You could build a oneliner out of this multistage process:
d =: 0 1 2 2 1 1 2 2 3
indent =: ' ' <@(#"0 1~) 0 >. <: +/ (i.@# </~ <:@# - (i. ~.)@|.)d
branch =: a: , (1 ,~ }: 0 = 2 -/\&.|. d) <@{ 2 2 $ '|-+-'
infix =: (<@:,&>/)"1 indent,.branch
prefix =: '| ' <@#"0 1~ d - , -:@$@> infix
;"1 prefix ,. infix ,. <'o'
which gives the desired result for d
I didn’t test on larger/more complex trees, though.
Am 07.08.20 um 15:19 schrieb ethiejiesa via Programming:
Do you know a slick way of pretty-printing a tree given its depth vector
representation?
A vector represents a tree if and only if it satisfies the following:
NB. Tree valid? First node is root node (depth 0), only one root node,
NB. and all nodes are exactly one deeper than their parent
tv=: 0&=@{. *. *./@(>&0)@}. *. 1 *./@:>: +/\^:_1
The goal is to produce a nice visualization given a valid depth vector. For
example, given (d=: 0 1 2 2 1 1 2 2 3), something like this would be ideal:
o
|-o
| |-o
| +-o
|-o
+-o
|-o
+-o
+-o
About the best I can do in a single line is this:
NB. Tree print
tp=: (, LF&,)/@({&' |o-')@((3&*@=/ |:@}.@(,/)@(,:"1&|:) 2&*@=/ +. >/)
~.)
tp d
o
|-o
| |-o
| | |-o
|-o
| |-o
| | |-o
|-o
| |-o
| | |-o
Trimming the branches, however, is giving me a lot of grief. Can you do better?
I am looking for terse one-liners but am open to alternative visualizations.
Producing segments of "trimmed branches" is a nice little sub-problem. It
corresponds to finding finding "catenaries", i.e. runs of integers capped on
the left and right by n, where the intervening integers "droop below" n, i.e.
satisfy (>:n).
Looking forward to your ideas!
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