Spiral matrix: Difference between revisions
Add Factor example
No edit summary |
(Add Factor example) |
||
Line 1,441:
{12,11,10,9,8}
}
=={{header|Factor}}==
This is an implementation of Joey Tuttle's method for computing a spiral directly as a list and then reshaping it into a matrix, as described in the [http://rosettacode.org/wiki/Spiral_matrix#J J entry]. To summarize, we construct a list with <code>n*n</code> elements by following some simple rules, then take its cumulative sum, and finally its inverse permutation (or rank in J parlance). This gives us a list which can be reshaped to the final matrix.
<lang factor>USING: arrays grouping io kernel math math.combinatorics
math.ranges math.statistics prettyprint sequences
sequences.repeating ;
IN: rosetta-code.spiral-matrix
: counts ( n -- seq )
[1,b] reverse 2 repeat rest ;
: vals ( n -- seq )
[ 1 swap 2dup [ neg ] bi@ 4array ] [ 2 * 1 - cycle ] bi ;
: evJKT2 ( n -- seq )
[ counts ] [ vals ] bi [ <array> ] 2map concat ;
: spiral ( n -- matrix )
[ evJKT2 cum-sum inverse-permutation ] [ group ] bi ;
: spiral-demo ( -- )
5 9 [ spiral simple-table. nl ] bi@ ;
MAIN: spiral-demo</lang>
{{out}}
<pre>
0 1 2 3 4
15 16 17 18 5
14 23 24 19 6
13 22 21 20 7
12 11 10 9 8
0 1 2 3 4 5 6 7 8
31 32 33 34 35 36 37 38 9
30 55 56 57 58 59 60 39 10
29 54 71 72 73 74 61 40 11
28 53 70 79 80 75 62 41 12
27 52 69 78 77 76 63 42 13
26 51 68 67 66 65 64 43 14
25 50 49 48 47 46 45 44 15
24 23 22 21 20 19 18 17 16
</pre>
=={{header|Fortran}}==
| |||