Using min and max to limit values to a range in Python

Question

I have this small python file that I wrote in Python 2.7.9 and now I am testing it in Python 3.4.3.

All works, for I am able to send commands to my RPI. But when I send the command to change the volume on the speaker (ranging 1-100), they are all read by the python script as 100%.

Example:

Volume 26, is seen as Volume 100. I add commented out the line with volume = ... and it works now but I can not prevent people from spamming the volume to the max @ 100%.

Code:

def setVolume(volume):
    volume = max(60, min(30, volume)) #Volume Spam Protection
    sendPost(speakerAddress+"volume","<volume>"+str(volume)+"</volume>")

What does this have to do with "# Representation" at all? Do you mean "number representation"? The relationship of the title to the content is unclear. — Charles Duffy, Aug 17 '15 at 15:57
#=Number, so the title, Odd Python Number Representation. Sorry for the confusion though. — TheAce, Aug 17 '15 at 16:42
If there's something odd about how numbers are represented, surely you can find an easier way to ask about that, isolating it in a way that doesn't involve logic around min and max? — Charles Duffy, Aug 17 '15 at 16:43
...which is to say: I still don't see any part of this question (or its answers) that revolves around representation. — Charles Duffy, Aug 17 '15 at 18:24

score 4 · Accepted Answer · answered Aug 17 '15 at 15:54

I am guessing when you say volume 26 is seen as 100% , you mean it comes as 60 .

That is because of the line -

max(60, min(30, volume))

This roughly translates to , minimum between 30 and volume, and maximum between volume and 60 , so you would always get 60 , since if volume is greater than 30, you would get 30 from the inner min() , and from outer max() you would get 60. You can think what would happen for volume less than 30.

You actually want to do -

volume = min(60, max(30, volume))

I am not sure how this would have been working in Python 2.7 , according to the above condition the issue should have been there for Python 2.7 as well.

score 4 · Answer 2 · answered Aug 17 '15 at 15:58

4

Much more readable would be to not use min and max at all; they are efficient for find the extrema of an arbitrary number of arguments, but overkill for only two.

if volume < 30:
    volume = 30
elif volume > 60:
    volume = 60

(This would have the side effect of fixing any logic errors resulting from the nested construction you were using.)

answered Aug 17 '15 at 15:58

chepner

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Chepner, are saying the code should be this instead: def setVolume(volume): if volume < 30: volume = 30 elif volume > 60: volume = 60 sendPost(speakerAddress+"volume",""+str(volume)+"") – TheAce Aug 17 '15 at 17:32
Yes, I would recommend that. – chepner Aug 17 '15 at 17:33
I will try them both out and report back :D – TheAce Aug 17 '15 at 17:34

score 1 · Answer 3 · answered Aug 17 '15 at 15:55

I guess, what you really want is that your volume is in the range 30..60. In this case you should swap you min/max line to this:

volume = min(60, max(30, volume))

So you get the maximum of the volume and 30 -- (at least 30) -- and the minimum of that result and 60 -- maximum 60.

score 0 · Answer 4 · answered Sep 07 '22 at 21:14

0

I have written a well readable function limit for that purpose:

def limit(iMin, iVal, iMax):
   return min(iMax, max(iMin, iVal))

volume = limit(30, volume, 60)

answered Sep 07 '22 at 21:14

Michael Hutter

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Using min and max to limit values to a range in Python

Example:

Code:

4 Answers4