Tips when starting Python programming V plotter in Raspberry

Two errors I encountered and How I googled them out of existence.

1.  Initially when importing numpy in python after installing it using python3 -m pip install numpy, i got error that "Importing numpy shared c extensions failed.". It got solved after running "sudo apt-get install libatlas-base-dev". Answer from " https://github.com/numpy/numpy/issues/16012"
2. While importing serial and running serial.Serial(), i got error that serial has nothing called Serial. Solution was to uninstall serial and install pyserial. Answer from "https://duckduckgo.com/?q=serial+has+no+attribute+serial&t=raspberrypi&ia=web"

pip uninstall serial

pip uninstall pyserial

pip install pyserial 

Working code in Raspbian 32 bit Os on Raspberry 4 B, with arduino cnc shield , 28BYJ motors for V plotter:

import numpy as np

import matplotlib

# ensure pyserial and serial is installed

import serial

import time

ser = serial.Serial("/dev/ttyUSB0")

ser.baudrate = 9600

# Existing steps per mm was 250 for x and y axis. It was found using $$ command.

# Measured actual travel of thread and set the $0 and $1 variable to correct values.

#$0 = 138.8 = 139 steps per mm

#$1 = 138.8 = 139 steps per mm

if (ser.is_open):

    print ("\n Serial port has been opened")

    print("\n Initialising communication with GRBL on the arduino")

    print("\n Using ")

    print(ser.name)

else:

    print("\n Could not open serial port for communicating with GRBL on the arduino")

# Communicating for codes

print("Stripping all end of characters for safety before encoding to byte string.")

ser.write("\r\n\r\n".strip().encode())

time.sleep(2);

ser.flushInput();

print("Using G01 command for a basic move command")

command= "G01X{}Y{}".format(10,10)

ser.write((command.strip()+'\n').encode());

#reading reply

grbl_reply = ser.readline().strip()

print("GRBL replied that")

print(grbl_reply)

time.sleep(4)

ser.flushInput();

print("\n Closing serial port ,finally.")        

ser.close();