How to create dynamic arrays and process it using php

Question

I want to create a dynamic array and process the data inside the array. Example:

a) If have 2 as digit input value, then it must create 2^2 = 4 arrays with 2 elements each. These elements are in form of binary (2 elements) => 00, 01, 10, 11

[pre]
Array1[] = {0, 0};
Array2[] = {0, 1};
Array3[] = {1, 0};
Array4[] = {1, 1};
[/pre]

b) If i 3 as digit input value, then it must create 2^3 = 8 arrays with 3 elements each. These elements are in form of binary (3 elements) => 000, 001, 010, 011, 100, 101, 110, 111

[pre]
Array1[] = {0, 0, 0};
Array2[] = {0, 0, 1};
Array3[] = {0, 1, 0};
Array4[] = {0, 1, 1};
Array5[] = {1, 0, 0};
Array6[] = {1, 0, 1};
Array7[] = {1, 1, 0};
Array8[] = {1, 1, 1};
[/pre]

Then i want to use this Array elements to calculate how many presence of "000" to "111" in a mysql table. The table has only 2 rows: id (auto_increment) and value (0/1). Example of searching for "101" in the table:

[pre]
id | value
----------
1  |   1
2  |   1   --
3  |   0    |  => (1)
4  |   1   --
5  |   0     | => (2)
6  |   1   -- 
7  |   0
8  |   0
9  |   1
10 |   1
.. |   ..
.. |   ..
5000 |  1  --
5001 |  0    |  => (n)
5002 |  1  --
5003 |  1
...  |  ...
[/pre]

A friend (Barmar) gave a solution in mysql to get how many "101" presence in the table (this is for : Array6[] = {1, 0, 1}; as example) , by using this code :

[pre]
select count(*) match_count
from TheTable t1
join TheTable t2 on t1.id+1 = t2.id
join TheTable t3 on t1.id+2 = t3.id
where t1.value = 1 and t2.value = 0 and t3.value = 1
[/pre]

My Questions :
1) How to make the 8 arrays that hold the elements {0,0,0} ... {1,1,1} for an input = 3?
2) How to make the "FOR" routine for these 8 arrays to search for the pattern inside mysql table ? I tried this below, but the result was wrong ....

[pre]
....
for ($i=1; $i<=8; $i++) {    // this is 2^3 = 8 arrays
  for ($k=0; $k<3; $k++) {
    $element$k = Array$i[$k];  // get each array elements (3 elements in each array)
  }
  $result = select count(*) match_count
        from TheTable t1
        join TheTable t2 on t1.id+1 = t2.id
        join TheTable t3 on t1.id+2 = t3.id
        where t1.value = $element$k and t2.value = $element$k and t3.value =  $element$k;  // these values must change for every array ....

       $query = mysql_query("INSERT INTO theResult(binary,presence) VALUES("'.$element$k.'","'.$result.'") ");

} // end of for
[/pre]

I expect to see this at mysql table "theResult" :

[pre]
binary  | presence
--------------------
000     | 21
001     | 18
010     | 32
011     | 11
100     | 44
101     | 17
110     | 8
111     | 25
[/pre]

But it doesn't happen like that ... :( Please help. Thank you

You're mixing php with SQL...

Marty McVry
– Marty McVry

2013-09-08 17:26:07 +00:00
Commented Sep 8, 2013 at 17:26 — Marty McVry
– Marty McVry, Commented Sep 8, 2013 at 17:26

zavg · Accepted Answer · 2013-09-10 14:22:41Z

1

The code for your exotic 1st problem is:

$N = 3;

for($i = 0; $i < pow(2,$N); $i++)
    ${"Array".$i} = str_split(str_pad(decbin($i), $N, '0', STR_PAD_LEFT));

Now $Array1, $Array2, ..., $Array8 consist of desired subarrays with binary values.

For example, value for $Array5 is

array(3) { [0]=> string(1) "1" [1]=> string(1) "0" [2]=> string(1) "1" }

The code is universal for natural Ns.

P.S.: It is much more better to use regular PHP array $arr[$i] instead of surrogate array ${"Array".$i}.

edited Sep 10, 2013 at 14:22

answered Sep 8, 2013 at 17:39

zavg

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12 Comments

user2758001 Over a year ago

Thank you zavg. Can you give me a clue how to get the array elements? for ($i=0; $i< pow(2,$N), $i++) { for ($k=0; $k<$N; $k++) { $getElement.$k = $Array.$i[$k]; } $result = select count(*) match_count from TheTable t1 join TheTable t2 on t1.id+1 = t2.id

join TheTable t3 on t1.id+2 = t3.id where t1.value = $getElement.$k and t2.value = $getElement.$k and t3.value = $getElement.$k; // wrong here ? $getElement.$k will hold the same value ?

...... }

user2758001 Over a year ago

Hi zavg, i think i can use "Foreach" instead of "for" routine in mysql query .... thank you

user2758001 Over a year ago

Hi zavg, i tried at LAMP:

print("<table><tr><td colspan=6><B>Result</B></td></tr>");    $N=3;    for($i = 0; $i < pow(2,$N); $i++) {     ${"myArray".$i} = str_split(str_pad(decbin($i), $N, '0', STR_PAD_LEFT));     echo('<tr><td colspan=6><B>3digit myArray: '.${"myArray".$i}.' </B></td></tr>');     }     print("</table>");

And as result i got this :

3digit myArray: Array      3digit myArray: Array      3digit myArray: Array      3digit myArray: Array      3digit myArray: Array      3digit myArray: Array      3digit myArray: Array      3digit myArray: Array

What is wrong?

zavg Over a year ago

@user2758001 To access items it is muxh more conveniebt to use just regurar PHP array $myArray[$i] instead of your suroggate array ${"Array".$i}

zavg Over a year ago

You can not just print arrays with print. You should iterate through its values in loop and print each item separately.

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