Strand Assignment: Difference between revisions
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<table border="0" cellpadding="5" cellspacing="0" summary=""> | <table border="0" cellpadding="5" cellspacing="0" summary=""> | ||
<tr> | <tr> | ||
<td>< | <td><apll> (A<sub>1</sub> A<sub>2</sub> ... A<sub>n</sub>)←R</apll></td> | ||
<td></td> | <td></td> | ||
<td></td> | <td></td> | ||
<td>Assigns the successive items of < | <td>Assigns the successive items of <apll>R</apll> to the names. </td> | ||
</tr> | </tr> | ||
</table> | </table> | ||
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</tr> | </tr> | ||
<tr> | <tr> | ||
<td>< | <td><apll>A<sub>1</sub> A<sub>2</sub> ... A<sub>n</sub></apll> are assignable names, <apll>R</apll> is a scalar or vector. | ||
</td> | </td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If < | <td>If <apll>1<⍴⍴R</apll>, signal a <apll>RANK ERROR</apll>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If < | <td>If <apll>R</apll> is a scalar or one element vector, its item is assigned to each name, as in <apll>A<sub>i</sub>←⊃⍬⍴R</apll>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Otherwise, assume there are < | <td>Otherwise, assume there are <apll>n</apll> names in the list:</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>If < | <td>If <apll>n≠⍴R</apll>, signal a <apll>LENGTH ERROR</apll>.</td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
<td>Otherwise, each successive item of < | <td>Otherwise, each successive item of <apll>R</apll> is assigned to each successive name, as in <apll>A<sub>i</sub>←i⊃R</apll>.</td> | ||
</tr> | </tr> | ||
</table> | </table> | ||
<br /> | <br /> | ||
<br /> | <br /> | ||
For example, < | For example, <apll>(A B C)←⊂⍳3</apll> is shorthand for <apll>A←B←C←⍳3</apll>. In contrast, <apll>(A B C)←⍳3</apll> is shorthand for <apll>A←1 ⋄ B←2 ⋄ C←3</apll>. | ||
Note that < | Note that <apll>(A B)←B A</apll> is a simple and efficient way to swap the values of the two names. | ||
Revision as of 22:31, 9 April 2008
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| A1 A2 ... An are assignable names, R is a scalar or vector. | ||||
| If 1<⍴⍴R, signal a RANK ERROR. | ||||
| If R is a scalar or one element vector, its item is assigned to each name, as in Ai←⊃⍬⍴R. | ||||
| Otherwise, assume there are n names in the list: | ||||
| If n≠⍴R, signal a LENGTH ERROR. | ||||
| Otherwise, each successive item of R is assigned to each successive name, as in Ai←i⊃R. |
For example, (A B C)←⊂⍳3 is shorthand for A←B←C←⍳3. In contrast, (A B C)←⍳3 is shorthand for A←1 ⋄ B←2 ⋄ C←3.
Note that (A B)←B A is a simple and efficient way to swap the values of the two names.
