Time for an 2014 update…

Task/Filter/Deja-Vu/filter-1.djv

@@ -0,0 +1,11 @@
+filter pred lst:
+	]
+	for value in copy lst:
+		if pred @value:
+			@value
+	[
+
+even x:
+	= 0 % x 2
+
+!. filter @even [ 0 1 2 3 4 5 6 7 8 9 ]

Task/Filter/Deja-Vu/filter-2.djv

@@ -0,0 +1,16 @@
+local :lst [ 0 1 2 3 4 5 6 7 8 9 ]
+
+filter-destructively pred lst:
+	local :tmp []
+	while lst:
+		pop-from lst
+		if pred dup:
+			push-to tmp
+		else:
+			drop
+	while tmp:
+		push-to lst pop-from tmp
+
+filter-destructively @even lst
+
+!. lst

Task/Filter/NetRexx/filter.netrexx

@@ -0,0 +1,63 @@
+/* NetRexx */
+options replace format comments java crossref symbols nobinary
+numeric digits 5000
+
+-- =============================================================================
+class RFilter public
+  properties indirect
+    filter = RFilter.ArrayFilter
+  -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  method main(args = String[]) public static
+    arg = Rexx(args)
+    RFilter().runSample(arg)
+    return
+  -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  method runSample(arg) public
+    sd1 = Rexx[]
+    sd2 = Rexx[]
+
+    say 'Test data:'
+    sd1 = makeSampleData(100)
+    display(sd1)
+    setFilter(RFilter.EvenNumberOnlyArrayFilter())
+    say
+    say 'Option 1 (copy to a new array):'
+    sd2 = getFilter().filter(sd1)
+    display(sd2)
+    say
+    say 'Option 2 (replace the original array):'
+    sd1 = getFilter().filter(sd1)
+    display(sd1)
+    return
+  -- ---------------------------------------------------------------------------
+  method display(sd = Rexx[]) public static
+    say '-'.copies(80)
+    loop i_ = 0 to sd.length - 1
+      say sd[i_] '\-'
+      end i_
+    say
+    return
+  -- ---------------------------------------------------------------------------
+  method makeSampleData(size) public static returns Rexx[]
+    sd = Rexx[size]
+    loop e_ = 0 to size - 1
+      sd[e_] = (e_ + 1 - size / 2) / 2
+      end e_
+    return sd
+
+-- =============================================================================
+class RFilter.ArrayFilter abstract
+  -- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
+  method filter(array = Rexx[]) public abstract returns Rexx[]
+-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
+class RFilter.EvenNumberOnlyArrayFilter extends RFilter.ArrayFilter
+  -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  method filter(array = Rexx[]) public returns Rexx[]
+    clist = ArrayList(Arrays.asList(array))
+    li = clist.listIterator()
+    loop while li.hasNext()
+      e_ = Rexx li.next
+      if \e_.datatype('w'), e_ // 2 \= 0 then li.remove()
+      end
+    ry = Rexx[] clist.toArray(Rexx[clist.size()])
+    return ry

Task/Filter/PL-I/filter.pli

@@ -0,0 +1,28 @@
+(subscriptrange):
+filter_values: procedure options (main); /* 15 November 2013 */
+   declare a(20) fixed, b(*) fixed controlled;
+   declare (i, j, n) fixed binary;
+
+   a = random()*99999; /* fill the array with random elements from 0-99998 */
+   put list ('Unfiltered values:');
+   put skip edit (a) (f(6));
+   /* Loop to count the number of elements that will be filtered */
+   n = 0;
+   do i = 1 to hbound(a);
+      n = n + filter(a(i));
+   end;
+   allocate b(n);
+   j = 0;
+   do i = 1 to hbound(a);
+      if filter(a(i)) then do; j = j + 1; b(j) = a(i); end;
+   end;
+   put skip list ('Filtered values:');
+   put skip edit (b) (f(6));
+
+filter: procedure (value) returns (bit(1));
+   declare value fixed;
+
+   return (iand(abs(value), 1) = 0);
+end filter;
+
+end filter_values;

Task/Filter/REXX/filter-1.rexx

@@ -0,0 +1,20 @@
+/*REXX program selects all even numbers from an array  ──►  a new array.*/
+parse arg N seed .                     /*get optional parameters from CL*/
+if N=='' | N==','          then N=50   /*Not specified? Then use default*/
+if seed\=='' & seed\==','  then call random ,,seed  /*for repeatability.*/
+old.=                                  /*the OLD array, all null so far.*/
+new.=                                  /*the NEW array, all null so far.*/
+               do i=1  for N           /*gen  N  random numbers ──►  OLD*/
+               old.i=random(1,99999)   /*randum number  1  ──►  99999   */
+               end   /*i*/
+#=0                                    /*numb. of elements in NEW so far*/
+      do j=1  for N                    /*process the OLD array elements.*/
+      if old.j//2 \== 0  then iterate  /*if element isn't even, skip it.*/
+      #=#+1                            /*bump the number of NEW elements*/
+      new.#=old.j                      /*assign it to the NEW array.    */
+      end   /*j*/
+
+            do k=1  for #              /*display all the NEW  numbers.  */
+            say  right('new.'k, 20)  "="  right(new.k,9)   /*show a line*/
+            end   /*k*/
+                                       /*stick a fork in it, we're done.*/

Task/Filter/REXX/filter-2.rexx

@@ -0,0 +1 @@
+      if old.j//2 \== 0  then iterate

Task/Filter/REXX/filter-3.rexx

@@ -0,0 +1 @@
+      if old.j//2        then iterate

Task/Filter/REXX/filter-4.rexx

@@ -0,0 +1,18 @@
+/*REXX pgm find all even numbers from an array,  marks a control array. */
+arse arg N seed .                     /*get optional parameters from CL*/
+f N=='' | N==','          then N=50   /*Not specified? Then use default*/
+f seed\=='' & seed\==','  then call random ,,seed  /*for repeatability.*/
+
+              do i=1  for N           /*gen  N  random numbers ──►  OLD*/
+              @.i=random(1,99999)     /*randum number  1  ──►  99999   */
+              end   /*i*/
+.=0                                   /*numb. of elements in NEW so far*/
+     do j=1  for N                    /*process the OLD array elements.*/
+     if @.j//2 \==0  then !.j=1       /*mark  !  array that it's ¬even.*/
+     end   /*j*/
+
+           do k=1  for N              /*display all the @ even numbers.*/
+           if !.k  then iterate       /*if it's marked ¬even,  skip it.*/
+           say  right('array.'k, 20)  "="  right(@.k,9)   /*show a line*/
+           end   /*k*/
+                                      /*stick a fork in it, we're done.*/

Task/Filter/REXX/filter-5.rexx

@@ -0,0 +1,18 @@
+/*REXX pgm find all even numbers from an array,  marks ¬ even numbers.  */
+parse arg N seed .                     /*get optional parameters from CL*/
+if N=='' | N==','          then N=50   /*Not specified? Then use default*/
+if seed\=='' & seed\==','  then call random ,,seed  /*for repeatability.*/
+
+               do i=1  for N           /*gen  N  random numbers ──►  OLD*/
+               @.i=random(1,99999)     /*randum number  1  ──►  99999   */
+               end   /*i*/
+
+      do j=1  for N                    /*process the OLD array elements.*/
+      if @.j//2 \==0  then @.j=        /*mark  @  array that it's ¬even.*/
+      end   /*j*/
+
+            do k=1  for N              /*display all the @ even numbers.*/
+            if @.k==''  then iterate   /*if it's marked ¬even,  skip it.*/
+            say  right('array.'k, 20)  "="  right(@.k,9)   /*show a line*/
+            end   /*k*/
+                                       /*stick a fork in it, we're done.*/

Task/Filter/REXX/filter.rexx

@@ -1,26 +0,0 @@
-/*REXX program selects all even numbers from an array  ──► a new array. */
-numeric digits 210000                  /*handle past  1m  for Fibonacci.*/
-old.=                                  /*the OLD array, all null so far.*/
-new.=                                  /*the NEW array, all null so far.*/
-  do j=-40 to 40;  old.j=fib(j);  end  /*put 81 Fibonacci numbs ==> OLD */
-news=0                                 /*numb. of elements in NEW so far*/
-
-/*══════════════════════════════════════════════════════════════════════*/
-      do k=-40  while old.k\==''       /*process the OLD array elements.*/
-      if old.k//2 \== 0 then iterate   /*if element isn't even, skip it.*/
-      news=news+1                      /*bump the number of NEW elements*/
-      new.news=old.k                   /*assign it to the NEW array.    */
-      end
-/*══════════════════════════════════════════════════════════════════════*/
-
-      do j=1  for news                 /*display all the NEW  numbers.  */
-      say 'new.'j "=" new.j
-      end
-exit                                   /*stick a fork in it, we're done.*/
-/*─────────────────────────────────────FIB subroutine (non-recursive)───*/
-fib: procedure; parse arg n; na=abs(n); if na<2 then return na /*special*/
-a=0;  b=1
-                do j=2 to na; s=a+b; a=b; b=s; end
-
-if n>0 | na//2==1  then return  s      /*if positive or odd negative... */
-                   else return -s      /*return a negative Fib number.  */

Task/Filter/UNIX-Shell/filter-1.sh

@@ -3,6 +3,3 @@ unset e[@]
 for ((i=0;i<${#a[@]};i++)); do
   [ $((a[$i]%2)) -eq 0 ] && e[$i]="${a[$i]}"
 done
-
-echo "${a[@]}"
-echo "${e[@]}"

Task/Filter/UNIX-Shell/filter-2.sh

@@ -0,0 +1,2 @@
+a=(1 2 3 4 5)
+read -a e -d\n < <(printf '%s\n' "${a[@]}" | grep '[02468]$')

Task/Filter/UNIX-Shell/filter-3.sh

@@ -0,0 +1,2 @@
+echo "${a[@]}"
+echo "${e[@]}"