Problem with arrays and multiple values per key

[Epimetheus1980]

I am very grateful for any input. I have a field in a database that contains references (pattern: authorYYYY), such as the following string:

 

"authorA1989; authorB1978a; authorB1984; authorC1999; authorC2000a; authorC2000b; authorC2002; authorD2009"

 

What I want is an output as the following in order to create a proper bibliography (therefore accessing another table and picking out the respective reference details): 

 

authorA

   1989

authorB

   1978a

   1984

authorC

   1999

   2000a

   2000b

   2002

authorD

   2009

 

I somewhat fail to group the values (years) per author. I know that keys are unique, but is there a way to work around this?

 

Many thanks for any help! 

[cyberRobot]

You could create an associative array where "authorA", "authorB", etc. are the keys. Then just add the years using code similar to this:

$authorArray['authorA'][] = 1989;

[Epimetheus1980]

Thank you. Although this makes sense to me, I am not sure about filling the array. Here is my current code. I do not know how to implement the associative array with the year-values. 

$arr = array();

foreach(explode(';', $string) as $pair)
        {
	$author = preg_replace("/([A-Za-z]*)([0-9]*[a-z]?)/", "$1", $pair);
	$year = preg_replace("/([A-Za-z]*)([0-9]*[a-z]?)/", "$2", $pair);

        $arr[$author] = null;		

        }       
	
	foreach($arr as $key=>$val) {
		echo "<p>" . $key . "</p>";
	}

[ginerjm]

Backing up for a bit. Your first post indicates you have a db field that contains multiple values. You might solve your problem if you simply followed the rules of a properly structure database. Normalization (look it up) means you never put multiple discrete values into one field, but rather put them into separate records of a separate table. In your case that means that this:

 

[field1]

authorA1989; authorB1978a; authorB1984; authorC1999; authorC2000a; authorC2000b; authorC2002; authorD2009

 

being in one field of a table would become multiple records in a separate table:

 

[field1]

authorA1989

authorB1978a

authorB1984

authorC1999

authorC2000a

authorC2000b

authorC2002

authorD2009

 

where this table is linked back to the first table by some id value in the first table.

 

You really need to understand this and implement it.

[cyberRobot]

Thank you. Although this makes sense to me, I am not sure about filling the array. Here is my current code. I do not know how to implement the associative array with the year-values.

 

You could try something like this (note that the code is untested):

<?php
$arr = array();
 
foreach(explode(';', $string) as $pair) {
    $author = preg_replace("/([A-Za-z]*)([0-9]*[a-z]?)/", "$1", $pair);
    $year = preg_replace("/([A-Za-z]*)([0-9]*[a-z]?)/", "$2", $pair);
 
    //IF THIS IS THE FIRST ENTRY FOR THE CURRENT AUTHOR, INITIALIZE YEAR ARRAY
    if(!isset($arr[$author])) {
        $arr[$author] = array();
    }
 
    //ADD CURRENT YEAR
    $arr[$author][] = $year;
}       
 
foreach($arr as $key=>$val) {
    echo "<p>" . $key . "</p>";
    echo implode('<br>', $val);
}
?>

[Epimetheus1980]

Thank you. That's all already implemented. I just simplified it by using a string similar to the field in Table 1. My problem was that I didn't understand how to assign the values (years) to the respective keys (authors). 

Edited January 13, 2015 by Epimetheus1980

[Barand]

If you are going to normalize as ginerjm recommended then do it properly and not have multiple values in a single field.

 

"AuthorA2000a" is 3 separate fields viz. | Name | Year | Sequence |

 

You would store publications in separate table from the Author table and store the authorID as a foreign key

author
+----------+-------------------+
| authorID | name              |
+----------+-------------------+
|   1      | AuthorA           |
|   2      | AuthorB           |
+----------+-------------------+
     |
     |
     +-------------------------------------+
                                           |
                    publication            |
                    +---------+-------+----------+------------+
                    | pubID   |  year | authorID | pubname    |
                    +---------+-------+----------+------------+
                    |   1     | 2000  |    1     | pub 1      |
                    |   2     | 2000  |    1     | pub 2      |
                    |   3     | 2001  |    1     | pub 3      |
                    |   4     | 2000  |    2     | pub 4      |
                    |   5     | 2001  |    2     | pub 5      |
                    |   6     | 2002  |    2     | pub 6      |
                    |   7     | 2002  |    2     | pub 7      |
                    +---------+-------+----------+------------+