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I have a number of records like these: 

2011-01-01, a, 1
2011-01-01, c, 5
2011-01-01, d, 3
2011-01-02, a, ...

The first value is a date, the second is a string (can be a or b or c or d), and the third is a number.

How can I add all the records into an array in PHP, and the array's structure is like:

array('2011-01-01' => array('a' => '1','b' => '0','c' => '5','d' => '3'), '2011-01-02' => ... ,)

so that the date variable is an index, and the key is a four-element array, each element is the corresponding record number (third value)?

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How are initial records actually stored? As an array structure, in a file, or in a database? – cbuckley Jan 10 '12 at 0:13
read from database, stored as array – xuc Jan 10 '12 at 0:16

5 Answers

up vote 1 down vote accepted

How about this (assuming the format of your input data):

$input = array(
    array('2011-01-01', 'a', '1'),
    array('2011-01-01', 'c', '5'),
    array('2011-01-01', 'd', '3'),
    array('2012-01-01', 'a', '1')
);

// used to populate the default strings (a b c d)
$strings = range('a', 'd');
$stringDefaults = array_combine($strings, array_fill(0, count($strings), '0'));

$output = array();

foreach ($input as $row) {
    list ($date, $string, $number) = $row;

    if (!isset($output[$date])) {
        $output[$date] = $stringDefaults;
    }

    $output[$date][$string] = $number;
}

echo json_encode($output);
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Won't that json_encode output the array with brackets not braces? – AlienWebguy Jan 10 '12 at 0:27
See codepad.org/7JIYcFhi; the arrays are associative so braces will be used. In any case, the JSON representation in the question seems only incidental to describing the structure, rather than the intended output, but I included it anyway. – cbuckley Jan 10 '12 at 0:30
up vote 1 down vote

Assuming this is a big string, split it on the lines, then on the commas. For each line, test if the date already exists as a key, and if it does, add to it, otherwise, create it:

$string = "2011-01-01, a, 1
2011-01-01, c, 5
2011-01-01, d, 3
2011-01-02, a, 1";

// Array to hold it all...
$array = array();
$lines = explode("\n", $string);
foreach ($lines as $line) {
  // Explode the line on the comma into 3 variables
  list($date, $key, $num) = explode(",", $line);
  $date = trim($date);
  $key = trim($key);
  $num = intval($num);

  // Create an array key for the current $date if it doesn't exist
  // as a new array
  if (!isset($array[$date])) $array[$date] = array();

  // And assign the number with the corresponding letter key to the array
  // for this date.
  $array[$date][$key] = $num;
}
share|improve this answer
+1 - But don't forget to trim. – Joseph Silber Jan 10 '12 at 0:17
@JosephSilber Thanks, and edited. – Michael Berkowski Jan 10 '12 at 0:19
I think this misses the requirement to have "b": "0" as part of the output (i.e. all possible strings a, b, c, d should show with a default number of 0)? – cbuckley Jan 10 '12 at 0:26
up vote 1 down vote 
$records = array(
    0 => array('2011-01-01', 'a', '1'),
    1 => array('2011-01-01', 'c', '5'),
    2 => array('2011-01-01', 'd', '3'),
    3 => array('2012-01-01', 'a', '1')
);

$tmp_arr   = array();
$tmp_dates = array();
$tmp_str   = '';

foreach ($records as $record) {
    $tmp_arr[$record[0]][$record[1]] = $record[2];
}

foreach ($tmp_arr as $date => $record) {
    $tmp_params = array();
    foreach ($record as $key => $val) {
        $tmp_params[] = $key . ':' . $val;
    }
    $tmp_dates[] = $date . ':' . '{' . implode(',', $tmp_params) . '}';
}

$tmp_str = '{' . implode(',', $tmp_dates) . '}';

echo $tmp_str; // {2011-01-01:{a:1,c:5,d:3},2012-01-01:{a:1}}
share|improve this answer
As with Michael's answer, the OP seems to suggest each date array should be a 4-element array itself, with a default number of 0 if that line is not present in the input. – cbuckley Jan 10 '12 at 0:27
up vote 0 down vote

Provided your data is in a text file (.txt):

$records = file_get_contents("filename.txt");

// $records will be equal to the following: (on windows, it would be \r\n instead of just \n)
// $records = "2011-01-01, a, 1\n2011-01-01, c, 5\n2011-01-01, d, 3\n 2011-01-02, d, 3";

$records = explode("\n", $records);

$output = array();

for ($i = 0; $i < count($records); $i++) {

    $rec = explode(",", $records[$i]);
    $key = $rec[0];

    if ($output[$key] == null)
        $output[$key] = array();

    if (!array_key_exists("a", $output[$key]))
        $output[$key]["a"] = 0;

    if (!array_key_exists("b", $output[$key]))
        $output[$key]["b"] = 0;

    if (!array_key_exists("c", $output[$key]))
        $output[$key]["c"] = 0;

    if (!array_key_exists("d", $output[$key]))
        $output[$key]["d"] = 0;

    $elem = trim($rec[1]);
    $value = trim($rec[2]);
    $output[$key][$elem] = intval($value);

}

var_dump($output);
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oh i just read in one of your comments that you are reading from the db and storing in an array, otherwise the format you posted initially looked like a text stream :) let me know if you have trouble translating above code to read from an array instead of a text file. – Software Guy Jan 10 '12 at 0:50
up vote 0 down vote

Ok, here's what you do.

$records = array(
    0 => array('2011-01-01', 'a', '1'),
    1 => array('2011-01-01', 'c', '5'),
    2 => array('2011-01-01', 'd', '3'),
    3 => array('2012-01-01', 'a', '1')
);

$dateArray = array();
$baseArray = array('a' => '0','b' => '0','c' => '0','d' = '0');

foreach($records as $record)
{
     $dateArray[$record[0]][$record[1]] = $record[2];  //You could actually do this while pulling in the info from the DB
}

foreach($dateArray as $date => $array)
{
     $missingArray = array_diff_key($array,$baseArray);  //Determine what keys are missing using the base array, get keys and default values
     $dateArray[$date] = array_merge($array,$missingArray);  //Merge the missing parts with the current array
}

Note, parts copied for time from other posts.

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