[Tutor] Adding line numbers to a Python Script
I quote this example (and the problem that I am facing trying to understand) from the book "Beginning Python - From Novice to Professional" by Magnus Lie Hetland Page 227 # numberlines.py import fileinput(1) for line in fileinput.input(inplace = true)(2) line = line.rstrip()(3) num=fileinput.lineno()..(4) print '%-40s #%2i' %(line,num).(5) Question: Please help me understand: Line (3) - Are we stripping the entire line of code first, inserting the code at the end (line (5)) and then placing it back at the same place ? Line (5) - What does the individual characters in the expression "Print '%-40s #%2i' %(line,num)" mean ? - '-40s' : is this the space [what does "-40s" mean] that we are creating post - which the line nos is inserted "#%2i" ? - What does '%2" mean ? - Is that 2 cursor spaces of width ? Much thanks in advance... -- Thanks and regards, Sudip Bhattacharya Mobile: +91 100 706 Home Land line: +91 11 22237561 Office Land line: +91 0124 4321078 eMail ID: sud...@sudipb.com; sud...@gmail.com Please visit my website at: www.sudipb.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Tuple - Immutable ?
>>> s=(1,2,3) >>> s=s+(4,5,6) >>>s (1,2,3,4,5,6) The tuple has changed. I thought I read that tuples are sequences (like lists), but they are immutable - They can't be changed once created. Could someone explain please ? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Tuple - Immutable ?
That makes perfect sense. What happened was that the old tuple got replaced with a new tuple (old + new items) and NOT changed cause tuple is immutable. Thanks HTH. On Thu, Mar 8, 2012 at 4:53 PM, col speed wrote: > On 8 March 2012 18:11, Sudip Bhattacharya wrote: > >>>> s=(1,2,3) > >>>> s=s+(4,5,6) > >>>>s > > (1,2,3,4,5,6) > > > > The tuple has changed. > > > > I thought I read that tuples are sequences (like lists), but they are > > immutable - They can't be changed once created. Could someone explain > please > > ? > > I'm just a noob, but as nobody else has replied yet.. > As far as I *think* I know: > s=s+(4,5,6) creates a new tuple, it doesn't change it. > Tuples are immutable as in you can't add or append and stuff. > Also: > > >>> s[0] = 8 > Traceback (most recent call last): > File "", line 1, in > TypeError: 'tuple' object does not support item assignment > Nor does it have attribute "reverse" or anything like that. > > HTH > Col > -- Thanks and regards, Sudip Bhattacharya Mobile: +91 100 706 Home Land line: +91 11 22237561 Office Land line: +91 0124 4321078 eMail ID: sud...@sudipb.com; sud...@gmail.com Please visit my website at: www.sudipb.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
