Re: Index-of function with structured left-argument

[Dr . Jürgen Sauermann]

Hi again, just saw that this is documented in "info apl" section "3.17.2 Generalized dyadic ⍳". Apparently your ⎕IO is 0 which makes it a bit mysterious. Otherwise:       A←2 2 ⍴ 104 105 106 107       B←3 4 ⍴ 100+⍳100       A 104 105 106 107       B 101 102 103 104 105 106 107 108 109 110 111 112       4 ⎕CR A⍳B ┏→━━━━━━━━━━━━━━━━━━━━━━┓ ↓┏⊖┓   ┏⊖┓   ┏⊖┓   ┏→━━┓┃ ┃┃0┃   ┃0┃   ┃0┃   ┃1 1┃┃ ┃┗━┛   ┗━┛   ┗━┛   ┗━━━┛┃ ┃┏→━━┓ ┏→━━┓ ┏→━━┓ ┏⊖┓  ┃ ┃┃1 2┃ ┃2 1┃ ┃2 2┃ ┃0┃  ┃ ┃┗━━━┛ ┗━━━┛ ┗━━━┛ ┗━┛  ┃ ┃┏⊖┓   ┏⊖┓   ┏⊖┓   ┏⊖┓  ┃ ┃┃0┃   ┃0┃   ┃0┃   ┃0┃  ┃ ┃┗━┛   ┗━┛   ┗━┛   ┗━┛  ┃ ┗∊━━━━━━━━━━━━━━━━━━━━━━┛ Then: - the result has the same shape as A since every element of A is being searched in (the ravel of) B. - The first three and the last five result elements are ⍬ because the A items  101 102 103 (first three) and 108 109 110 111 112 (the last five) were not found in B. Items not found get an index of ⍬ while found ones get the index of B where they (first) occurred in B. Just like in the vector case. The only difference is ⍬ instead of ⎕IO+⍴B for elements not in B. I simply considewred that to be more consistent (and far easier to check) then other alternatives like ⎕IO+⍴B or ⎕IO+⍴,B or ⎕IO+↑⍴B). Best Regards, Jürgen On 4/14/20 11:39 AM, Dr. Jürgen Sauermann wrote: Hi Elias, my best guess is that this is a missing RANK ERROR somewhere. I will look into it. Best Regards, Jürgen On 4/14/20 10:15 AM, Elias Mårtenson wrote: The ISO spec doesn't address what the index-of function should do when the left argument is not a scalar or a one-dimensional array. GNU APL extends this, but I don't really understand in what way. How am I to interpret the output from this?       (2 2 ⍴ 104 105 106 107) ⍳ (3 4 ⍴ 100+⍳100) ┏→━━━━━━━━━━━━━━━━━━━━━━┓ ↓┏⊖┓   ┏⊖┓   ┏⊖┓   ┏⊖┓  ┃ ┃┃0┃   ┃0┃   ┃0┃   ┃0┃  ┃ ┃┗━┛   ┗━┛   ┗━┛   ┗━┛  ┃ ┃┏→━━┓ ┏→━━┓ ┏→━━┓ ┏→━━┓┃ ┃┃0 0┃ ┃0 1┃ ┃1 0┃ ┃1 1┃┃ ┃┗━━━┛ ┗━━━┛ ┗━━━┛ ┗━━━┛┃ ┃┏⊖┓   ┏⊖┓   ┏⊖┓   ┏⊖┓  ┃ ┃┃0┃   ┃0┃   ┃0┃   ┃0┃  ┃ ┃┗━┛   ┗━┛   ┗━┛   ┗━┛  ┃ ┗∊━━━━━━━━━━━━━━━━━━━━━━┛ Regards, Elias