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Frame agreement: Difference between revisions
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(Reorganize page to cover general frame conformance; add model for prefix agreement.) |
m (→Model) |
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x←⍳2 | x←⍳2 | ||
y←2 3 2⍴⍳12 | y←2 3 2⍴⍳12 | ||
x{⍺⍵}⍤99 2⊢y | x{⍺⍵}⍤99 2⊢y ⍝ 1-to-n pairing; ⍤99 corresponds to empty frame | ||
┌───┬─────┐ | ┌───┬─────┐ | ||
│1 2│1 2 │ | │1 2│1 2 │ | ||
| Line 17: | Line 17: | ||
│ │11 12│ | │ │11 12│ | ||
└───┴─────┘ | └───┴─────┘ | ||
x{⍺⍵}⍤0 2⊢y | x{⍺⍵}⍤0 2⊢y ⍝ 1-to-1 pairing; frames match; (,2) ≡ (,2) | ||
┌─┬─────┐ | ┌─┬─────┐ | ||
│1│1 2 │ | │1│1 2 │ | ||
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=== Model === | === Model === | ||
In dialects that do not feature frame prefix agreement, it can nevertheless be utilised by the introduction of an explicit operator: | In dialects that do not feature frame prefix agreement, it can nevertheless be utilised by the introduction of an explicit operator: | ||
<syntaxhighlight lang=apl> | <syntaxhighlight lang=apl> | ||
_FA_←{ | _FA_←{ | ||
assert←{0≡⍵:' | assert←{0≡⍵:'error: no common frame prefix' ⎕SIGNAL 4 ⋄ ⍵} | ||
r←1↓⌽3⍴⌽⍵⍵ ⋄ ar←≢¨p←⍴¨⍺⍵ ⍝ dyadic ranks, array ranks, shapes | |||
c←r{⍺>0:⍺⌊⍵ ⋄ 0⌈⍺+⍵}¨ar ⍝ cell ranks | |||
fl fr←(-c)↓¨p ⍝ left and right frames | |||
k←{⍬≡⍵:99 ⋄ -≢⍵} | s←fl{⍺<⍥≢⍵:⍺ ⋄ ⍵}fr ⍝ shorter frame | ||
assert ⍺∧⍥( | k←{⍬≡⍵:99 ⋄ -≢⍵}s ⍝ relative rank | ||
⍺ | assert ⍺∧⍥(s≡(≢s)↑⍴)⍵: ⍝ do frames agree? | ||
⍺ ⍺⍺⍤c⍤k⊢⍵ | |||
} | } | ||
x+_FA_ 0 1⊢y | x+_FA_ 0 1⊢y | ||
| Line 148: | Line 148: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
{{Works in|[[Dyalog APL]]}} | {{Works in|[[Dyalog APL]]}} | ||
[[Category:Leading axis theory]][[Category:Function characteristics]][[Category:Conformability]]{{APL features}} | [[Category:Leading axis theory]][[Category:Function characteristics]][[Category:Conformability]]{{APL features}} | ||