Partial seems useful, thank you. The Lambda solutions also work. But what IS lambda anyway? I don't see that its doing anything other than being syntactic verbose.
On Apr 9, 7:24 am, Jason Grout <jason-s...@creativetrax.com> wrote: > On 4/8/11 2:00 PM, John H Palmieri wrote: > > > > > > > On Friday, April 8, 2011 11:03:14 AM UTC-7, ObsessiveMathsFreak wrote: > > > I have a python type function taking two variables is defined in such > > a say that accidental evaluation is a possibility. Here is a > > simplified version > > > def h(x,n): > > if x>2: > > return n-x > > else: > > return n*x-2 > > > How can functions like this be plotted over x for a constant value of > > n in sage? > > > sage: plot(lambda x: h(x,3), (x, 0, 4)) > > > works for me. > > Another approach that supplies default arguments for the *first* > variables is to use functools.partial: > > def h(x,n): > if x>2: > return n-x > else: > return n*x-2 > from functools import partial > plot(partial(h,1),(n,-1,1)) > > This effectively plots h(1,n), where n goes from -1 to 1. > > Note that we can't do > > plot(partial(h,x=1),(n,-1,1)) > > since plot calls the function by positional arguments, rather than > keyword arguments (i.e., this last plot calls h like this: > h(-.5434344,x=1), and so we get two values for x). I think this is a > bug; I think if the variable is specified in the plot range, the > function should be called with a keyword argument, so that the function > would be called as h(n=-.5434344,x=1). I believe I even have a patch > from late last year somewhere on my laptop that changes this behavior to > call a function using keyword arguments if the variable is specified in > the plot range. Once this bug is fixed, then doing plot(partial(h,x=1), > (n,-1,1)) would work. > > Thanks, > > Jason -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
