Best way to generate alternate toggling values in a loop?
khemkaamit at gmail.com
Thu Oct 18 13:11:48 CEST 2007
On 10/18/07, Carsten Haese <carsten at uniqsys.com> wrote:
> On Wed, 2007-10-17 at 23:55 +0000, Debajit Adhikary wrote:
> > I'm writing this little Python program which will pull values from a
> > database and generate some XHTML.
> > I'm generating a <table> where I would like the alternate <tr>'s to be
> > <tr class="Even">
> > and
> > <tr class="Odd">
> > What is the best way to do this?
> > I wrote a little generator (code snippet follows). Is there a better
> > (more "Pythonic") way to do this?
> > # Start of Code
> > def evenOdd():
> > values = ["Even", "Odd"]
> > state = 0
> > while True:
> > yield values[state]
> > state = (state + 1) % 2
> > # Snippet
> > trClass = evenOdd()
> > stringBuffer = cStringIO.StringIO()
> > for id, name in result:
> > stringBuffer.write('''
> > <tr class="%s">
> > <td>%d</td>
> > <td>%s</td>
> > </tr>
> > '''
> > %
> > (trClass.next(), id, name))
> This is a respectable first attempt, but I recommend you familiarize
> yourself with the itertools module. It has lots of useful tools for
> making your code more elegant and concise.
> Rather than spelling out the final result, I'll give you hints: Look at
> itertools.cycle and itertools.izip.
Why not just use enumerate ?
clvalues = ["Even", "Odd"]
for i, (id, name) in enumerate(result):
(clvalues[i % 2], id, name))
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