Visualize nested array

Question

You will be given a nested array. Your program has to visualize the array.

---

But.. How?

For example, let's assume we have a nested array, like [["1","2"],[["1","2"],"3"],"4",[[[["5"]]]],"6"].

This nested array can be visualised as:

->1
->2
-->1
-->2
->3
>4
---->5
>6

---

Examples

Input 1:
["Atom",["Proton",["Up Quark", "Up Quark", "Down Quark"], "Neutron", ["Up Quark", "Down Quark", "Down Quark"], "Electron"]]
Output 1:
>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Down Quark
-->Down Quark
->Electron

Input 2:
[["1","2"],["3","4"]]
Output 2:
->1
->2
->3
->4

---

Rules

• You may use string (or other types which work like a nested array) as input.
• The maximum level of "layers" is 2^32-1.

Answer 1

APL, 32 bytes

{1=≡⍺:⎕←⍺,⍨⍵↑1↓⍵/'->'⋄⍺∇¨⍵+1}∘0

Test:

      r
┌────┬─────────────────────────────────────────────────────────────────────────────────────────┐
│Atom│┌──────┬──────────────────────────────┬───────┬────────────────────────────────┬────────┐│
│    ││Proton│┌────────┬────────┬──────────┐│Neutron│┌────────┬──────────┬──────────┐│Electron││
│    ││      ││Up Quark│Up Quark│Down Quark││       ││Up Quark│Down Quark│Down Quark││        ││
│    ││      │└────────┴────────┴──────────┘│       │└────────┴──────────┴──────────┘│        ││
│    │└──────┴──────────────────────────────┴───────┴────────────────────────────────┴────────┘│
└────┴─────────────────────────────────────────────────────────────────────────────────────────┘
      {1=≡⍺:⎕←⍺,⍨⍵↑1↓⍵/'->'⋄⍺∇¨⍵+1}∘0 ⊢ r 
>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Down Quark
-->Down Quark
->Electron

Explanation:

• {...}∘0: run the following function with 0 bound to ⍵:
  • 1=≡⍺:: if the input has depth 1 (i.e. an array that does not contain other arrays):
    • ⍵/'->': create a string containing ⍵ -s and ⍵ >s,
    • 1↓: drop the first element,
    • ⍵↑: and take the first ⍵ elements. This results in a string containing ⍵-1 dashes and one >.
    • ⍺,⍨: append the input to it,
    • ⎕←: and output that to the screen
  • ⋄: otherwise,
    • ⍺∇¨⍵+1: add 1 to ⍵ and apply the function to each nested array

Answer 2

Mathematica, 58 57 56 bytes

Thanks to Greg Martin for saving 1 byte.

Thanks to ngenisis for saving 1 byte.

MapIndexed[Print[Table["-",Tr[1^#2]-1]<>">",#]&,#,{-1}]&

Answer 3

Java 7, 153 141 114 bytes

String r="";<T,S>S c(S s,T o){for(T x:(T[])o)if(x instanceof Object[])c("-"+s,x);else r+=s+">"+x+"\n";return(S)r;}

-39 bytes thanks to @Barteks2x

Explanation:

String r="";                         // Result String outside the method / on class-level
<T,S> S c(S s, T o){                 // Recursive Method with generic String and Object parameters and String return-type
  for(T x : (T[])o)                  //  Loop over the input-array
    if(x instanceof Object[])        //   If the current item is an array itself:
      c("-"+s, x);                   //    Recursive method-call with this array
    else                             //   Else:
      r += s+">"+x+"\n";             //    Append return-String with stripes String-input, ">", current item, and a new-line
                                     //  End of loop (implicit / single-line body)
  return (S)r;                       //  Return the result-String
}                                    // End of method

Test code:

Try it here.

class M{
  String r="";<T,S>S c(S s,T o){for(T x:(T[])o)if(x instanceof Object[])c("-"+s,x);else r+=s+">"+x+"\n";return(S)r;}

  public static void main(String[] a){
    M m = new M();
    System.out.println(m.c("", new Object[]{new Object[]{1,2},new Object[]{new Object[]{1,2},3},4,new Object[]{new Object[]{new Object[]{new Object[]{5}}}},6}));
    m.r = "";
    System.out.println(m.c("", new Object[]{"Atom",new Object[]{"Proton",new Object[]{"Up Quark","Up Quark","Down Quark"}},new Object[]{"Neutron",new Object[]{"Up Quark","Up Quark","Down Quark"}},"Electron"}));
  }
}

Output:

->1
->2
-->1
-->2
->3
>4
---->5
>6

>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Up Quark
-->Down Quark
>Electron

Answer 4

PHP, 77 74 73 bytes

4 bytes saved thanks @manatwork.

function f($a,$p=">"){foreach($a as$e)"$e"!=$e?f($e,"-$p"):print"$p$e
";}

recursive function, requires PHP 7.1 or newer for the negative string index.
^{"$e" is Array for arrays; so "$e"!=$e is the same as is_array($e).}

• start with prefix >
• prepend a - to the prefix for each level
• print prefix+element+newline for atoms

Answer 5

C99 (GCC), 201 187 140 112 109

f(char*a){for(long d=1,j;j=d+=*++a>90?92-*a:0;)if(*a<35){for(;j||*++a^34;)putchar(j?"->"[!--j]:*a);puts("");}}

expanded form:

f(char*a){
    for(long d=1,j;j=d+=*++a>90?92-*a:0;)
        if(*a<35){
            for(;j||*++a^34;)putchar(j?--j?45:62:*a);
            puts("");
        }
}

This takes a string in the correct format and terminates when finding the last matching ].

It doesn't use recursion and uses long types to actually achieve the second rule: 2^32-1 levels. Most scripting languages have a limited recursion depth or simply crash on stack overflow.

I'm not used to golf in C any help is appreciated :)

Thanks at bolov for his tips ! Specially thanks to Titus who's always up for a good round of golfing (even in C) !

Another two bytes saved by the fact that we can finish once we match the last ] and don't need to match a null char.

It can be tested at Wandbox.

Answer 6

JavaScript (ES6), 58 51 bytes

f=(a,s='>')=>a.map(e=>e.map?f(e,'-'+s):s+e).join`
`

Edit: Saved 7 bytes when @Arnauld pointed out that I could combine my two approaches.

Answer 7

PHP, 129 123 112 109 95 93 91 bytes

for(;a&$c=$argn[++$i];)$c<A?$c<"-"?a&$s?$s=!print"$p>$s
":0:$s.=$c:$p=substr("---$p",$c^i);

iterative solution takes string from STDIN:
Run with echo '<input>' | php -nR '<code>' or test it online.

breakdown

for(;a&$c=$argn[++$i];)     // loop $c through input characters
    $c<A                        // not brackets?
        ?$c<"-"                     // comma or quote?
            ?a&$s?$s=!print"$p>$s\n":0  // if $s not empty, print and clear $s
            :$s.=$c                     // digit: append to $s
        :$p=substr("---$p",$c^i)    // prefix plus or minus one "-"
;

Happy that the numbers are in quotes; so I only need one action at a time.

ASCII fiddling

char    ascii   binary/comment
 "       34
 ,       44
 [       91     0101 1011
 ]       93     0101 1101

 A       65     $c<A    true for comma, quote and digits
 -       45     $c<"-"  true for comma and quote

                =0011 1010 -> 50 -> "2"
i^"["   105^91  ^0101 1011
 i      105      0110 1001
i^"]"   105^93  ^0101 1101
                =0011 0100 -> 52 -> "4"

Adding 3 dashes to $p and removing 2 for [, 4 for ] adds one for [ and removes one for ].

Answer 8

Python 2, 65 64 bytes

f=lambda o,d=0:o<''and'\n'.join(f(e,d+1)for e in o)or'-'*d+'>'+o

Right now my answer consistently starts with no dashes, so ["foo", "bar"] is:

>foo
>bar

Answer 9

Perl 5, 55 bytes

53 bytes of code + -nl flags.

/"/?print"-"x~-$v.">$_":/]/?$v--:$v++for/]|\[|".*?"/g

Try it online!

Not optimal for regex because of some edgy cases that could potentially occur (in particular, if an element of the array contains brackets inside).
A recursive anonymous function would be barely longer though (61 bytes):

sub f{my$v=pop;map{ref?f(@$_,$v+1):"-"x$v.">$_"}@_}sub{f@_,0}

Try it online!

But the way Perl deals with parameters isn't optimal for golfing functions: no optional parameters means I have to do a second function (anonymous) calling the first one, and I have to explicitly get the last parameter with that long my$v=pop.

Answer 10

Ruby, 49 45 46 bytes

f=->c,p=?>{c.map{|x|x==[*x]?f[x,?-+p]:p+x}*$/}

Example:

puts f[["Atom",["Proton",["Up Quark", "Up Quark", "Down Quark"], "Neutron", ["Up Quark", "Down Quark", "Down Quark"], "Electron"]]]

>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Down Quark
-->Down Quark
->Electron

Explanation:

Recursive function: if x==[*x] then x is an array, and we iterate over it. If not, indent it.

Answer 11

Haskell, 104 bytes

l@(x:y)#(a:m)|[(h,t)]<-reads$a:m=y++h++l#t|a<'#'=l#m|a<'-'='\n':l#m|a>'['=y#m|q<-'-':l=q#m
l#_=""
(">"#)

Haskell doesn't have nested lists with different depths, so I have to parse the input string on my own. Luckily the library function reads can parse Strings (i.e. "-enclosed char sequence), so I have a little help here.

Usage example:

*Main> putStrLn $ (">"#) "[[\"1\",\"2\"],[\"3\",\"4\"]]" 
->1
->2
->3
->4

Try it online!.

How it works:

The function # goes through the string char by char and keeps the nesting level (the first parameter l) as a string of - with a final >. If the head of the list can be parsed as a String, take l and the String followed by recursive call with the String removed. If the first char is a Space, skip it. If it's a ,, take a newline and go on, if it's ], lower the nesting level and go on and else (only [ left) raise the nesting level and go on. Recursion ends with the empty input string. The main function (">"#) sets the nesting level to ">" and calls #.

Answer 12

SWI-Prolog, 115 bytes

p(L):-p(L,[>]).
p([],_):-!.
p([H|T],F):-p(H,[-|F]),p(T,F),!.
p(E,[_|F]):-w(F),w([E]),nl.
w([]).
w([H|T]):-write(H),w(T).

Line breaks added for readability only, not included in byte count.

p predicate recursively traverses the arrays, adding a '-' to the prefix F when moving a level deeper. w is used to write the prefix array as well as the actual element to the output.

Example:

?- p(["Atom",["Proton",["Up Quark", "Up Quark", "Down Quark"], "Neutron", ["Up Quark", "Down Quark", "Down Quark"], "Electron"]]).
>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Down Quark
-->Down Quark
->Electron

Answer 13

Batch, 249 bytes

@echo off
set/ps=
set i=
:t
set t=
:l
set c=%s:~,1%
set s=%s:~1%
if "%c%"=="[" set i=-%i%&goto l
if not "%c%"=="]" if not "%c%"=="," set t=%t%%c%&goto l
if not "%t%"=="" echo %i:~1%^>%t%
if "%c%"=="]" set i=%i:~1%
if not "%s%"=="" goto t

Annoyingly Batch has trouble comparing commas. Sample run:

[Atom,[Proton,[Up Quark,Up Quark,Down Quark],Neutron,[Up Quark,Down Quark,Down Quark],Electron]]
>Atom
->Proton
-->Up Quark
-->Up Quark
-->Down Quark
->Neutron
-->Up Quark
-->Down Quark
-->Down Quark
->Electron

Answer 14

Retina, 63 54 52 bytes

Saved 2 bytes thanks to Martin Ender

.*?".*?"
$`$&¶
T`[] -~`-]_`.(?=.*".*")
-]

-"
>
T`]"

Try it online!

Explanation

.*?".*?"
$`$&¶

First, the array is broken up by replacing each quoted string with everything that came before it, plus itself, plus a newline. By breaking it up like this, it's possible to find the unmatched opening brackets before each string.

T`[] -~`-]_`.(?=.*".*")

This transliteration will replace [ with -, leave ] unchanged, and delete every other character ( -~ is all printable ASCII). However, it only replaces characters appearing before the final string on each line.

-]

Next all instances of -] are removed. These correspond to matching bracket pairs, and we only want unmatched brackets. After these are removed, each line has a number of -s equal to how many unmatched opening brackets came before it.

-"
>

The last - before a " is replaced with >, to form the arrows.

T`]"

Finally, all remaining ]s and "s are deleted.

Answer 15

Röda, 54 bytes

f d=""{{|n|{n|f d=`$d-`}if[n is list]else[`$d>$n
`]}_}

Try it online!

It's a function that reads the input array from the stream. For each item, it either calls itself recursively or prints the item.

Answer 16

Python 3, 80 Bytes

Python's lambdas support recursion it seems, who knew ?

p=lambda l,d=1:[p(i,d+1)if isinstance(i,list)else print("-"*d+">"+i)for i in l]

This is a counter/compliment to orlp's answer.

Answer 17

Groovy, 92 bytes

x={a,b->if(a instanceof List){a.each{x(it,b+1)}}else{y(a,b)}};y={a,b->println("-"*b+">$a")};

Answer 18

Stacked, 27 bytes

[@.1-'-'*\'>'\,,out]deepmap

Try it online!

Takes input from the top of the stack and leaves output on STDOUT. This is simple as doing a depth map, repeating - d times, concatenating with '>' and the element itself.

Answer 19

Gema, 63 characters

\A=@set{i;-1}
[=@incr{i}
]=@decr{i}
"*"=@repeat{$i;-}>*\n
,<s>=

Like the other parsing solutions, assumes there will be no escaped double quotes in the strings.

Sample run:

bash-4.3$ gema '\A=@set{i;-1};[=@incr{i};]=@decr{i};"*"=@repeat{$i;-}>*\n;,<s>=' <<< '[["1","2"],[["1","2"],"3"],"4",[[[["5"]]]],"6"]'
->1
->2
-->1
-->2
->3
>4
---->5
>6

Answer 20

jq, 70 67 characters

(67 64 characters code + 3 characters command line option)

def f(i):if type=="array"then.[]|f("-"+i)else i+. end;.[]|f(">")

Sample run:

bash-4.3$ jq -r 'def f(i):if type=="array"then.[]|f("-"+i)else i+. end;.[]|f(">")' <<< '[["1","2"],[["1","2"],"3"],"4",[[[["5"]]]],"6"]'
->1
->2
-->1
-->2
->3
>4
---->5
>6

On-line test