Langton's ant: Difference between revisions
Content added Content deleted
(added GFA Basic example) |
m (→{{header|REXX}}: changed/added comments and whitespace, changed indentations.) |
||
| Line 4,649: | Line 4,649: | ||
This REXX program automatically justifies (or ''crops'') the '''left''', '''right''', '''top''' and '''bottom''' of the ant's walk field on the screen. |
This REXX program automatically justifies (or ''crops'') the '''left''', '''right''', '''top''' and '''bottom''' of the ant's walk field on the screen. |
||
<br>Or in other words, this REXX program only shows the pertinent part of the ant's walk-field. |
<br>Or in other words, this REXX program only shows the pertinent part of the ant's walk-field. |
||
<lang rexx>/*REXX program implements Langton's ant walk and displays the ant's path*/ |
<lang rexx>/*REXX program implements Langton's ant walk and displays the ant's path (finite field).*/ |
||
parse arg dir char . /* |
parse arg dir char . /*obtain optional arguments from the CL*/ |
||
if char=='' then char='#' |
if char=='' | char=="," then char='#' /*binary colors: 0≡white, 1≡black. */ |
||
@.=0 /*define stem array |
@.=0 /*define stem array, default: all white*/ |
||
Lb=1 ; Rb=100 /* left |
Lb=1 ; Rb=100 /*the left boundary, right boundary*/ |
||
Bb=1 ; Tb=100 /*bottom " top " */ |
Bb=1 ; Tb=100 /*the bottom " top " */ |
||
x=(Rb-Lb)%2 ; y=(Tb-Bb)%2 /*approximate center |
x=(Rb-Lb)%2 ; y=(Tb-Bb)%2 /*approximate center where walk starts.*/ |
||
| ⚫ | |||
if dir=='' |
if dir=='' then dir=random(1, 4) /*ant is facing a random direction, */ |
||
| ⚫ | |||
/* [↓] ant walks hither and thither. */ |
|||
/*───────────────────────────────────────────ant walks hither & thither.*/ |
|||
do steps=1 until x<Lb | x>Rb | y<Bb | y>Tb /*walk until out─of─bounds*/ |
do steps=1 until x<Lb | x>Rb | y<Bb | y>Tb /*walk until the ant is out─of─bounds.*/ |
||
black=@.x.y; @.x.y= \ @.x.y /*ant's cell color code |
black=@.x.y; @.x.y= \ @.x.y /*invert (flip) ant's cell color code.*/ |
||
if black then dir=dir-1 /*if cell was black, turn left.*/ |
if black then dir=dir-1 /*if cell color was black, turn left.*/ |
||
else dir=dir+1 /* " " " white, turn right.*/ |
else dir=dir+1 /* " " " " white, turn right.*/ |
||
dir=$.dir /*possibly adjust for under/over.*/ |
dir=$.dir /*possibly adjust for under/over. */ |
||
select /*ant walks direction it's facing*/ |
select /*ant walks the direction it's facing. */ |
||
when dir==1 then y= y + 1 /*walking north? Then go |
when dir==1 then y= y + 1 /*is ant walking north? Then go up. */ |
||
when dir==2 then x= x + 1 /* " east? " " |
when dir==2 then x= x + 1 /* " " " east? " " right.*/ |
||
when dir==3 then y= y - 1 /* " south? " " |
when dir==3 then y= y - 1 /* " " " south? " " down. */ |
||
when dir==4 then x= x - 1 /* " west? " " |
when dir==4 then x= x - 1 /* " " " west? " " left. */ |
||
end /*select*/ |
end /*select*/ |
||
end /*steps*/ |
end /*steps*/ /* [↑] the ant is finished walking. */ |
||
/*───────────────────────────────────────────the ant is finished walking*/ |
|||
say center(" Langton's ant walked" steps 'steps. ', 79, "─"); say |
say center(" Langton's ant walked " steps ' steps. ', 79, "─"); say |
||
/* [↓] show Langton's ant's trail*/ |
/* [↓] show Langton's ant's trail. */ |
||
do minx =Lb to Rb /*find leftmost non─blank column.*/ |
do minx =Lb to Rb /*find the leftmost non─blank column. */ |
||
do y=Bb to Tb /*search row by row for the |
do y=Bb to Tb /*search row by row for the minimum. */ |
||
if @.minx.y then leave minx /*found one, now quit searching. |
if @.minx.y then leave minx /*found one, now we can quit searching.*/ |
||
end /*y*/ |
end /*y*/ |
||
end /*minx*/ /*above code crops left of array.*/ |
end /*minx*/ /* [↑] above code crops left of array.*/ |
||
do y=Tb to Bb by -1; _= /*display a |
do y=Tb to Bb by -1; _= /*display a single row of cells. */ |
||
do x=minx to Rb; _=_ || @.x.y /*build a cell row for display. */ |
do x=minx to Rb; _=_ || @.x.y /*build a cell row for the display. */ |
||
end /*x*/ |
end /*x*/ |
||
_=strip(translate(_,char,10), 'T') /*color the cells: black |
_=strip(translate(_,char,10), 'T') /*color the cells: black or white. */ |
||
if _\=='' then say _ /* |
if _\=='' then say _ /*display line (strip trailing blanks).*/ |
||
end /*y*/ /*stick a fork in it, we're done.*/</lang> |
end /*y*/ /*stick a fork in it, we're all done. */</lang> |
||
'''output''' |
'''output''' when using the default inputs: |
||
<br><br>(Shown at <sup>'''3'''</sup>/<sub>'''4'''</sub> size.) |
|||
<br>(Shown at three-quarter size.) |
|||
<pre style="font-size:75%"> |
<pre style="font-size:75%"> |
||
────────────────────── Langton's ant walked 11759 steps. ────────────────────── |
────────────────────── Langton's ant walked 11759 steps. ────────────────────── |
||
## |
## |
||