How to use Apply and Map properly in this situation?

Question

So this does what I want:

#1 <> #2 &["♠", "A"]

♠A

The output is fine. How do I quickly apply this to the list

{{"♠", "A"}, {"♢", "A"}, {"♣", "A"}, {"♡", "A"}}

So that I can combined all of the suits with the Aces? I have tried a mixture of "/", "@" and "/@". None of these worked.

Answer 1

You want to Apply your function at level 1 in the list :

#1 <> #2 & @@@ {{"♠", "A"}, {"♢", "A"}, {"♣", "A"}, {"♡", "A"}}

{"♠A", "♢A", "♣A", "♡A"}

As mentioned at the very top of the docs for Apply, f @@@ expr is is syntactic sugar for Apply[ f, expr, {1} ], and has the same effect as Apply[ f, # ]& /@ expr.

---

Note that #1 <> #2 & parses as StringJoin[#1,#2]&, for which you might as well just use StringJoin :

StringJoin @@@ {{"♠", "A"}, {"♢", "A"}, {"♣", "A"}, {"♡", "A"}}

{"♠A", "♢A", "♣A", "♡A"}