Variables in a loop, Newby question

[vanommen.robert]

Hello everyone, I have been away for a while.
I have been reading all the good advises and want to explain why I want to read the temperatures separately from the main script. It takes a long timeto read out 10 temperatures. About 10 seconds. So that’s the reason why I had the idea to create a separate script and I thought by making te variables Global I could access them by other scripts. Now I know that’s not the purpose of Global.
Maybe I can create a loop that keeps running simultaneously with the rest of the script.
I’ve downloaded a great student book about Python and learning a lot.
Thanks for all the answers and I’ll post more questions in the future, I’m sure of it.
Greetings Robert

 

[Dennis Lee Bieber]

Hello everyone, I have been away for a while.
I have been reading all the good advises and want to explain why I want to read the temperatures separately from the main script. It takes a long time to read out 10 temperatures. About 10 seconds. So that’s the reason why I had the idea to create a separate script and I thought by making te variables Global I could access them by

other scripts. Now I know that’s not the purpose of Global.

Maybe I can create a loop that keeps running simultaneously with the rest of the script.
I’ve downloaded a great student book about Python and learning a lot.
Thanks for all the answers and I’ll post more questions in the future, I’m sure of it.
Greetings Robert

Check the class threading.Thread, along with Queue.Queue -- presuming
the sensor reads are blocking calls, they should have minimal effect on the
main thread...

PSEUDO-code:
-=-=-=-=-
import threading
import Queue
import time

list_of_sensors = [ whatever, is, needed, to, access, each, sensor ]
#list of sensors may just be the ID strings, or if you need to open
#each, make it a list of the opened items, so the worker doesn't
#keep opening, reading, closing, for each sensor

tempQ = Queue.Queue()

def sensorWork(retQ, list_of_sensors):
while True:
for sensor in list_of_sensors:
temp = readSensor(sensor) #presumed to be blocking
retQ.put((sensor, temp, time.time())
#if a timestamp is useful

worker = threading.Thread(target=sensorWork,
args=(tempQ, list_of_sensors))
worker.setDaemon() #lets it die when the main program exits

worker.start()

#now do the main processing
while True:
#check for available temps
numTemps = tempQ.qsize() #should be good as only one consumer
if numTemps > 0:
for i in range(numTemps - 1):
#I'm not iterating over the queue as
#that might starve the main process
#if the sensor reads produce a reading
#just fast enough to keep up with
#this loop
(sensor, temp, timestamp) = tempQ.get()
#process the temp data
#here you do the rest of the main process, which should be
#something that returns here at some regular interval so that
#the loop checks for new temp readings to be processed

 

[vanommen.robert]

Op dinsdag 24 december 2013 17:23:43 UTC+1 schreef Jean-Michel Pichavant:

----- Original Message -----

Hello, for the first time I'm trying te create a little Python
program. (on a raspberri Pi)

I don't understand the handling of variables in a loop with Python.


Lets say i want something like this.

x = 1
while x <> 10
var x = x
x = x + 1

The results must be:

var1 = 1
var2 = 2

enz. until var9 = 9

How do i program this in python?

Short story, cause it's almost xmas eve :

python 2.5:

var = {}
for i in range(10):
var = i

print var[1]
print var[2]
print var

var here is a dictionary. I suggest that you read through the python tutorial

JM


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This was the information I was looking for and what my first question was about. Got this working, Thank you.