Distribute a nested list

Question

I would need a function that distributes a nested list in a specified position.
A sample of this function could be:
try={{1,{a,b,c},2},3,4,{5,6}}
DistributeNested[try,{1,2}]

which output would be
{{{1,a,2},3,4,{5,6}},{{1,b,2},3,4,{5,6}},{{1,c,2},3,4,{5,6}}}

How can I realise such a function?

kglr · Accepted Answer

Thread[MapAt[Thread, try, {1}], List, 1]

{{{1, a, 2}, 3, 4, {5, 6}}, 
 {{1, b, 2}, 3, 4, {5, 6}}, 
 {{1, c, 2}, 3, 4, {5, 6}}}

Update: Using the second and third arguments of Thread you can specify the heads and positions of arguments to thread over:
try2 = {{1, {a, b, c}, {e, f, g}}, 3, 4, {5, 6}};

Thread[MapAt[Thread, try2, {1}], List, 1]

{{{1, a, e}, 3, 4, {5, 6}}, 
 {{1, b, f}, 3, 4, {5, 6}}, 
 {{1, c, g}, 3, 4, {5, 6}}}

Thread[MapAt[Thread[#, List, {2}] &, try2, {1}], List, 1]

{{{1, a, {e, f, g}}, 3, 4, {5, 6}},
 {{1, b, {e, f, g}}, 3, 4, {5, 6}},
 {{1, c, {e, f, g}}, 3, 4, {5, 6}}}

Thread[MapAt[Thread[#, List, {3}] &, try2, {1}], List, 1]

{{{1, {a, b, c}, e}, 3, 4, {5, 6}},
 {{1, {a, b, c}, f}, 3, 4, {5, 6}},
 {{1, {a, b, c}, g}, 3, 4, {5, 6}}}

try3 = {{1, foo[a, b, c], bar[e, f, g]}, 3, 4, {5, 6}} ;

Thread[MapAt[Thread[#, foo] &, try3, {1}], List, 1]

{foo[{1, a, bar[e, f, g]},
     {1, b, bar[e, f, g]},
     {1, c, bar[e, f, g]}], 3, 4, {5, 6}}

Thread[MapAt[Thread[#, bar] &, try3, {1}], List, 1]

{bar[{1, foo[a, b, c], e},
     {1, foo[a, b, c], f},
     {1, foo[a, b, c], g}], 3, 4, {5, 6}}

Thread[MapAt[Thread[#, foo] &, try3, {1}], foo, 1]

foo[{{1, a, bar[e, f, g]}, 3, 4, {5, 6}}, 
    {{1, b, bar[e, f, g]}, 3, 4, {5, 6}}, 
    {{1, c, bar[e, f, g]}, 3, 4, {5, 6}}]

Distribute a nested list

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