Need help clarifying my python script to run on Rpi3b+

Question

If it's not obvious, I'm trying to learn python, and am having a go at it. Although, I'm running into some issues. Any help would be appreciated.
I'm trying to run this on a Rpi3b+ & with a relay

Edit: What I'm trying to do is have the script check the water level first before the it activates the pump relay, but I can't even get the script to pass a debug run through. Or is there a better way to write this script that will work with a Rpi?

# Hydroponic Watering v.0.0.1
import RPi.GPIO as GPIO
import time
import sys
import signal
signal.signal(signal.sigint, GPIO)
# Setting GPIO pins on Rpi
GPIO.setmode(GPIO.BCM)
signal, resv_level_pin, GPIO.in, pull_up_down = GPIO.PUD_up = 18
pump_relay, GPIO.OUT = 9
def check_water_level
 if resv_level_pin == true
 pump_relay(on)
 elif resv_level_pin == false
 pump_relay(false)
 print("Water level too low!")
exit(sys.exit)

Debug output as follows:

Traceback (most recent call last):
 File "/usr/share/mu-editor/mu/mu-debug.py", line 4, in <module>
 from mu.app import debug
ModuleNotFoundError: No module named 'mu'
---------- FINISHED ----------
exit code: 1 status: 0

• Ghanima: I still wonder that any of this works. signal.signal(signal.sigint, GPIO) is certainly not what you intend it to be. What is signal, resv_level_pin, GPIO.in, pull_up_down = GPIO.PUD_up = 18 supposed to mean? Your function definition lacks the parentheses, the parameters (if any) and the colon. It is furthermore never called. if and elif lack the colon too and the indentation is off after if. Where there is the elif an else should suffice. True and False keywords should start uppercase.
• Ghanima: The final exit(sys.exit) is not only superfluous but also a strange combination of two things. See here. It should be exit() or sys.exit() with the parameter being the error code if you intend to send one to the caller.
• Milliways: The answer may have indicated your immediate problem, but the code listed still has code errors, logic errors and will actually do nothing. I suggest you look at GPIO Zero which has helpful tutorials.
• goldilocks: @hanlok Please understand that literally asking other people to write code for you ("is there a better way to write this script that will work") is kind of a non-starter. Based on the errors other people have pointed out, you need to get down to basics; if you don't understand those you will just have one error after another.

Answer 1

You're using Mu to run that python file, and it (not your script) is returning an error:

 File "/usr/share/mu-editor/mu/mu-debug.py", line 4, in <module>
 from mu.app import debug
ModuleNotFoundError: No module named 'mu'

I reccomend trying that code with Python IDLE, or Geany -- which should have come with Raspbian.

• user96931: @hanlok, if you have any further problems, don't hesitate to post 'em here.

Answer 2

After using a different editor, I learned that I had all kinds of problems, like not understanding what I was trying to accomplish, but after getting away from the screen and coming back with fresh eyes, I ended up with the follow script which works.

#!/usr/bin/env python3
# Hydroponic Watering v.0.0.1
import RPi.GPIO as GPIO
import time
import sys
import datetime
sys.stdout=open("test.txt","a")
timestamp = time.strftime("Time: %H:%M, Date: %Y%m%d, ")
# Setting GPIO pins on Rpi
GPIO.setwarnings(False)
switch1=18
pump_relay=26
refill_relay=21
GPIO.setmode(GPIO.BCM)
GPIO.setup(switch1,GPIO.OUT)
GPIO.setup(pump_relay, GPIO.OUT)
GPIO.setup(refill_relay, GPIO.OUT)
GPIO.output(switch1, GPIO.LOW)
# Check Water Level
switch1_is_on = GPIO.input(switch1)
# Activate pump_relay
if switch1_is_on:
 GPIO.output(26,1)
 time.sleep(5)
 print(timestamp,"Water level OK.")
 GPIO.output(26,0)
else:
 GPIO.output(21,1)
 time.sleep(5)
 GPIO.output(21,0)
 print(timestamp,"Water level is too low!")