Thanks to everyone, nice ideas! cheers
On Wed, Mar 3, 2010 at 10:02 AM, Christian Witts <cwi...@compuscan.co.za>wrote: > Jojo Mwebaze wrote: > >> Hi There, >> >> i would like to implement the following in lists >> >> assuming >> >> x = 3 >> y = 4 >> z = None >> >> i want to create a dynamic list such that >> >> mylist = [ x , y, z ] , if z in not None >> >> if z is None then >> >> mylist = [x,y] >> >> Anyhelp! >> >> cheers >> >> Jojo >> >> >> >> >> >> ------------------------------------------------------------------------ >> >> >> _______________________________________________ >> Tutor maillist - Tutor@python.org >> To unsubscribe or change subscription options: >> http://mail.python.org/mailman/listinfo/tutor >> >> > > <output function> | <variable> for <input set>, <predicate> > > So something like `x**2 for x in [1, 2, 3, 4, 5, None, 9] if x != None` > would iterate over your input set pumping the current item into the variable > x, it will check "if x != None" and if that condition evaluates true it will > perform the function you set out to perform. > > The predicate section acts as a filter to your data set ensuring the > variable you are working with meets certain conditions. If you wanted to > for eg. still accept the None but perform a different function on it Python > does allow it like `x**2 if x else 'Not a number' for x in [1, 2, 3, 4, 5, > None, 9]`. > > Hope that helps. > > -- > Kind Regards, > Christian Witts > > >
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