First I wonder if these exists already somewhere, I was not able to find
exactly these in itertools module or somewhere else. (In case you find then
strange -- such iterators are needed for example when we have a set of points
in 2D and want to examine if the points build a convex polygon, so we have to
examine 3 consecutive points each, continuing from beginning for the last two.)
Better names or other suggestions welcome.
xpairs*[T](a: openarray[T]): array[2, T] {.inline.} =
var i, j: int
while i < len(a):
inc(j)
if j == a.len:
j = 0
yield [a[i], a[(j)]]
inc(i)
for xp in xpairs([1, 2, 3, 4, 5]):
echo xp
echo ""
iterator xclusters*[T](a: openarray[T]; s: static[int]): array[s, T]
{.inline.} =
var result: array[s, T] # iterators have no default result variable
var i = 0
while i < len(a):
for j, x in mpairs(result):
x = a[(i + j) mod len(a)]
yield result
inc(i)
for xp in xclusters([1, 2, 3, 4, 5], 2):
# echo xp
var u, v: int
(u, v) = xp # tuple unpacking works for arrays too!
echo u, ", ", v
echo ""
for xp in xclusters([1, 2, 3, 4, 5], 3):
echo xp
Run
