Re: Loop with else clause
Further to our discussion of how to improve a code review's discovery of the mistaken handling of a for...else... construct:- Yesterday was a national holiday, but today gave some opportunity to research. Way back in 2009 there was spirited discussion over on the Python Ideas list (warning, even the mailing list's index covers multiple screen-lengths): - this confusion is not new by any measure, herewith a list of previous occasions "fists were raised concerning for..else." https://mail.python.org/pipermail/python-ideas/2009-October/006164.html - an excellent summary of the 2009 debate which offers no less than six ways to 'improve' for... else... https://mail.python.org/pipermail/python-ideas/2009-October/006155.html - (as mentioned earlier) the BDFL weighed-in a couple of times. His regret is: "That's a flaw, and I don't quite know what to do about it. It's about 20 years too late to remove or rename it. But we probably should not do more of these. That's a lesson." (OK, so make that thirty years - older than the coder who the code-review noticed falling into this coding 'gotcha'!) https://mail.python.org/pipermail/python-ideas/2009-October/006083.html - herewith a (rather complicated) suggestion, and critique https://mail.python.org/pipermail/python-ideas/2009-October/006054.html - one rather hopeful option (actual words to be used notwithstanding) for i in SEQ: A except: B else: C appears here: https://mail.python.org/pipermail/python-ideas/2009-October/006044.html Somewhat related, PEP 548 proposed an "More Flexible Loop Control". This was addressing the confusion caused by break within a loop. It was rejected. Each of the above addresses issues 'within', that is to say happenings during iteration - whether the entire loop or iteration cut-short by a break (and thus the idea that "else" might be re-worded to indicate 'after a break'). However, as mentioned by one contributor, the specific use-case our team faced was an issue that arises prior to the loop. Alternately-expressed: that according to Python's logic, prevents even a single iteration of that loop. Thus, any 'solution' would reside outside of for and while statements because they only consider if a loop should continue or terminate - not handling the question of whether it should start at all! PEP 315 is the only discussion (I've found) which looks 'outside' or 'before' the loop itself. It proposed an "Enhanced While Loop", attempting to separate 'setup' or loop control from loop content. It was rejected. So, reading-around brought nothing much useful. Back to the code-face... Thank you to the several folk who responded with ideas to express/improve: if list: process_list() #the heading and for-loop, as above else: print( "Sorry... NB this is a constructed 'toy example' attempting to be the shortest illustration of use-cases and invented purely to communicate the need and structure. It was expected to be interpreted as pseudo-python-code. (you'd not use/allow "process_list" as the name of a function, would you?) (With apologies as necessary) one of the dangers of 'toy examples' is the reader taking them at face value, instead of as (over-)simplified illustrations. In 'real life' the loop code and the no-loop exception are both considerably longer than a single line. Accordingly, using a function would be a good way to summarise and self-document the activity, ie the if statement's two code-blocks would make the whole statement very/too-long (readability)! The "if list:" expression is overly-simplistic. The recommendation of "if len(list):" is absolutely sound, for reasons of polymorphism. In-lieu of a Python construct, there are definitely situations when use of a sentinel makes better sense. However, given their risk, in many ways Python tries to avoid using such, eg consuming iterators until a StopIteration exception is returned. (includes files, is subsumed by ContextManagers...), thus "pythonic". That said, the classic use of for... else... is in searching for a particular element within an iterable which has all the hallmarks of a "sentinel". Today, kicking ideas around, I coded three other possible 'solutions' for the review team's discussions: One of these involves coding three functions: the decision (yielding a boolean), the expected-case, and the unusual-case. The satisfaction in this was readability factors with a simple if statement.. Somewhat more complex, and I feel a bit OTT, was to sub-class list() and write a method which would indicate an empty list, plus include much of both the expected-case and the empty-list methods therein. Somehow "class ListShouldNotBeEmpty" doesn't seem a catchy (if descriptive) title - however, it works! The decision 'function' could also/then be made @property and (perhaps) thus contribute to readability. Lastly, I 'remembered' conditi
The sum of ten numbers inserted from the user
I thought something like it but doesn't work...
for n in range(1, 11):
x = input("Insert a number: ")
for y in range(x):
sum = y
print ("The sum is: ",y)
--
https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
On Thu, Feb 7, 2019 at 6:31 AM ^Bart wrote:
>
> I thought something like it but doesn't work...
>
> for n in range(1, 11):
> x = input("Insert a number: ")
The above, keeps replacing x with each input value. You don't want
that. Think about appending the input value to a list
>
> for y in range(x):
> sum = y
>
Here again you are replacing sum with each value of y. And think
further about what the value of y is for each iteration.
> print ("The sum is: ",y)
You should really be asking this sort of question in the python-tutor
mailing list. You should also use print function in your loops to
learn what is really going on.
> --
> https://mail.python.org/mailman/listinfo/python-list
--
Joel Goldstick
http://joelgoldstick.com/blog
http://cc-baseballstats.info/stats/birthdays
--
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timezones
I made a small script to practise with timezones:
#!/usr/bin/env python3
# -*- coding: utf_8 -*-
from datetime import datetime, timedelta
from pytz import timezone
import pytz
amsterdam_datetime = datetime(2018, 12, 17, 11, 31, 26,
tzinfo=timezone('Europe/Amsterdam'))
print(amsterdam_datetime)
utc_datetime = amsterdam_datetime.astimezone(pytz.utc)
print(utc_datetime)
amsterdam_datetime = datetime(2018, 6, 17, 11, 31, 26,
tzinfo=timezone('Europe/Amsterdam'))
print(amsterdam_datetime)
utc_datetime = amsterdam_datetime.astimezone(pytz.utc)
print(utc_datetime)
The output of the script is:
2018-12-17 11:31:26+00:20
2018-12-17 11:11:26+00:00
2018-06-17 11:31:26+00:20
2018-06-17 11:11:26+00:00
I respected:
2018-12-17 11:31:26+01:00
2018-12-17 10:31:26+00:00
2018-06-17 11:31:26+02:00
2018-06-17 09:31:26+00:00
I need this functionality for adjusting wrong timestamps in Android
JPG-images as the 'Exif.GPSInfo.GPSTimeStamp' and
'Exif.GPSInfo.GPSDateStamp' are missing.
Why I get this unrespected results?
Kind regards,
Jaap.
--
Jaap van Wingerde
e-mail: 1234567...@vanwingerde.nl
--
https://mail.python.org/mailman/listinfo/python-list
Re: Implement C's Switch in Python 3 [OT languages]
Am 05.02.19 um 02:20 schrieb DL Neil: So, even with the French making their dates into sentences, not a single one uses ordinals! - did the computer people in all these languages/cultures decide that the more numeric approach was better/easier/... (ie simpler/less-complex) :) For the two languages I know well, German (mother tongue) and Czech (studied for 5 years, 1 year abroad in Prague) I can assure you that the numeric ordinals were not dicated by the computer people, but that's been the typographic tradition since ever. You write the number with a period, also for dates. In regular sentences, something like "he achieved the eigth placement in a tournament" it depends on the size of the number, below ten or twelve one usually spells it out (with inflection and everything) and above it's typically written with numbers and a period. But I read a funny story at the Czech language instutute's page about the influence of MS Word on Czech spelling. In dates, the name of the month is written in lowercase "1. prosince". Howver, MS Word thinks that the period is a full-stop which starts a new sentence, and it autocorrects it to "1. Prosince". This has happened so often that they brought it up as a special topic, that this autocorrection is wrong. Not even the convention/use of title-case is consistent! Title case? In German, there are intricate rules about the capitalization in regular sentences; there is no such thing as title case. Only very rarely ALL CAPS are used. Have a good sleep ;) Christian -- https://mail.python.org/mailman/listinfo/python-list
RE: timezones
I'd say if the documentation mentions it, but doesn't say why, then we're not
gonna be able to do much better for you as far as "why" goes.
http://pytz.sourceforge.net/
"Unfortunately using the tzinfo argument of the standard datetime constructors
"does not work" with pytz for many timezones."
But it looks like they suggest something along the lines of...
timezone('Europe/Amsterdam').localize(datetime(2018, 12, 17, 11, 31, 26))
>From the examples on http://pytz.sourceforge.net/#problems-with-localtime ...
>>> eastern = timezone('US/Eastern')
>>> fmt = '%Y-%m-%d %H:%M:%S %Z%z'
>>> loc_dt = datetime(2002, 10, 27, 1, 30, 00)
>>> est_dt = eastern.localize(loc_dt, is_dst=True)
>>> edt_dt = eastern.localize(loc_dt, is_dst=False)
>>> print(est_dt.strftime(fmt) + ' / ' + edt_dt.strftime(fmt))
2002-10-27 01:30:00 EDT-0400 / 2002-10-27 01:30:00 EST-0500
Browse through their examples and see if you can find something similar that
works for you.
-Original Message-
From: Python-list
[mailto:python-list-bounces+david.raymond=tomtom@python.org] On Behalf Of
Jaap van Wingerde
Sent: Wednesday, February 06, 2019 9:27 AM
To: python-list@python.org
Subject: timezones
I made a small script to practise with timezones:
#!/usr/bin/env python3
# -*- coding: utf_8 -*-
from datetime import datetime, timedelta
from pytz import timezone
import pytz
amsterdam_datetime = datetime(2018, 12, 17, 11, 31, 26,
tzinfo=timezone('Europe/Amsterdam'))
print(amsterdam_datetime)
utc_datetime = amsterdam_datetime.astimezone(pytz.utc)
print(utc_datetime)
amsterdam_datetime = datetime(2018, 6, 17, 11, 31, 26,
tzinfo=timezone('Europe/Amsterdam'))
print(amsterdam_datetime)
utc_datetime = amsterdam_datetime.astimezone(pytz.utc)
print(utc_datetime)
The output of the script is:
2018-12-17 11:31:26+00:20
2018-12-17 11:11:26+00:00
2018-06-17 11:31:26+00:20
2018-06-17 11:11:26+00:00
I respected:
2018-12-17 11:31:26+01:00
2018-12-17 10:31:26+00:00
2018-06-17 11:31:26+02:00
2018-06-17 09:31:26+00:00
I need this functionality for adjusting wrong timestamps in Android
JPG-images as the 'Exif.GPSInfo.GPSTimeStamp' and
'Exif.GPSInfo.GPSDateStamp' are missing.
Why I get this unrespected results?
Kind regards,
Jaap.
--
Jaap van Wingerde
e-mail: 1234567...@vanwingerde.nl
--
https://mail.python.org/mailman/listinfo/python-list
--
https://mail.python.org/mailman/listinfo/python-list
RE: The sum of ten numbers inserted from the user
Well of course that doesn't work. For starters, x is an int or a float value.
After the loop It holds the 10th value. It might hold 432.7 ... It is not a
list.
The default start for range is 0. The stop value, as you already know, is not
part of the range. So I will use range(10).
In the second loop, I think you thought x would be a list and you I'm sure you
wanted to do
for y in x:
but instead you did
for y in range(x)
and remember x might be a very large number.So the second loop would loop
that many times, and each pass it would assign y (which has first value of 0
and last value of whatever x-1 is) to sum. Even though its name is "sum" it is
not a sum. After the loop it would hold x-1. You wanted to do sum += y.
Or sum = sum + y. I prefer the former, but that could reflect my history as a
C and C++ programmer.
And then you printed y, but you really want to print sum (assuming that sum
was actually the sum).
Putting all of the above together, you want to do this:
vallist =[] # an empty list, so we can append to it
for n in range(10):
x = input("Insert a number: ")# get 1 number into x
vallist.append(x) # append it to our list
# Now vallist holds 10 values
sum = 0 # No need to start sum as a float, in Python if we add a float to an
integer the result will be float. It doesn't matter in the program if sum is
int or float.
for y in vallist:
sum += y
print( "The sum is: ", sum)
-Original Message-
From: ^Bart
Sent: Thursday, February 7, 2019 6:30 AM
To: python-list@python.org
Subject: The sum of ten numbers inserted from the user
I thought something like it but doesn't work...
for n in range(1, 11):
x = input("Insert a number: ")
for y in range(x):
sum = y
print ("The sum is: ",y)
--
https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
This is my whack at it, I can't wait to hear about it being the wrong big o
notation!
numbers=[]
while len(numbers) < 10:
try:
chip = int(input('please enter an integer: '))
except ValueError:
print('that is not a number, try again')
else:
numbers.append(chip)
print(sum(numbers))
On Thu, Feb 7, 2019 at 10:23 AM Schachner, Joseph <
joseph.schach...@teledyne.com> wrote:
> Well of course that doesn't work. For starters, x is an int or a float
> value. After the loop It holds the 10th value. It might hold 432.7 ...
> It is not a list.
> The default start for range is 0. The stop value, as you already know, is
> not part of the range. So I will use range(10).
>
> In the second loop, I think you thought x would be a list and you I'm sure
> you wanted to do
> for y in x:
> but instead you did
> for y in range(x)
> and remember x might be a very large number.So the second loop would
> loop that many times, and each pass it would assign y (which has first
> value of 0 and last value of whatever x-1 is) to sum. Even though its name
> is "sum" it is not a sum. After the loop it would hold x-1. You wanted to
> do sum += y.Or sum = sum + y. I prefer the former, but that could
> reflect my history as a C and C++ programmer.
>
> And then you printed y, but you really want to print sum (assuming that
> sum was actually the sum).
>
> Putting all of the above together, you want to do this:
>
> vallist =[] # an empty list, so we can append to it
> for n in range(10):
> x = input("Insert a number: ")# get 1 number into x
> vallist.append(x) # append it to our list
>
> # Now vallist holds 10 values
>
> sum = 0 # No need to start sum as a float, in Python if we add a float
> to an integer the result will be float. It doesn't matter in the program if
> sum is int or float.
> for y in vallist:
> sum += y
>
> print( "The sum is: ", sum)
>
>
>
> -Original Message-
> From: ^Bart
> Sent: Thursday, February 7, 2019 6:30 AM
> To: python-list@python.org
> Subject: The sum of ten numbers inserted from the user
>
> I thought something like it but doesn't work...
>
> for n in range(1, 11):
> x = input("Insert a number: ")
>
> for y in range(x):
> sum = y
>
> print ("The sum is: ",y)
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>
--
https://mail.python.org/mailman/listinfo/python-list
RE: The sum of ten numbers inserted from the user
I just realized that input has changed in Python 3 and I was using Python
2.7.13 with from __future__ import print_function and some others, but not that.
In Python 3 the int( ) or float( ) cast is necessary because input( ) does what
raw_input( ) did in Python 2; raw_input( ) name is therefore removed.
--- Joe S.
From: Ian Clark
Sent: Thursday, February 7, 2019 1:27 PM
To: Schachner, Joseph
Cc: python-list@python.org
Subject: Re: The sum of ten numbers inserted from the user
This is my whack at it, I can't wait to hear about it being the wrong big o
notation!
numbers=[]
while len(numbers) < 10:
try:
chip = int(input('please enter an integer: '))
except ValueError:
print('that is not a number, try again')
else:
numbers.append(chip)
print(sum(numbers))
On Thu, Feb 7, 2019 at 10:23 AM Schachner, Joseph
mailto:joseph.schach...@teledyne.com>> wrote:
Well of course that doesn't work. For starters, x is an int or a float value.
After the loop It holds the 10th value. It might hold 432.7 ... It is not a
list.
The default start for range is 0. The stop value, as you already know, is not
part of the range. So I will use range(10).
In the second loop, I think you thought x would be a list and you I'm sure you
wanted to do
for y in x:
but instead you did
for y in range(x)
and remember x might be a very large number.So the second loop would loop
that many times, and each pass it would assign y (which has first value of 0
and last value of whatever x-1 is) to sum. Even though its name is "sum" it is
not a sum. After the loop it would hold x-1. You wanted to do sum += y.
Or sum = sum + y. I prefer the former, but that could reflect my history as a
C and C++ programmer.
And then you printed y, but you really want to print sum (assuming that sum
was actually the sum).
Putting all of the above together, you want to do this:
vallist =[] # an empty list, so we can append to it
for n in range(10):
x = input("Insert a number: ")# get 1 number into x
vallist.append(x) # append it to our list
# Now vallist holds 10 values
sum = 0 # No need to start sum as a float, in Python if we add a float to an
integer the result will be float. It doesn't matter in the program if sum is
int or float.
for y in vallist:
sum += y
print( "The sum is: ", sum)
-Original Message-
From: ^Bart mailto:gabriele1nos...@hotmail.com>>
Sent: Thursday, February 7, 2019 6:30 AM
To: python-list@python.org
Subject: The sum of ten numbers inserted from the user
I thought something like it but doesn't work...
for n in range(1, 11):
x = input("Insert a number: ")
for y in range(x):
sum = y
print ("The sum is: ",y)
--
https://mail.python.org/mailman/listinfo/python-list
--
https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
Ian Clark writes:
> This is my whack at it, I can't wait to hear about it being the wrong big o
> notation!
>
> numbers=[]
>
> while len(numbers) < 10:
> try:
> chip = int(input('please enter an integer: '))
> except ValueError:
> print('that is not a number, try again')
> else:
> numbers.append(chip)
>
> print(sum(numbers))
Why would you not keep a running total, rather than list of the numbers?
I've not been following assiduously, so maybe I missed some other
requirement...
--
Ben.
--
https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
On 2019-02-07, Ben Bacarisse wrote:
> Ian Clark writes:
>
>> This is my whack at it, I can't wait to hear about it being the wrong big o
>> notation!
>>
>> numbers=[]
>>
>> while len(numbers) < 10:
>> try:
>> chip = int(input('please enter an integer: '))
>> except ValueError:
>> print('that is not a number, try again')
>> else:
>> numbers.append(chip)
>>
>> print(sum(numbers))
>
> Why would you not keep a running total, rather than list of the numbers?
> I've not been following assiduously, so maybe I missed some other
> requirement...
Because you think it likely that tomorrow the marketing people are
going to say "oh, and we want to know the min, max, mode, median,
standard deviation, and count of odd vs. even.
OTOH, they may instead say, "Oh, it's not 10 numbers, it's 10 million
numbers."
--
Grant Edwards grant.b.edwardsYow! I selected E5 ... but
at I didn't hear "Sam the Sham
gmail.comand the Pharoahs"!
--
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Re: Python program to phone?
On 2/4/19 3:20 PM, Steve wrote: I have written my first python program (600 lines!) to help control my blood sugar and it has been so successful that my A1c dropped form 9.3 to an impressive 6.4. It will be much more useful if I had it on my phone. (MotoG, Android) The .py file reads/writes to two txt files. About a year ago, I installed Kivy and managed to transfer the "Hello World" app to my phone and it worked. I am not on a different computer and believe that I got all the way through the installation but I do not see how to invoke it. I am sure that I can go through the tutorial again and use my program instead. How do I figure out what is wrong and might there ne a better way to get the program onto my phone? Steve P.S. Yes, I tried to post this about two weeks ago but could not seem to respond to the replies I received. I could contact one or two individuals but apparently not the masses. How do I find out how this list works? Foornote: There's 99 bugs in the code, in the code. 99 bugs in the code. Take one down and patch it all around. Now there's 117 bugs in the code. Steve I'm not sure but I think there is an Android lib for py that is available to help convert your app to a mobile platform. Also, if you're of a mind, I'd love to see the code you wrote for blood sugar. I need to lower my A1C as well and could use all the help I can get. Regards Jack -- https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
Bart writes:
> On 07/02/2019 20:45, Ben Bacarisse wrote:
>> Ian Clark writes:
>>
>>> This is my whack at it, I can't wait to hear about it being the wrong big o
>>> notation!
>>>
>>> numbers=[]
>>>
>>> while len(numbers) < 10:
>>> try:
>>> chip = int(input('please enter an integer: '))
>>> except ValueError:
>>> print('that is not a number, try again')
>>> else:
>>> numbers.append(chip)
>>>
>>> print(sum(numbers))
>>
>> Why would you not keep a running total, rather than list of the numbers?
>> I've not been following assiduously, so maybe I missed some other
>> requirement...
>
> Because it separates the two tasks: (A) capture N values; (B) perform
> some operation on those values, in this case summing (and taking
> advantage here of the built-in sum()).
Sure. Did I miss some hint that this program might need to be more
flexible like that? It looks like a beginners' exercise.
If the purpose is to be flexible, why is an array the right option rather
than, say, accumulating a value over an iterable? You need some idea of
the future direction or what the exercise is intended to reinforce.
--
Ben.
--
https://mail.python.org/mailman/listinfo/python-list
Re: The sum of ten numbers inserted from the user
Grant Edwards writes:
> On 2019-02-07, Ben Bacarisse wrote:
>> Ian Clark writes:
>>
>>> This is my whack at it, I can't wait to hear about it being the wrong big o
>>> notation!
>>>
>>> numbers=[]
>>>
>>> while len(numbers) < 10:
>>> try:
>>> chip = int(input('please enter an integer: '))
>>> except ValueError:
>>> print('that is not a number, try again')
>>> else:
>>> numbers.append(chip)
>>>
>>> print(sum(numbers))
>>
>> Why would you not keep a running total, rather than list of the numbers?
>> I've not been following assiduously, so maybe I missed some other
>> requirement...
>
> Because you think it likely that tomorrow the marketing people are
> going to say "oh, and we want to know the min, max, mode, median,
> standard deviation, and count of odd vs. even.
>
> OTOH, they may instead say, "Oh, it's not 10 numbers, it's 10 million
> numbers."
Sure. I can think of reasons for all sorts of designs. Has there been
any hint? It looks like a beginners' exercise with little extra to go
on.
--
Ben.
--
https://mail.python.org/mailman/listinfo/python-list
RE: Python program to phone?
BeeWare looks as if it requires Java, does it? Is it exclusively java? = Footnote: Zamboni locks up after running into large patch of loose teeth. -Original Message- From: Python-list On Behalf Of Mario R. Osorio Sent: Tuesday, February 5, 2019 8:58 AM To: python-list@python.org Subject: Re: Python program to phone? Hi there Steve. Did you check BeeWare? (https://pybee.org/) -- https://mail.python.org/mailman/listinfo/python-list -- https://mail.python.org/mailman/listinfo/python-list
Re: Python program to phone?
On 02/07/2019 09:00 PM, Steve wrote: > BeeWare looks as if it requires Java, does it? > Is it exclusively java? Kind of. You do your coding in Python, then that's compiled to python byte code, which is then translated to Java byte code. You'll need the Android SDK, even if you're not using Java directly. Unfortunately Google no longer lets you download just the SDK by itself. Instead you have to download the entire 1GB Android Studio. I haven't done anything with PyBee, but it looks promising for your purposes. Instead of using text files, you'll probably need to use sqlite data stores. Not a huge deal if PyBee abstracts this for you. Recently I made an android app using V-play.net, which is built on QtQuick. Basically it was all javascript. This might work for your app also. It's not Python, but the learning curve isn't huge. It took me far longer to figure out the GUI layout than it did to figure out the Javascript. -- https://mail.python.org/mailman/listinfo/python-list
how to exit from a nested loop in python
for i in range(len(A.hp)): for j in range(len(run_parameters.bits_Mod)): req_slots[j] = math.ceil((A.T[i]) for g in Temp[i]["Available_ranges"][j]: for s in range(g[0], g[-1]): if (s+req_slots[j]-1) <= g[-1]: if (Temp[i]['cost'][j] <= (run_parameters.PSD): -- When this condition is true i want to break the nested loop and start from the begining served_count +=1 A.T[i]["First_index"]= s A.T[i]["Last_index"]= s+req_slots[j]-1 A.T[i]["Status"]= 1 A.T[i]["Selected_MOD"] = j break I have this code. When the last "if" condition is satisfied, i want to break all the loops and start the nested loop for next i. else, the loop should continue. can anyone help me? -- https://mail.python.org/mailman/listinfo/python-list
