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Task/Visualize-a-tree/0DESCRIPTION

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+A tree structure (i.e. a rooted, connected acyclic graph) is often used in programming.  It's often helpful to visually examine such a structure.  There are many ways to represent trees to a reader, such as indented text (à la unix <code>tree</code> command), nested HTML tables, hierarchical GUI widgets, 2D or 3D images, etc.
+
+'''Task''': Write a program to produce a visual representation of some tree.  The content of the tree doesn't matter, nor does the output format, the only requirement being that the output is human friendly. Make do with the vague term "friendly" the best you can.

Task/Visualize-a-tree/BBC-BASIC/visualize-a-tree.bbc

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+      INSTALL @lib$+"WINLIB5"
+      ON ERROR SYS "MessageBox", @hwnd%, REPORT$, 0, 0 : QUIT
+
+      REM!WC Windows constants:
+      TVI_SORT = -65533
+      TVIF_TEXT = 1
+      TVM_INSERTITEM = 4352
+      TVS_HASBUTTONS = 1
+      TVS_HASLINES = 2
+      TVS_LINESATROOT = 4
+
+      REM. TV_INSERTSTRUCT
+      DIM tvi{hParent%,       \
+      \       hInsertAfter%,  \
+      \       mask%,          \
+      \       hItem%,         \
+      \       state%,         \
+      \       stateMask%,     \
+      \       pszText%,       \
+      \       cchTextMax%,    \
+      \       iImage%,        \
+      \       iSelectedImage%,\
+      \       cChildren%,     \
+      \       lParam%         \
+      \      }
+
+      SYS "InitCommonControls"
+      hTree% = FN_createwindow("SysTreeView32", "", 0, 0, @vdu.tr%, @vdu.tb%, 0, \
+      \                        TVS_HASLINES OR TVS_HASBUTTONS OR TVS_LINESATROOT, 0)
+      hroot% = FNinsertnode(0, "Root")
+      hchild1% = FNinsertnode(hroot%, "Child 1")
+      hchild2% = FNinsertnode(hroot%, "Child 2")
+      hchild11% = FNinsertnode(hchild1%, "Grandchild 1")
+      hchild12% = FNinsertnode(hchild1%, "Grandchild 2")
+      hchild21% = FNinsertnode(hchild2%, "Grandchild 3")
+      hchild22% = FNinsertnode(hchild2%, "Grandchild 4")
+
+      REPEAT
+        WAIT 1
+      UNTIL FALSE
+      END
+
+      DEF FNinsertnode(hparent%, text$)
+      LOCAL hnode%
+      text$ += CHR$0
+
+      tvi.hParent% = hparent%
+      tvi.hInsertAfter% = TVI_SORT
+      tvi.mask% = TVIF_TEXT
+      tvi.pszText% = !^text$
+
+      SYS "SendMessage", hTree%, TVM_INSERTITEM, 0, tvi{} TO hnode%
+      IF hnode% = 0 ERROR 100, "TVM_INSERTITEM failed"
+      SYS "InvalidateRect", hTree%, 0, 0
+      = hnode%

Task/Visualize-a-tree/C/visualize-a-tree.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct stem_t *stem;
+struct stem_t { const char *str; stem next; };
+
+void tree(int root, stem head)
+{
+	static const char *sdown = "  |", *slast = "  `", *snone = "   ";
+	struct stem_t col = {0, 0}, *tail;
+
+	for (tail = head; tail; tail = tail->next) {
+		printf("%s", tail->str);
+		if (!tail->next) break;
+	}
+
+	printf("--%d\n", root);
+
+	if (root <= 1) return;
+
+	if (tail && tail->str == slast)
+		tail->str = snone;
+
+	if (!tail)	tail = head = &col;
+	else		tail->next = &col;
+
+	while (root) { // make a tree by doing something random
+		int r = 1 + (rand() % root);
+		root -= r;
+		col.str = root ? sdown : slast;
+
+		tree(r, head);
+	}
+
+	tail->next = 0;
+}
+
+int main(int c, char**v)
+{
+	int n;
+	if (c < 2 || (n = atoi(v[1])) < 0) n = 8;
+
+	tree(n, 0);
+	return 0;
+}

Task/Visualize-a-tree/D/visualize-a-tree.d

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+import std.stdio, std.conv, std.algorithm, std.array;
+
+struct BTNode(T) { T value; BTNode* left, right; }
+
+string[] treeIndent(T)(in BTNode!T* t) {
+    if (t is null) return ["-- (null)"];
+    const tr = treeIndent(t.right);
+    return text("--", t.value) ~
+           map!q{"  |" ~ a}(treeIndent(t.left)).array() ~
+           ("  `" ~ tr[0]) ~ map!q{"   " ~ a}(tr[1..$]).array();
+}
+
+void main () {
+    static N(T)(T v, BTNode!T* l=null, BTNode!T* r=null) {
+        return new BTNode!T(v, l, r);
+    }
+
+    const tree = N(1, N(2, N(4, N(7)), N(5)), N(3, N(6, N(8), N(9))));
+    writefln("%-(%s\n%)", tree.treeIndent());
+}

Task/Visualize-a-tree/Go/visualize-a-tree.go

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+package main
+
+import (
+    "encoding/json"
+    "fmt"
+    "log"
+)
+
+type Node struct {
+    Name     string
+    Children []*Node
+}
+
+func main() {
+    tree := &Node{"root", []*Node{
+        &Node{"a", []*Node{
+            &Node{"d", nil},
+            &Node{"e", []*Node{
+                &Node{"f", nil},
+            }}}},
+        &Node{"b", nil},
+        &Node{"c", nil},
+    }}
+    b, err := json.MarshalIndent(tree, "", "   ")
+    if err != nil {
+        log.Fatal(err)
+    }
+    fmt.Println(string(b))
+}

Task/Visualize-a-tree/Haskell/visualize-a-tree.hs

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+data Tree a = Empty | Node { value :: a, left :: Tree a, right :: Tree a }
+	deriving (Show, Eq)
+
+tree = Node 1 (Node 2 (Node 4 (Node 7 Empty Empty) Empty)
+	(Node 5 Empty Empty)) (Node 3 (Node 6 (Node 8 Empty Empty)
+	(Node 9 Empty Empty)) Empty)
+
+treeIndent Empty = ["-- (nil)"]
+treeIndent t = ["--" ++ show (value t)]
+	++ map ("  |"++) ls ++ ("  `" ++ r):map ("   "++) rs
+	where
+	(r:rs) = treeIndent$right t
+	ls     = treeIndent$left t
+
+main = mapM_ putStrLn $ treeIndent tree

Task/Visualize-a-tree/JavaScript/visualize-a-tree.js

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+<!doctype html>
+<html id="doc">
+  <head><meta charset="utf-8"/>
+    <title>Stuff</title>
+    <script type="application/javascript">
+	function gid(id) { return document.getElementById(id); }
+
+	function ce(tag, cls, parent_node) {
+		var e = document.createElement(tag);
+		e.className = cls;
+		if (parent_node) parent_node.appendChild(e);
+		return e;
+	}
+
+	function dom_tree(id) {
+		gid('tree').textContent = "";
+		gid('tree').appendChild(mktree(gid(id), null));
+	}
+
+	function mktree(e, p) {
+		var t = ce("div", "tree", p);
+		var tog = ce("span", "toggle", t);
+		var h = ce("span", "tag", t);
+
+		if (e.tagName === undefined) {
+			h.textContent = "#Text";
+			var txt = e.textContent;
+			if (txt.length > 0 && txt.match(/\S/)) {
+				h = ce("div", "txt", t);
+				h.textContent = txt;
+			}
+			return t;
+		}
+
+		tog.textContent = "−";
+		tog.onclick = function () { clicked(tog); }
+		h.textContent = e.nodeName;
+
+		var l = e.childNodes;
+		for (var i = 0; i != l.length; i++)
+			mktree(l[i], t);
+		return t;
+	}
+
+	function clicked(e) {
+		var is_on = e.textContent == "−";
+		e.textContent = is_on ? "+" : "−";
+		e.parentNode.className = is_on ? "tree-hide" : "tree";
+	}
+    </script>
+    <style>
+      #tree { white-space: pre; font-family: monospace; border: 1px solid }
+      .tree > .tree-hide, .tree > .tree
+		{ margin-left: 2em; border-left: 1px dotted rgba(0,0,0,.2)}
+      .tree-hide > .tree, .tree-hide > .tree-hide { display: none }
+      .tag { color: navy }
+      .tree-hide > .tag { color: maroon }
+      .txt { color: gray; padding: 0 .5em; margin: 0 .5em 0 2em; border: 1px dotted rgba(0,0,0,.1) }
+      .toggle { display: inline-block; width: 2em; text-align: center }
+    </style>
+  </head>
+  <body>
+    <article>
+      <section>
+        <h1>Headline</h1>
+        Blah blah
+      </section>
+      <section>
+        <h1>More headline</h1>
+        <blockquote>Something something</blockquote>
+        <section><h2>Nested section</h2>
+	  Somethin somethin list:
+	  <ul>
+	    <li>Apples</li>
+	    <li>Oranges</li>
+	    <li>Cetera Fruits</li>
+	  </ul>
+	</section>
+      </section>
+    </article>
+    <div id="tree"><a href="javascript:dom_tree('doc')">click me</a></div>
+  </body>
+</html>

Task/Visualize-a-tree/Mathematica/visualize-a-tree-1.math

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+edges = {1 \[DirectedEdge] 2, 1 \[DirectedEdge] 3, 2 \[DirectedEdge] 4, 2 \[DirectedEdge] 5,
+              3 \[DirectedEdge] 6, 4 \[DirectedEdge] 7};
+t = TreeGraph[edges, GraphStyle -> "VintageDiagram"]

Task/Visualize-a-tree/Mathematica/visualize-a-tree-2.math

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+TreeForm[Defer@
+  TreeGraph[{1 \[DirectedEdge] 2, 1 \[DirectedEdge] 3, 2 \[DirectedEdge] 4, 2 \[DirectedEdge] 5,
+   3 \[DirectedEdge] 6,  4 \[DirectedEdge] 7}, VertexLabels -> "Name"]]

Task/Visualize-a-tree/Mathematica/visualize-a-tree-3.math

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+OpenerView[{1, Column@{OpenerView[{2, Column@{OpenerView[{4, 7}, True], 5}}, True],
+     OpenerView[{3,  OpenerView[{TraditionalForm[Cos[x]], Plot[Cos[x], {x, 0, 10}, ImageSize -> 150]},
+     True]}, True]}}, True]

Task/Visualize-a-tree/Maxima/visualize-a-tree.maxima

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+load(graphs)$
+
+g: random_tree(10)$
+
+is_tree(g);
+true
+
+draw_graph(g)$

Task/Visualize-a-tree/Perl-6/visualize-a-tree.pl6

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+sub visualize-tree($tree, &label, &children,
+                   :$indent = '',
+                   :@mid = ('├─', '│ '),
+                   :@end = ('└─', '  '),
+) {
+    sub visit($node, *@pre) {
+        gather {
+            take @pre[0] ~ label($node);
+            my @children := children($node);
+            my $end = @children.end;
+            for @children.kv -> $_, $child {
+                when $end { take visit($child, (@pre[1] X~ @end)) }
+                default   { take visit($child, (@pre[1] X~ @mid)) }
+            }
+        }
+    }
+    visit($tree, $indent xx 2);
+}
+
+# example tree built up of pairs
+my $tree = root=>[a=>[a1=>[a11=>[]]],b=>[b1=>[b11=>[]],b2=>[],b3=>[]]];
+
+.say for visualize-tree($tree, *.key, *.value.list);

Task/Visualize-a-tree/Prolog/visualize-a-tree.pro

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+% direction may be horizontal/vertical/list
+display_tree(Direction) :-
+	sformat(A, 'Display tree ~w', [Direction]),
+	new(D, window(A)),
+	send(D, size, size(350,200)),
+	new(T, tree(text('Root'))),
+	send(T, neighbour_gap, 10),
+	new(S1, node(text('Child1'))),
+	new(S2, node(text('Child2'))),
+	send_list(T, son,[S1,S2]),
+	new(S11, node(text('Grandchild1'))),
+	new(S12, node(text('Grandchild2'))),
+	send_list(S1, son, [S11, S12]),
+	new(S21, node(text('Grandchild3'))),
+	new(S22, node(text('Grandchild4'))),
+	send_list(S2, son, [S21, S22]),
+	send(T, direction, Direction),
+	send(D, display, T),
+	send(D, open).

Task/Visualize-a-tree/Python/visualize-a-tree.py

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+Python 3.2.3 (default, May  3 2012, 15:54:42)
+[GCC 4.6.3] on linux2
+Type "copyright", "credits" or "license()" for more information.
+>>> help('pprint.pprint')
+Help on function pprint in pprint:
+
+pprint.pprint = pprint(object, stream=None, indent=1, width=80, depth=None)
+    Pretty-print a Python object to a stream [default is sys.stdout].
+
+>>> from pprint import pprint
+>>> for tree in [ (1, 2, 3, 4, 5, 6, 7, 8),
+	          (1, (( 2, 3 ), (4, (5, ((6, 7), 8))))),
+	          ((((1, 2), 3), 4), 5, 6, 7, 8) ]:
+	print("\nTree %r can be pprint'd as:" % (tree, ))
+	pprint(tree, indent=1, width=1)
+
+	
+
+Tree (1, 2, 3, 4, 5, 6, 7, 8) can be pprint'd as:
+(1,
+ 2,
+ 3,
+ 4,
+ 5,
+ 6,
+ 7,
+ 8)
+
+Tree (1, ((2, 3), (4, (5, ((6, 7), 8))))) can be pprint'd as:
+(1,
+ ((2,
+   3),
+  (4,
+   (5,
+    ((6,
+      7),
+     8)))))
+
+Tree ((((1, 2), 3), 4), 5, 6, 7, 8) can be pprint'd as:
+((((1,
+    2),
+   3),
+  4),
+ 5,
+ 6,
+ 7,
+ 8)
+>>>

Task/Visualize-a-tree/Tcl/visualize-a-tree-1.tcl

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+package require struct::tree
+
+proc visualize_tree {tree {nameattr name}} {
+    set path {}
+    $tree walk [$tree rootname] -order both {mode node} {
+	if {$mode eq "enter"} {
+	    set s ""
+	    foreach p $path {
+		append s [expr {[$tree next $p] eq "" ? "  " : "\u2502 "}]
+	    }
+	    lappend path $node
+	    append s [expr {
+		[$tree next $node] eq "" ? "\u2514\u2500" : "\u251c\u2500"
+	    }]
+	    if {[$tree keyexists $node $nameattr]} {
+		set name [$tree get $node $nameattr]
+	    } else {
+		# No node name attribute; use the raw name
+		set name $node
+	    }
+	    puts "$s$name"
+	} else {
+	    set path [lrange $path 0 end-1]
+	}
+    }
+}

Task/Visualize-a-tree/Tcl/visualize-a-tree-2.tcl

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+# Sample tree to demonstrate with
+struct::tree t deserialize {root {} {} a 0 {} d 3 {} e 3 {} f 9 {} b 0 {} c 0 {}}
+visualize_tree t