### Re: Challenge: Dumping trees.

by hdb (Monsignor)
 on Sep 21, 2013 at 20:36 UTC ( #1055149=note: print w/replies, xml ) Need Help??

in reply to Challenge: Dumping trees.

I am not sure if I add a new approach as I have not studied all posts in this thread in much detail. My code is just a bit shorter and I think a pretty direct approach to the problem.

```use strict;
use warnings;

sub prepare {
my( \$subtree, \$level, \$col, \$graph ) = @_;
my \$lcol = 0;
if( ref(\$subtree) ) {
\$lcol = prepare( \$subtree->[0], \$level+1, \$col, \$graph );    # par
+se left side of tree, keep top position
\$lcol and \$graph->[\$level]->[\$_] = '_' for \$lcol..\$\$col-1;   # dra
+w horizontal line
\$graph->[\$level]->[\$\$col++] = '/';
\$lcol = \$\$col;                                               # new
+ root of the tree
\$graph->[\$level]->[\$\$col++] = '\\';
my \$rcol = prepare( \$subtree->[1], \$level+1, \$col, \$graph ); # par
+se right side of the tree, keep its top position
\$rcol and \$graph->[\$level]->[\$_] = '_' for \$lcol+1..\$rcol-1; # dra
+w horizontal line
} else {
\$graph->[\$level]->[\$\$col++] = \$subtree;                      # lea
+f
}
return \$lcol;                                                  # ret
+urn column of root
}

my \$root = do {
my \$r;
my @a = ( 'a'..'z', 1..9, 'A'..'Z' );
\$r = int( rand \$#a ), splice @a, \$r, 2, [ @a[ \$r, \$r+1 ]] while @a
+ > 1;
\$a[0];
};

my @graph;
my \$col = 0;
prepare( \$root, 0, \\$col, \@graph );
for my \$row ( @graph ) {
print \$_ // ' ' for @\$row;
print "\n";
}

UPDATE: Here is some sample output for a smaller tree:

```
_____/\_
+_
__________________________/\__
+/\__
____________________/\________                    /\   x
+   /\
__/\________               _____/\___________       v  w
+  y  z
__/\     _____/\__           /\__            __/\__
__/\   e   /\__     /\__       m   /\     _____/\    /\
__/\   d     f   /\   i   /\__       n  o   /\__    s  t  u
/\   c           g  h     j   /\            p   /\
a  b                          k  l              q  r

Replies are listed 'Best First'.
Re^2: Challenge: Dumping trees.
by BrowserUk (Pope) on Sep 21, 2013 at 21:52 UTC

On first blush, that appears to be astonishingly ... astonishing. Um. That's not good English is it. I'll try again.

After scant consideration, that appears to be remarkably ... remarkable. D'oh!

I will adapt it to produce my preferred, revised format -- contrast original format with my revised, preferred format so that I can compare like-for-like with my final version.

Then I'll get back to you.

Meantime, that's impressive!

Weirdly, I especially like the comments. If that sounds strange, trust me, it is even stranger, given that I (generally) hate comments.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

For that you require a left/right flag to indicate which side of a subtree you are in. The logic is probably even simpler:

```use strict;
use warnings;

use constant { LEFT => 0, RIGHT => 1 };

sub prepare {
my( \$subtree, \$lr, \$level, \$col, \$graph ) = @_;
if( ref(\$subtree) ) {
my \$lcol = prepare( \$subtree->[LEFT ], LEFT,  \$level+1, \$col, \$gra
+ph );
\$\$col+=2;
my \$rcol = prepare( \$subtree->[RIGHT], RIGHT, \$level+1, \$col, \$gra
+ph );
\$graph->[\$level]->[\$lcol] = '/';
\$graph->[\$level-1]->[\$_] = '_' for \$lcol+1..\$rcol-1;
\$graph->[\$level]->[\$rcol] = '\\';
return \$lr == LEFT ? \$rcol : \$lcol;  # intentionally the other way
+ round !!
} else {
\$graph->[\$level]->[\$\$col] = \$subtree;
return \$\$col;
}
}

my \$root = do {
my \$r;
my @a = ( 'a'..'z', 1..9, 'A'..'Z' );
\$r = int( rand \$#a ), splice @a, \$r, 2, [ @a[ \$r, \$r+1 ]] while @a >
+ 1;
\$a[0];
};

my @graph;
my \$col = 0;
prepare( \$root, LEFT, 1, \\$col, \@graph ); # need to start with \$level
+ = 1 !
for my \$row ( @graph ) {
print \$_ // ' ' for @\$row;
print "\n";
}

and it looks like this:

```                                                 _____________
_____________/             \_______
+__________
_____/             \_________   _/
+          \___________________________
_____________/     \_______     _/         \ / \    ___
+__________/                           \_________
_________/             \    _/       \_  / \___      4 5 6  _/
+          \_______                 ___/         \_
_/         \_____        o  _/ \_     _/ \ x /   \_          / \_
+       ___/       \_             _/   \_       _/ \
_/ \_     ___/     \_        / \ / \_  / \ w   y  _/ \_        7 / \_
+   ___/   \___    / \_          / \  _/ \_    / \ Z
/ \ / \  _/   \_   _/ \_      p q r / \ u v       / \ / \         8 /
+\ /   \_  /   \_  J / \___      Q R / \ / \_  X Y
a b c d / \_  / \ / \ / \_          s t           z 1 2 3           9
+A B  _/ \ F  _/ \   K /   \_        S T U / \
e / \ h i j k l / \
+    / \ E   / \ I     L  _/ \_            V W
f g           m n
+    C D     G H         / \ / \

+                        M N O P

UPDATE:

Replacing the 2 in line \$\$col+=2; with a larger number makes the tree wider which might be useful for readability.

Replacing the line \$graph->[\$level]->[\$\$col] = \$subtree; with \$graph->[\$level++]->[\$\$col] = \$_ for split //, \$subtree; will print leaf values vertically.

Very nice. Beautiful even. Makes mine look positively primitive :)

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

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