Returns an association mapping each letter to its number of occurrences.
LetterCounts["string"]
LetterCounts["string", n]
LetterCounts["string", n, {"c1", "c2", …}]
LetterCounts[{"string1", "string2", …}, …]
LetterCounts["banana"]
→ <|a -> 3, n -> 2, b -> 1|>LetterCounts["ab12cd34ab12", 2]
→ <|ab -> 2, cd -> 1|>LetterCounts[{"hello", "world", "!"}]
→ {<|l -> 2, o -> 1, e -> 1, h -> 1|>, <|d -> 1, l -> 1, r -> 1, o -> 1, w -> 1|>, <||>}LetterCounts["abcde", 0]
→
LetterCounts::arg2: Positive integer expected in position 2.
LetterCounts[abcde, 0]