How to split a number into its digits in APL

Question

In APL, how can I split an integer or number into a vector containing its digits? What is the most concise (shortest) way of doing this?

Answer 1

You can use the inverse of Decode with base 10:

10⊥⍣¯1⊢

since Decode would take in as many digits as needed and decode them, its inverse would take a number and encode it to as many digits as needed,

or, with ⎕IO←0, you can try to find the indexes of the formatted number inside the digits vector:

⎕D⍳⍕

Demo for both solutions.

This is better than the uglier use of Encode with custom length derived by shaping an array of 10 to the length of the log₁₀ of the input:

{⍵⊤⍨10⍴⍨⌈10⍟1+⍵}

Answer 2

I did this in APL2 by first applying FORMAT and then EXECUTE EACH (though it might be limited to positive integers) :

⍎¨⍕

Try it online!