Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.mixmin.net!hq-usenetpeers.eweka.nl!hq-usenetpeers.eweka.nl!xlned.com!feeder3.xlned.com!newsfeed.xs4all.nl!newsfeed2a.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.006 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; '"this': 0.03; 'else:': 0.03; 'syntax': 0.04; 'result,': 0.07; 'function,': 0.09; 'logic': 0.09; 'python': 0.11; 'def': 0.12; 'itself.': 0.14; 'books': 0.15; 'count,': 0.16; 'excludes': 0.16; 'itself).': 0.16; 'python),': 0.16; 'requested.': 0.16; 'true:': 0.16; 'wrote:': 0.18; '(not': 0.18; 'library': 0.18; '(the': 0.22; 'input': 0.22; 'to:name :python-list@python.org': 0.22; 'print': 0.22; '(a)': 0.24; "haven't": 0.24; 'header:In-Reply-To:1': 0.27; 'feature': 0.29; 'am,': 0.29; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'code': 0.31; 'default,': 0.31; 'extract': 0.31; 'factor': 0.31; 'sep': 0.31; 'run': 0.32; 'another': 0.32; 'fri,': 0.33; 'received:74.125.82': 0.34; 'but': 0.35; 'received:google.com': 0.35; 'false': 0.36; 'doing': 0.36; 'url:org': 0.36; 'skip:& 10': 0.38; 'to:addr:python-list': 0.38; 'received:74.125': 0.39; 'heard': 0.39; 'to:addr:python.org': 0.39; 'how': 0.40; 'problems.': 0.60; 'then,': 0.60; 'break': 0.61; 'new': 0.61; 'advanced': 0.63; 'relatively': 0.65; 'prime': 0.74; 'completion': 0.78; 'code):': 0.84; 'divide': 0.84; 'received:74.125.82.172': 0.84; 'url:2014': 0.84; 'url:16': 0.93 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; bh=cnmNwb/h0TMeV2jpnagL384dflLNeVZSyLdQ6l9Pub4=; b=I4qksZpO0vHMPxsir7THOYRLZtfWf98jRI3ovKmwSCKqPVhYuUC0MTgSwI8iZU52UR tJI42Np+Sfgpxm3bk2LYxgjA7n2N7TDj5+7A/75tKhvvCTe9wW0tTFWuhdkANyBT1Oh3 j4RmXIB2RcyCl+bei3mdcn4W3dgKDvuaU2yIAqLPox/L+G8BqaRxyND5IIryZ/8C6Gc4 YTKFOsIAO1PpXUAcb2NrC0DrFIHps1kYNNq7MPTSt4jQmlZAGOu6fI2Bo+ZKIW78mOrN j6Z71NXNXKn1u4OSfEMx1l+mr08YaYQ/XVQkauB/p9rqoWAi/UiRdonCxKznUnD/SLA4 aWeQ== X-Gm-Message-State: ALoCoQnjCZ9rey5kPeoTsoeuoeVqfuyINSX+7lP2d08y/mUrB4hfkuV9P47AwNTH9c2lwtBttW2x X-Received: by 10.194.202.231 with SMTP id kl7mr4865523wjc.134.1409936965476; Fri, 05 Sep 2014 10:09:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1enj0att6bkrnvb81rhma5dbuk3h28agl8@4ax.com> References: <1enj0att6bkrnvb81rhma5dbuk3h28agl8@4ax.com> From: Chris Kaynor Date: Fri, 5 Sep 2014 10:09:05 -0700 Subject: Re: My backwards logic To: "python-list@python.org" Content-Type: multipart/alternative; boundary=047d7bae4836fbb7ce05025487f2 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 139 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1409936972 news.xs4all.nl 2890 [2001:888:2000:d::a6]:38801 X-Complaints-To: abuse@xs4all.nl X-Received-Bytes: 9693 X-Received-Body-CRC: 2556174981 Xref: csiph.com comp.lang.python:77596 --047d7bae4836fbb7ce05025487f2 Content-Type: text/plain; charset=UTF-8 On Fri, Sep 5, 2014 at 9:48 AM, Seymore4Head wrote: > I'm still doing practice problems. I haven't heard from the library > on any of the books I have requested. > > > http://www.practicepython.org/exercise/2014/04/16/11-check-primality-functions.html > > This is not a hard problem, but it got me to thinking a little. A > prime number will divide by one and itself. When setting up this > loop, if I start at 2 instead of 1, that automatically excludes one of > the factors. Then, by default, Python goes "to" the chosen count and > not "through" the count, so just the syntax causes Python to rule out > the other factor (the number itself). > > So this works: > while True: > a=random.randrange(1,8) > print (a) > for x in range(2,a): > if a%x==0: > print ("Number is not prime") > break > wait = input (" "*40 + "Wait") > > But, what this instructions want printed is "This is a prime number" > So how to I use this code logic NOT print (not prime) and have the > logic print "This number is prime" > > One neat feature of Python is the for...else function. The code inside the else block will run only if the loop ran to completion (untested code follows): while True: a=random.randrange(1,8) print (a) for x in range(2,a): if a%x==0: print ("Number is not prime") break else: print("Number is prime") wait = input (" "*40 + "Wait") Depending on how advanced you want to get (I know you are relatively new to Python), another decent way would be to extract the prime check to a function, and return the result, and print based on that result (again, untested code): def isPrime(number): for x in range(2,a): if a%x==0: return False return True while True: a=random.randrange(1,8) print (a) if isPrime(a): print("Number is prime") else: print("Number is not prime") wait = input (" "*40 + "Wait") --047d7bae4836fbb7ce05025487f2 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On F= ri, Sep 5, 2014 at 9:48 AM, Seymore4Head <Seymore4Head@hotmail.= invalid> wrote:
I'm still doing pract= ice problems.=C2=A0 I haven't heard from the library
on any of the books I have requested.

http://www.practicepython.org/exerci= se/2014/04/16/11-check-primality-functions.html

This is not a hard problem, but it got me to thinking a little.=C2=A0 A
prime number will divide by one and itself.=C2=A0 When setting up this
loop, if I start at 2 instead of 1, that automatically excludes one of
the factors.=C2=A0 Then, by default, Python goes "to" the chosen = count and
not "through" the count, so just the syntax causes Python to rule= out
the other factor (the number itself).

So this works:
while True:
=C2=A0 =C2=A0 a=3Drandom.randrange(1,8)
=C2=A0 =C2=A0 print (a)
=C2=A0 =C2=A0 for x in range(2,a):
=C2=A0 =C2=A0 =C2=A0 =C2=A0 if a%x=3D=3D0:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 print ("Number is not prime&= quot;)
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 break
=C2=A0 =C2=A0 wait =3D input (" "*40=C2=A0 + "Wait")
But, what this instructions want printed is "This is a prime number&qu= ot;
So how to I use this code logic NOT print (not prime) and have the
logic print "This number is prime"


One neat f= eature of Python is the for...else function. The code inside the else block= will run only if the loop ran to completion (untested code follows):
=

while True:
=C2=A0 =C2=A0 a=3Drandom.randrange(1,8)<= br>=C2=A0 =C2=A0 print (a)
=C2=A0 =C2=A0 for x in range(2,a):
=C2=A0 = =C2=A0 =C2=A0 =C2=A0 if a%x=3D=3D0:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 print ("Number is not prime")
=C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 break
=C2=A0 =C2=A0 else:
=C2=A0 =C2= =A0 =C2=A0 =C2=A0 print("Number is prime")
=C2=A0 =C2=A0 wait = =3D input (" "*40=C2=A0 + "Wait")


Depending on how advanced you want to get (I know yo= u are relatively new to Python), another decent way would be to extract the= prime check to a function, and return the result, and print based on that = result (again, untested code):

def isPrime(number)= :
=C2=A0 =C2=A0 for x in range(2,a):
=C2=A0 =C2=A0 =C2=A0= =C2=A0 if a%x=3D=3D0:
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return = False
=C2=A0 =C2=A0 return True

wh= ile True:
=C2=A0 =C2=A0 a=3Drandom.randrange(1,8)
=C2=A0= =C2=A0 print (a)
=C2=A0 =C2=A0 if isPrime(= a):
=C2=A0 =C2=A0 =C2=A0 =C2=A0 print("= ;Number is prime")
=C2=A0 =C2=A0 else:=
=C2=A0 =C2=A0 =C2=A0 =C2=A0 print("Nu= mber is not prime")
=C2=A0 =C2=A0 wait =3D input (" "*4= 0=C2=A0 + "Wait")

<= /div> --047d7bae4836fbb7ce05025487f2--