All Combinations
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All Combinations

Given this list
List(’A’, ‘B’, ‘C’, ‘D’)
, return this result:

[A][B][C][D]
[AB][AC][AD][BC][BD][CD]
[ABC][ABD][ACD][BCD]
[ABCD]


This is how one might implement it in python. I got this from the python itertools package, but I didn’t manage to convert it to Coda language. Index incrementing (
the highlighted purple part
) proved difficult.
def
combinations(iterable, r):
# combinations('ABCD', 2) --> AB AC AD BC BD CD
# combinations(range(4), 3) --> 012 013 023 123
pool = tuple(iterable)
poolsz = len(pool)
if
r > n:
return
indices = list(range(r))
yield
tuple(pool[i]
for
i
in
indices)
while
True
:
# make sure that we're not doing the base case (e.g. ABCD of Comb('ABCD', 4))
for
i
in
reversed(range(r)):
if
indices[i] != i + poolsz - r:
break
else
:
return
indices[i] += 1
for
j
in
range(i+1, r):
indices[j] = indices[j-1] + 1
yield
tuple(pool[i]
for
i
in
indices)


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