Discussion of the 10th study group can go here. Overview
[ <<< session 9 | session 11 >>>]
This is a wiki post - feel free to edit to add links from the lesson or other useful info.
Jeremy, In the Dyalog editor, once inputted a quad, there is a drop-down menu for pre-defined arrays. Those arrays are mutable. Check out Namespace.
Here are some examples:
I had a personal issue come up which is why I missed this session.
It appears that it is related to the “Migration Level” .
⎕ML determines the degree of migration of the Dyalog APL language towards IBM’s APL2. Setting this variable to other than its default value of 1 changes the interpretation of certain symbols and language constructs. ⎕ML has Namespace scope.
It is a bit more involved than that. You may want to have a look at APL Wiki’s article on quad names.
Thanks for the link. Since Dyalog does not support ⎕a, how can we evaluate lower cases?
Does APL have something like islower(), isupper() or isinstance() in Python?
Monadic ⎕C is casefold
Dyadic ⎕C is casemap; 1 ⎕C text for uppercase and ¯1 ⎕C text for lowercase.
You can then construct islower←{⍵≡¯1 ⎕C ⍵} and isupper←{⍵≡1 ⎕C ⍵}
The closest parallel to Python’s isinstance() would be something like istype←{⍵∊⍨⎕DR ⍺} where the left argument is the data and the right argument a data representation code, e.g. 11 for Boolean, 80 for 1-byte character, 163 for 2-byte integer, 326 for pointer-array, 645 for binary float, etc. See ⎕DR documentation for details.
Here are my solutions to the Dyalog 2022 phase 1 competition problem that was discussed in the class.
The first one builds on Jeremy’s solution and solves the ordering issue by supplying the desired order (ACGT) as a prefix and then subtract 1 from the tallies to account for the added prefix. This works because the keys in the ⌸ operator result are always sorted based on what the operators sees on the RHS first.
Solution 1:
{¯1+{≢⍵}⌸'ACGT',⍵}
Solution 2
{(+/=)⍨ ∘ ⍵ ¨ 'ACGT'}
