Implode a Column of Values from a Two Dimensional Array

Return single column from a multi-dimensional array

Quite simple:

$input = array(
  array(
    'tag_name' => 'google'
  ),
  array(
    'tag_name' => 'technology'
  )
);

echo implode(', ', array_map(function ($entry) {
  return $entry['tag_name'];
}, $input));

http://3v4l.org/ltBZ0

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and new in php v5.5.0, array_column:

echo implode(', ', array_column($input, 'tag_name'));

How can I implode() only one column from a multidimensional array?

I like array_column() but if you don't have PHP >= 5.5.0:

$list = implode(',', array_map(function($v) { return $v[1]; }, $data['sales']));

Or with the foreach:

foreach ($data['sales'] as $row) {
    $list[] = $row[1];
}
$list = implode(',', $list);

Easiest way to implode() a two-dimensional array?

This modifies your array using array_map, but probably for the better by turning it into a 1D array of tag_id's. Then you can just use implode like normal:

$arr = array_map(function($el){ return $el['tag_id']; }, $arr);
$str = implode(',', $arr);

If you don't want to modify your array than you can just do this:

$str = implode(',', array_map(function($el){ return $el['tag_id']; }, $arr));

Codepad Demo

Best way to implode multidimensional array

If it is a two dimensional array and would like to output all elements, you could use a foreach loop and output the implode of each like so:

$mainArray = [
    [4],
    [3, 4],
    [2, 30, 43, 65, 53, 634]];

foreach($mainArray as $key => $secArray){
    echo implode('-', $secArray) . '<br/>';
}

PHP Implode

Notice the return type of implode is a string.

Multidimensional Array PHP Implode

Update for PHP 5.5

PHP 5.5 introduces array_column which is a convenient shortcut to a whole class of array_map usage; it is also applicable here.

$ids = array_column($communications, 'id');
$output = implode(',', $ids);

Original answer

You need to make an array of just ids out of your array of communications. Then the implode would be trivial.

Hint: the function for that is array_map.

Solution:

Assumes PHP 5.3, otherwise you 'd have to write the callback as a string.

$ids = array_map(function($item) { return $item['id']; }, $communications);
$output = implode(',', $ids);

Implode a column of values from a two dimensional array

Simplest way, when you have only one item in inner arrays:

$values = array_map('array_pop', $array);
$imploded = implode(',', $values);

EDIT: It's for version before 5.5.0. If you're above that, see better answer below :)

Implode Multidimensional Array Keys and Values

You can just use array_keys and array_column:

$dates = implode(',', array_keys($output));
$data_values = implode(',', array_column($output, 'data_values'));

Demo on 3v4l.org

joining 2 dimensional array by columns

Instead of instantiating multiple arrays, you can just work with another two-dimensional array.

Here's a quick pass at an implementation (it could use more error checking, e.g. assumes all of the inner arrays in the input are the same length):

package main

import (
    "fmt"
)

func transpose(input [][]int) [][]int {
    result := make([][]int, len(input[0]))
    for _, row := range(input) {
        for j, value := range(row) {
            result[j] = append(result[j], value)
        }
    }
    return result
}

func main() {
    input := [][]int{{1,2,3,4}, {2,3,4,5}, {3,4,5,6}}
    result := transpose(input)
    
    fmt.Println(input)
    fmt.Println(result)
}

Output:

[[1 2 3 4] [2 3 4 5] [3 4 5 6]]
[[1 2 3] [2 3 4] [3 4 5] [4 5 6]]

Go Playground

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