Simple examples: Difference between revisions
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Miraheze>Adám Brudzewsky |
Miraheze>Marshall No edit summary |
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=== Indices of multiple elements === | === Indices of multiple elements === | ||
<code class="apl">∊</code> gives us a mask for elements (characters) in the left argument that are members of the right argument: | <code class="apl">∊</code> gives us a mask for elements (characters) in the left argument that are members of the right argument: | ||
< | <source lang=apl> | ||
'mississippi'∊'sp' | 'mississippi'∊'sp' | ||
0 0 1 1 0 1 1 0 1 1 0 | 0 0 1 1 0 1 1 0 1 1 0 | ||
</ | </source> | ||
<code class="apl">⍸</code> gives us the indices where true (1): | <code class="apl">⍸</code> gives us the indices where true (1): | ||
< | <source lang=apl> | ||
⍸'mississippi'∊'sp' | ⍸'mississippi'∊'sp' | ||
3 4 6 7 9 10 | 3 4 6 7 9 10 | ||
</ | </source> | ||
We can combine this into an anonymous infix (dyadic) function: | We can combine this into an anonymous infix (dyadic) function: | ||
< | <source lang=apl> | ||
'mississippi' (⍸∊) 'sp' | 'mississippi' (⍸∊) 'sp' | ||
3 4 6 7 9 10 | 3 4 6 7 9 10 | ||
</ | </source> | ||
{{Works in|[[Dyalog APL]], [[NARS2000]], [[dzaima/APL]]}} | {{Works in|[[Dyalog APL]], [[NARS2000]], [[dzaima/APL]]}} | ||
=== Parenthesis nesting level === | === Parenthesis nesting level === | ||
First we compare all characters to the opening and closing characters; | First we compare all characters to the opening and closing characters; | ||
< | <source lang=apl> | ||
'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | '()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | ||
0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 | 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 | ||
0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 | 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 | ||
</ | </source> | ||
An opening increases the current level, while a closing decreases, so we convert this to ''changes'' (or ''deltas'') by subtracting the bottom row from the top row: | An opening increases the current level, while a closing decreases, so we convert this to ''changes'' (or ''deltas'') by subtracting the bottom row from the top row: | ||
< | <source lang=apl> | ||
-⌿'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | -⌿'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | ||
0 0 0 0 1 0 0 0 0 0 0 1 0 ¯1 0 0 0 0 0 1 0 0 0 0 0 0 1 0 ¯1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 ¯1 ¯1 ¯1 | 0 0 0 0 1 0 0 0 0 0 0 1 0 ¯1 0 0 0 0 0 1 0 0 0 0 0 0 1 0 ¯1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 ¯1 ¯1 ¯1 | ||
</ | </source> | ||
The running sum is what we're looking for: | The running sum is what we're looking for: | ||
< | <source lang=apl> | ||
+\-⌿'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | +\-⌿'()'∘.='plus(square(a),plus(square(b),times(2,plus(a,b)))' | ||
0 0 0 0 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 2 2 2 2 2 2 2 3 3 3 3 3 3 3 4 4 4 4 3 2 1 | 0 0 0 0 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 2 2 2 2 2 2 2 3 3 3 3 3 3 3 4 4 4 4 3 2 1 | ||
</ | </source> | ||
{{Works in|all APLs}} | {{Works in|all APLs}} | ||
{{APL programming language}} | {{APL programming language}} |