There are some other questions on this topic but I could not get an answer from reading them. What I want to do is use Apply
on some of the arguments of a function, h
, and then Map
on another argument. Here is what I attempted:
Map[Apply[{h[#, ##]} &, {a, b}] &, {1, 2}]
(* ===>{{h[a, a, b]}, {h[a, a, b]}} *)
The elements I want to Map
over never get used. But this is not what I want. I want just
{h[1,a,b],h[2,a,b]}
I could use Table instead of Map but it's slow (slower than just using Apply
twice) and I was hoping Map
would be faster.
I understand that Apply
is using both #
and ##
but I'm not sure what syntax is correct to force the first Slot
to be used by Map
instead of Apply
.
EDIT: This is more like what I actually want to do:
Map[Apply[{h1[#, ##],h2[#, ##]} &, {RandomReal[], RandomReal[]}] &, {1, 2}]
So I want output as
{{h1[1, a1,b1], h2[1, a1,b1]},{h1[2, a2,b2], h2[2, a2,b2]}}
where I a
's and b
's are the random numbers. So to get this, I think the order of Apply
and Map
is important.
Answer
One option is to separate the slots by using an explicit Function
for the second argument
Map[Function[arg, Apply[{h[arg, ##]} &, {a, b}]], {1, 2}]
Regarding your updated question. The approach is the same
Map[Function[arg, Apply[{h1[arg, ##], h2[arg, ##]} &,
{RandomReal[], RandomReal[]}]], {1, 2}]
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