Error when using time with multiple conditions in Python

Question

The problem is, variable t1 is inside the loop, but I can't use it outside (because it's not defined); So the program returns "UnboundLocalError: local variable 't1' referenced before assignment". I don't know other ways to measure the time between this two events, each time the first starts (self explanatory with the code below).

if status in STATUSON:
        t1 = 0
        GPIO.output(17,GPIO.HIGH)
        time.sleep(0.5)
        GPIO.output(17,GPIO.LOW)
        return statement('Ok')
        t1 = time.time()
    elif status in STATUSOFF and time.time() - t1 >= 5:
        GPIO.output(17,GPIO.HIGH)
        time.sleep(0.5)
        GPIO.output(17,GPIO.LOW)
        return statement('Ok')
    elif status in STATUSOFF and time.time() - t1 <= 5:
        GPIO.output(17,GPIO.HIGH)
        time.sleep(0.5)
        GPIO.output(17,GPIO.LOW)
        time.sleep(2)
        GPIO.output(17,GPIO.HIGH)
        time.sleep(0.5)
        GPIO.output(17,GPIO.LOW)
        return statement('Ok')

I rolled back your last edit. Please add the solution in the answer space. We do not allow edits that add a solution in the question. — Dharman, Jan 20 '21 at 21:33

score 0 · Answer 1 · answered Jan 20 '21 at 16:56

0

Your problem is here:

        return statement('Ok')
        t1 = time.time()

You are returning before setting the t1 variable. Try reversing those 2 lines.

Also, as you're using return statement, I guess you're in a function, you should then return the t1 variable (maybe use a tuple?), or set it as a global variable (less recommended) to be able to do calculations in your main/top function.

answered Jan 20 '21 at 16:56

Gugu72

2,052
13
35

Thanks for the answer :). Yes, it's inside a function, but I need to get the time after the return of this first condition. I also, can't use tuples. – luis-gustta Jan 20 '21 at 17:03
@luis_gustta Could you share the whole function/script so I can better understand it? – Gugu72 Jan 20 '21 at 17:05
Hmm I'm not familiar with Flask and Flask_ask, sorry – Gugu72 Jan 20 '21 at 17:42

luis-gustta · Accepted Answer · 2021-01-22T16:22:33.223

Solved:

I've used pickle to solve the problem. It can convert Python objects to a character stream, and save it, so the next loop can access this data anytime (new code below).

    if status in STATUSON:
        t1 = time.time()
        with open('time.pickle', 'wb') as f:
            pickle.dump(t1, f)       
        GPIO.output(17,GPIO.HIGH)
        time.sleep(0.5)
        GPIO.output(17,GPIO.LOW)
        return statement('Ok')
    elif status in STATUSOFF:
        with open('time.pickle', 'rb') as f:
            t1 = pickle.load(f)        
        if time.time() - t1 >= 15:
            GPIO.output(17,GPIO.HIGH)
            time.sleep(0.5)
            GPIO.output(17,GPIO.LOW)
            open("time.pickle", "w").close()
            return statement('Ok')
        elif time.time() - t1 <= 15:
            GPIO.output(17,GPIO.HIGH)
            time.sleep(0.5)
            GPIO.output(17,GPIO.LOW)
            time.sleep(2)
            GPIO.output(17,GPIO.HIGH)
            time.sleep(0.5)
            GPIO.output(17,GPIO.LOW)
            return statement('Ok')
        else:
            GPIO.output(17,GPIO.HIGH)
            time.sleep(0.5)
            GPIO.output(17,GPIO.LOW)
            return statement('Ok')

Full codes: old, new

Error when using time with multiple conditions in Python

2 Answers2

Solved: