['split this', ' string', ' on the', ' commas']

But if instead of a string you have a bytes object, this won't work.

>>> b"split this, string, on the, commas".split(",") Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: a bytes-like object is required, not 'str'

Your arduinoStringis a bytes object. So to split it, the argument has to be a bytes object as well. Instead of ",", use b"," OR convert it to a string and split it as normal.

>>> arduinoString = b"split this, string, on the, commas" >>> arduinoString.split(b",") # split directly on the bytes object [b'split this', b' string', b' on the', b' commas'] >>> arduinoString.decode().split(",") # decode to str, then split the str ['split this', ' string', ' on the', ' commas']

Note the result of the split is a list of bytes objects,

This is actually what i needed and worked. I had convert to a number because the tutorial i was following.. puts this into a matplot chart and that was my goal.

for any one else trying to do this here is the link ..Arduino-python to matplot
Note: I use Anaconda with python 3.7 this seems to work for me up to this point. in the tutorial he uses 2.7.