Anyone into Python? I have a few questions relating to nested loops

Thanks

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Re: Python
By: Mortifis to All on Sun Dec 09 2018 01:40 pm

Anyone into Python? I have a few questions relating to nested loops

I've done a bit of Python for work.

Nightfox

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Re: Python
By: Mortifis to All on Sun Dec 09 2018 01:40 pm

Anyone into Python? I have a few questions relating to nested loops

Ask away. I'm curious what your question is.

The Dawn of Demise BBS (tdod.org)

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Re: Python
By: Mortifis to All on Sun Dec 09 2018 01:40 pm

Anyone into Python? I have a few questions relating to nested loops

I've done a bit of Python for work.

Seems Python is very finicky about use of proper indentation :/ I am (trying) to code some random light sequences for use with my Raspberry Pi, mostly works, however, when I try to set a while ... for ... try while ... blah blah blah it complains about indentation. when I remove the first x = 0 ... while x < cycle: x = x + 1 it seems to work correctly.

here is my spaghetti code:

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import random
import mutagen.mp3
import sys

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

# init list with pin numbers
seq0 = [2, 3, 4, 17, 27, 22, 10, 9] # RPI GPIO PINS
seq1 = [3, 17, 22, 9]
seq2 = [2, 4, 27, 10]
seq3 = [2, 9, 3, 10, 4, 22, 17, 27, 27, 17, 22, 4, 10, 3, 9, 2]

from random import randint
rand = random.randint(0, 3)

mP3 = sys.argv[1]

from mutagen.mp3 import MP3
audio = MP3(mP3)
cycle = int(audio.info.length)
print ' Playing ', mP3, ' for ', cycle, 'seconds'

if mP3 == "letitgo.mp3":
rand = 1 # speeds timing up
SleepTimeS = 0.2
SleepTimeL = 0.1
else:
SleepTimeS = 1.2 # normal speed
SleepTimeL = 0.2

if rand == 0: seq = seq0
if rand == 1: seq = seq1
if rand == 2: seq = seq2
if rand == 3: seq = seq3

x = 0
while x < cycle:
x = x + 1

for i in seq:
GPIO.setup(i, GPIO.OUT)
GPIO.output(i, GPIO.HIGH)

# main loop

try:
while True:

for i in seq:
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeL);

except KeyboardInterrupt:
print " Quit"

GPIO.cleanup()

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Re: Python
By: Mortifis to All on Sun Dec 09 2018 01:40 pm

Anyone into Python? I have a few questions relating to nested loops

Ask away. I'm curious what your question is.

My question is about indentation and nested loops ... seems at times I get syntax error as well (x += 1) . I can paste the code if you are a good reader :-P the code I pasted to Nightfox works except that it does loop through the while x < cycle: as a main counter.

What is need is a counter so that the GPIO pins blink only for the length of an mp3 then automagically shutdown when the song is over

In the code I pasted to Nightfox the lights blink until ^C is hit

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Re: Re: Python
By: Mortifis to Minex on Mon Dec 10 2018 11:37:55

What is need is a counter so that the GPIO pins blink only for the length of an mp3 then automagically shutdown when the song is over

What value does audio.info.length represent? Duration of the song in seconds / milliseconds / something else? File size?

I doubt if a counter is the right way to go. Seems like you could store the start time prior to entering the loop, and then make your While condition something like 'current_time - start_time < song_duration', so that the loop breaks once that amount of time has passed.

In the code I pasted to Nightfox the lights blink until ^C is hit

As expected, I assume.

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Re: Python
By: Mortifis to All on Sun Dec 09 2018 01:40 pm

Anyone into Python? I have a few questions relating to nested loops

I've done a bit of Python for work.

I appreciate you looking in this for me, I think I figured out the correct loop usage I need, python is soooo F$%&'n finicky -;P:

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import random
import mutagen.mp3
import sys

GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

# init list with pin numbers
seq0 = [2, 3, 4, 17, 27, 22, 10, 9] # RPI GPIO PINS
seq1 = [3, 17, 22, 9]
seq2 = [2, 4, 27, 10]
seq3 = [2, 9, 3, 10, 4, 22, 17, 27, 27, 17, 22, 4, 10, 3, 9, 2]

from random import randint
rand = random.randint(0, 3)

mP3 = sys.argv[1]

from mutagen.mp3 import MP3
audio = MP3(mP3)
cycle = int(audio.info.length)
print ' Playing ', mP3, ' for ', cycle, 'seconds'

if mP3 == "letitgo.mp3":
rand = 1 # speeds timing up
SleepTimeS = 0.2
SleepTimeL = 0.1
else:
SleepTimeS = 1.2 # normal speed
SleepTimeL = 0.2

if rand == 0: seq = seq0
if rand == 1: seq = seq1
if rand == 2: seq = seq2
if rand == 3: seq = seq3

x = 0
while x < cycle:
x = x + 1

for i in seq:
GPIO.setup(i, GPIO.OUT)
GPIO.output(i, GPIO.HIGH)

# main loop

try:
while True and x < cycle:

for i in seq:
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeL);
# 4 seconds to cycle loop
x = int(x + ((SleepTimeS + SleepTimeL) * 3))

except KeyboardInterrupt:
print " Quit"

GPIO.cleanup()

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Re: Re: Python
By: Mortifis to Minex on Mon Dec 10 2018 11:37:55

What is need is a counter so that the GPIO pins blink only for the length of an mp3 then automagically shutdown when the song is over

What value does audio.info.length represent? Duration of the song in seconds / milliseconds / something else? File size?

yes, audo.info.length is the time of the mp3 in seconds, int(audio.info.length) makes it a whole number

I doubt if a counter is the right way to go. Seems like you could store the start time prior to entering the loop, and then make your While condition something like 'current_time - start_time < song_duration', so that the loop breaks once that amount of time has passed.

isn't that just a counter of sorts as well? I discover the error of my ways, I was putting an unnecessary while: ahead of everything, the easy-for-me solution to self-terminate when the song finished playing was

mP3 = sys.argv[1]

from mutagen.mp3 import MP3
audio = MP3(mP3)
cycle = int(audio.info.length)

x = 0

for i in seq:
GPIO.setup(i, GPIO.OUT)
GPIO.output(i, GPIO.HIGH)
seq.reverse()

try:
while True and x < cycle:

for i in seq:
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.LOW)
time.sleep(SleepTimeS);
GPIO.output(i, GPIO.HIGH)
time.sleep(SleepTimeL);
# 4 seconds to cycle loop
x = int(x + ((SleepTimeS + SleepTimeL) * 3.5))

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Re: Re: Python
By: Mortifis to echicken on Mon Dec 10 2018 15:13:06

isn't that just a counter of sorts as well?

Sure, as much as any clock is a counter incrementing with the passage of time. I don't mean that "using a counter" is inherently bad, just that there's a more straightforward approach that also lets you ditch a magic number.

Doesn't matter, you'll achieve the same result in the end.

---
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Re: Re: Python
By: Mortifis to Nightfox on Mon Dec 10 2018 12:16 pm

I appreciate you looking in this for me, I think I figured out the correct loop usage I need, python is soooo F$%&'n finicky -;P:

Good to hear you may have figured it out.

Yeah, Python has strict rules about indentation. Instead of using curly braces to mark blocks of code like other languages, all the lines in a block of code in Python must be indented the same way (same number of spaces or tabs).

Nightfox

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Re: Re: Python
By: Mortifis to echicken on Mon Dec 10 2018 15:13:06

isn't that just a counter of sorts as well?

Sure, as much as any clock is a counter incrementing with

the passage of

time. I don't mean that "using a counter" is inherently

bad, just that

there's a more straightforward approach that also lets you

ditch a magic

number.

Doesn't matter, you'll achieve the same result in the end.

I prefer straightforward approaches, I just started looking
at Python and am not very familiar with the structure and
functions.

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Re: Re: Python
By: Mortifis to Nightfox on Mon Dec 10 2018 12:16 pm

I appreciate you looking in this for me, I think I

figured out the

correct loop usage I need, python is soooo F$%&'n

finicky -;P:

Good to hear you may have figured it out.

Yeah, Python has strict rules about indentation. Instead

of using curly

braces to mark blocks of code like other languages, all the

lines in a block

of code in Python must be indented the same way (same

number of spaces or

tabs).

So much for being a lazy spaghetti coder with python lol

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Re: Re: Python
By: Nightfox to Mortifis on Mon Dec 10 2018 07:13 pm

Yeah, Python has strict rules about indentation. Instead of using curly braces to mark blocks of code like other languages, all the lines in a block of code in Python must be indented the same way (same number of spaces or tabs).

This is something I love about Python, personally.

Make sure you don't mix spaces and tabs for indentation in your code, or Python will likely complain.

--Josh

////--------------------------------------------------
BiC -=- http://breakintochat.com -=- bbs wiki and blog

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Re: Re: Python
By: Kirkman to Nightfox on Tue Dec 11 2018 09:26 pm

This is something I love about Python, personally.

Make sure you don't mix spaces and tabs for indentation in your code, or Python will likely complain.

I like that it helps keep code consistent, but one downside that bugs me is that text editors often assume you want to continue your indented code block in Python, and Python doesn't use curly braces, which text editors often use with other languages to know when you're done with a code block. In other languages, text editors can even know you're done with a one-line block of code without curly braces since that's how other programming languages work.

Nightfox

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Re: Re: Python
By: Kirkman to Nightfox on Tue Dec 11 2018 09:26 pm

This is something I love about Python, personally.

Make sure you don't mix spaces and tabs for indentation in your code, or Python will likely complain.

I like that it helps keep code consistent, but one downside that bugs me is that text editors often assume you want to continue your indented code block in Python, and Python doesn't use curly braces, which text editors often use with other languages to know when you're done with a code block. In other languages, text editors can even know you're done with a one-line block of code without curly braces since that's how other programming languages work.

I keep running into unexpected indent or unexpected unindent when using nested loops and such, which is obviously my lack of understanding of Python. Another problem I keep running into is, for example, x = x + 1 or x += 1 ... syntax error. I won't paste my troubled code but Python is definitely a finicky language

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I keep running into unexpected indent or unexpected unindent when using nested loops and such, which is obviously my lack of understanding of Python. Another problem I keep running into is, for example, x = x + 1 or x += 1 ... syntax error. I won't paste my troubled code but Python is definitely a finicky language

I don't know what you're using for an editor, but it's not working for you. NotePad++, Visual Studio Code, PyCharm, and Sublime Text will all help with syntax, formatting, and beautification. You will most likely need to install plugins to make them work with python code, but a good editor always helps.

Fireball

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