[Tutor] Why does loop duplicate?
Intent is to print "Jack, Kack, " with "O" and "Q" delivering a longer suffix. Instead, I get the printout shown with duplicates and a second deviation with "O" and "Q" as shown. Why? IDLE and Shell are Python 2.5.4 running on Windows 8.1. prefixes = 'JKLMNOPQ' ###FAILS WITH REPEATS suffix = 'ack' suffixb= 'uack' for letter in prefixes: if letter == "O": print letter + suffixb if letter == "Q": print letter + suffixb else: print letter + suffix >>> Jack Jack Kack Kack Lack Lack Mack Mack Nack Nack Ouack Oack Oack Pack Pack Quack Qack >>> Thanks, Ken Hammer ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Why does loop duplicate?
On 16/12/2015 19:37, Ken Hammer wrote:
Intent is to print "Jack, Kack, " with "O" and "Q" delivering a longer suffix. Instead, I get
the printout shown with duplicates and a second deviation with "O" and "Q" as shown.
Why?
That's what you've told the code to do :)
prefixes = 'JKLMNOPQ' ###FAILS WITH REPEATS
### OH NO IT DOESN'T - nothing personal but it's pantomine season in the
UK :)
suffix = 'ack'
suffixb= 'uack'
for letter in prefixes:
if letter == "O":
print letter + suffixb
if letter == "Q":
print letter + suffixb
else:
print letter + suffix
You test for "O", but then follow with a test for "Q" and an else
clause. You could write :-
elif letter == "Q"
but the cleanest way of doing this is:-
for letter in prefixes:
if letter in ("O", "Q"):
print letter + suffixb
else:
print letter + suffix
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
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Re: [Tutor] Why does loop duplicate?
On Wed, Dec 16, 2015 at 02:37:18PM -0500, Ken Hammer wrote:
> Intent is to print "Jack, Kack, " with "O" and "Q" delivering a
> longer suffix. Instead, I get the printout shown with duplicates and
> a second deviation with "O" and "Q" as shown. Why?
Are you absolutely sure about that? When I run your code, I don't get
any duplicates:
prefixes = 'JKLMNOPQ' ###FAILS WITH REPEATS
suffix = 'ack'
suffixb= 'uack'
for letter in prefixes:
if letter == "O":
print letter + suffixb
if letter == "Q":
print letter + suffixb
else:
print letter + suffix
Output is:
Jack
Kack
Lack
Mack
Nack
Ouack
Oack
Pack
Quack
If you are getting duplicate lines, you must be running code that is
different from the code you posted to us. We cannot help you with code
we can't see.
As far as the code shown, look carefully at the code inside the
for-loop:
if letter == "O":
print letter + suffixb
if letter == "Q":
print letter + suffixb
else:
print letter + suffix
The first test checks to see if the letter is "O", and if so, it prints
"Ouack". Then, *regardless* of whether it just printed "Ouack" or not,
it then does a second test, for "Q". Since Q is not O, it then prints
"Oack".
No other letter gets treated that way.
Instead, you should change the second "if" to an "elif" (else if). Or
better still:
if letter == "O" or letter == "Q":
print letter + suffixb
else:
print letter + suffix
which can be simplified even more to:
if letter in ("O", "Q"):
print letter + suffixb
else:
print letter + suffix
--
Steve
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Re: [Tutor] interface
On Mon, Dec 14, 2015 at 10:08 PM, Alex Kleider wrote: > Thank you, gentlemen (Alan, Ben, Mark,) for your advice. > The consensus seems to be in favour of tkinter > so I'll head in that direction. If you are into books, "Programming Python, 4th ed." by Mark Lutz, has an extensive section on tkinter (Alan had pointed this out to me, and I have found Lutz's coverage very helpful). Plus the book (very thick!) has lots of other goodies. Also, the now old book, "Python and Tkinter Programming" by John E. Grayson is just about Tkinter (with a capital "T") as it is copyrighted 2000. Despite this I think it is still quite useful even if you are working in Python 3 as, as far as I can tell, t/Tkinter has not changed substantially in how the coding goes. -- boB ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
