I think mod1 is a lot easier to understand than %%. — John
On Apr 30, 2014, at 1:45 AM, Tomas Lycken <[email protected]> wrote: > Maybe... I really don't like the %% syntax, though - it's so cluttered. I > agree it makes sense, and maybe one can get used to it, but it does use a lot > of "ink". But I have no better suggestions :) > > // T > > On Monday, April 28, 2014 5:58:47 PM UTC+2, Stefan Karpinski wrote: > I wonder if this is important enough to warrant an operator. Something like > v[i%%n]? > > > On Mon, Apr 28, 2014 at 6:53 AM, Tim Holy <[email protected]> wrote: > There's mod1, if that helps. > > --Tim > > On Monday, April 28, 2014 02:57:09 AM Tomas Lycken wrote: > > In languages with zero-indexed vectors, I can easily let my indices "wrap" > > by taking a modulus: > > > > N = length(v) > > for i = 0:N-1 > > v[i+1 % N] = ... > > end > > > > will loop from the second element to the last, and then take the first, > > since N % N == 0. However, with Julia's 1-indexed arrays, it's not that > > easy - at some point, I'll end up at index 0: > > > > N = length(v) > > for i = 1:N > > v[i + 1 % N] = ... # breaks at i = N-1, since index then becomes 0 > > end > > > > I could first offset my entire loop index by one, take the modulus, and > > then add one again: > > > > N = length(v) > > for i = 0:N-1 > > v[(i+1 % N) + 1] = ... > > end > > > > but this seems clunky to me, and is difficult to understand at first glance > > (maybe not to current me, but to me-in-a-month trying to figure out what > > this code does...). Is there a more idiomatic way to do the same thing in > > Julia? > > > > My actual problem is having a (sorted) list of vertices in a polygon, and > > wanting to loop over the edges (i.e. adjacent pairs in the list), so in > > each step I want to access something like v[i+1]-v[i] and have the > > end-points close the loop. > > > > Thanks in advance, > > > > // T >
