Indented List to Multidimensional Array

Converting Julia nested list to multidimensional array

hcat works fine:

julia> hcat([[1,2],[4,5]]...)
2×2 Matrix{Int64}:
 1  4
 2  5

The thing is that vectors are column-vectors in Julia (unlike in NumPy, for example), so you should horisontally concatenate them to get the matrix.

If you use vcat, you'll stack them on top of each other, getting one tall vector:

julia> vcat([[1,2],[4,5]]...)
4-element Vector{Int64}:
 1
 2
 4
 5

Indented list to multidimensional array

As it's still unclear if you're trying to read from some given structure (html-dom) or from the given string as plain text, I assumed it's the string you're trying to parse. If so, try:

<?php
$list =
'Home
Products
    Product 1
        Product 1 Images
    Product 2
        Product 2 Images
    Where to Buy
About Us
    Meet the Team
    Careers
Contact Us';

function helper($list, $indentation = '    ') {
  $result = array();
  $path = array();

  foreach (explode("\n", $list) as $line) {
    // get depth and label
    $depth = 0;
    while (substr($line, 0, strlen($indentation)) === $indentation) {
      $depth += 1;
      $line = substr($line, strlen($indentation));
    }

    // truncate path if needed
    while ($depth < sizeof($path)) {
      array_pop($path);
    }

    // keep label (at depth)
    $path[$depth] = $line;

    // traverse path and add label to result
    $parent =& $result;
    foreach ($path as $depth => $key) {
      if (!isset($parent[$key])) {
        $parent[$line] = array();
        break;
      }

      $parent =& $parent[$key];
    }
  }

  // return
  return $result;
}

print_r(helper($list));

Demo: http://codepad.org/zgfHvkBV

Convert nested list to 2d array

There is no simple builtin way to do what you want because your list.toArray() can return only array of elements stored in list which in your case would also be lists.

Simplest solution would be creating two dimensional array and filling it with results of toArray from each of nested lists.

String[][] array = new String[list.size()][];

int i = 0;
for (List<String> nestedList : list) {
    array[i++] = nestedList.toArray(new String[0]);
}

(you can shorten this code if you are using Java 8 with streams just like Alex did)

How to convert nested List into multidimensional array?

This is the way that someone suggested to solved for String type. Cast2(List<?>) returns the multidimensional array. It may be generalized to use the class type as parameter. Thank you for your comments.

static int dimension2(Object object) {

    int result = 0;
    if (object instanceof List<?>) {

        result++;
        List<?> list = (List<?>) object;
        for (Object element : list) {
            if (element != null) {
                result += dimension2(element);
                break;
            }
        }
    }

    return result;
}

static Object cast2(List<?> l) {

    int dim = dimension2(l);
    if (dim == 1) {
        return l.toArray(new String[0]);
    }

    int[] dims = new int[dimension2(l)];
    dims[0] = l.size();
    Object a = Array.newInstance(String.class, dims);
    for (int i = 0; i < l.size(); i++) {

        List<?> e = (List<?>) l.get(i);
        if (e == null) {
            Array.set(a, i, null);
        } else if (dimension2(e) > 1) {
            Array.set(a, i, cast2(e));
        } else {
            Array.set(a, i, e.toArray(new String[0]));
        }
    }
    return a;
}

Convert nested lists to multidimensional array in R, preserving slice order

Here is a generalization of the transpose (t) function for multi-dimensional arrays:

tarray <- function(x) aperm(x, rev(seq_along(dim(x))))

Then you can define ar as follows:

ar <- tarray(array(unlist(nestlist), c(4, 3, 2)))
ar[2,2,3]
# [1] "223"

Create nested list from Multidimensional Array

You should use recursion:

First the array in 'php' syntax:

<?php
$a=array (
    '0' => array (
        'id' => 1,
        'title' => "Title 1",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '1' => array (
        'id' => 2,
        'title' => "Title 2",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '2' => array (
        'id' => 3,
        'title' => "Title 3",
        'parent_id' => 2,
        'depth' => 1
    ),
    '3' => array (
        'id' => 4,
        'title' => "Title 4",
        'parent_id' => 2,
        'depth' => 1
    ),
    '4' => array (
        'id' => 5,
        'title' => "Title 5",
        'parent_id' => 'NULL',
        'depth' => 0
    ),
    '5' => array (
        'id' => 6,
        'title' => "Title 6",
        'parent_id' => 4,
        'depth' => 0
    )
);

Here the code:

$level = 'NULL';

function r( $a, $level) {
   $r = "<ol>";
   foreach ( $a as $i ) {
       if ($i['parent_id'] == $level ) {
          $r = $r . "<li>" . $i['title'] . r( $a, $i['id'] ) . "</li>";
       }
   }
   $r = $r . "</ol>";
   return $r;
}

print r( $a, $level );

?>

The results:

<ol><li>Title 1<ol></ol></li><li>Title 2<ol><li>Title 3<ol>
</ol></li><li>Title 4<ol><li>Title 6<ol></ol></li></ol></li></ol></li><li>Title 5
<ol></ol></li></ol>

1. Title 1\n
2. Title 2\n
   1. Title 3\n
   2. Title 4\n
      1. Title 6\n
3. Title 5\n

EDITED AFTER CHECK AS SOLUTION

To avoid empty leafs:

function r( $a, $level) {
   $r = '' ;
   foreach ( $a as $i ) {
       if ($i['parent_id'] == $level ) {
          $r = $r . "<li>" . $i['title'] . r( $a, $i['id'] ) . "</li>";
       }
   }
   return ($r==''?'':"<ol>". $r . "</ol>");
}

Nested list or two dimensional array in Python

You can use collections.Counter to count each IP-{number} line from the file:

from collections import Counter

with open("test.txt") as f:
    ip_counts = Counter(line.strip() for line in f)
    # Counter({'IP-4': 3, 'IP-2': 2, 'IP-1': 1, 'IP-7': 1})

    for ip_address, count in ip_counts.items():
        print("IP address %s occured %d times" % (ip_address, count))

Output:

IP address IP-1 occured 1 times
IP address IP-4 occured 3 times
IP address IP-7 occured 1 times
IP address IP-2 occured 2 times 

You can also use map() to count the lines as well if you prefer:

ip_counts = Counter(map(str.strip, f))

Note: str.strip() is used here to strip whitespace from the keys, such as converting 'IP-1\n' to IP-1. This allows easier access to the keys in the future since you don't need to include whitespace.

If you want the maximum count, I would use max() with operator.itemgetter():

print(max(ip_counts.items(), key=itemgetter(1)))
# ('IP-4', 3)

Which returns the maximum tuple using the counts at index 1.

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