Lets say i have an array in PHP
$test['michael_unique_id'] = 3;
$test['john_unique_id'] = 8;
$test['mary_unique_id'] = 10;
.
.
.
.
$test['jimmy_unique_id'] = 4;
(the values (3,8,10.........4) are unique)
Lets say i want to search for the unique id 10, and get the order of the matching element in the array. In this example, the third element has the value 10, so i should get the number 3.
I can do it by scanning with a for loop looking for the value i'm searching and then get the $i value when i have a match, but i wonder if there is any built-in function (or a better method) that implements this.
You can get all of the array's values as an array with array_values() and then use array_search() to get the position (offset) of that value in the array.
$uniq_id = 10;
$all_vals = array_values($test); // => array(3, 8, 10, ... )
echo array_search( $uniq_id, $all_vals ); // => 2
Because PHP array indices are zero-based, you'll get 0 for the first item, 1 for the second item, etc. If you want the first item to be "1," then just add one. All together now:
$uniq_id = 10;
echo array_search( $uniq_id, array_values( $test ) ) + 1; // => 3
It's not clear to me, however, that this is necessarily as performant as just doing a foreach:
$uniq_id = 10;
$idx = 1;
foreach($test as $val) {
if($val == $uniq_id) {
break;
}
$idx++;
}
echo $idx; // => 3
Well, array_search will give you the key, but in your case, you want the index of that key, so I believe a loop is your best bet. Is there a good reason why you need the index? It doesn't seem very useful to me.
Related
From a given array (eg: $_SERVER), I need to get the first and last key and value. I was trying use array_shift to get first value and key but what I get is value.
Here is the $_SERVER array:
print_r($_SERVER, true))
And I tried with:
echo array_shift($_SERVER);
With PHP >= 7.3 you can get it fast, without modification of the array and without creating array copies:
$first_key = array_key_first($_SERVER);
$first_value = $_SERVER[$first_key];
$last_key = array_key_last($_SERVER);
$last_value = $_SERVER[$last_key];
See array_key_first and array_key_last.
It's not clear if you want the value, or the key. This is about as efficient as it gets, if memory usage is important.
If you want the key, use array_keys. If you want the value, just refer to it with the key you got from array_keys.
$count = count($_SERVER);
if ($count > 0) {
$keys = array_keys($_SERVER);
$firstKey = $keys[0];
$lastKey = $keys[$count - 1];
$firstValue = $array[$firstKey];
$lastValue = $array[$lastKey];
}
You can't use $count - 1 or 0 to get the first or last value in keyed arrays.
You can do a foreach loop, and break out after the first one:
foreach ( $_SERVER as $key => $value ) {
//Do stuff with $key and $value
break;
}
Plenty of other methods here. You can pick and choose your favorite flavor there.
Separate out keys and values in separate arrays, and extract first and last from them:
// Get all the keys in the array
$all_keys = array_keys($_SERVER);
// Get all the values in the array
$all_values = array_values($_SERVER);
// first key and value
$first_key = array_shift($all_keys);
$first_value = array_shift($all_values);
// last key and value (we dont care about the pointer for the temp created arrays)
$last_key = end($all_keys);
$last_value = end($all_values);
/* you can use reset function after end function call
if you worry about the pointer */
What about this:
$server = $_SERVER;
echo array_shift(array_values($server));
echo array_shift(array_keys($server));
reversed:
$reversed = array_reverse($server);
echo array_shift(array_values($reversed));
echo array_shift(array_keys($reversed));
I think array_slice() will do the trick for you.
<?php
$a = array_slice($_SERVER, 0, 1);
$b = array_slice($_SERVER, -1, 1, true);
//print_r($_SERVER);
print_r($a);
print_r($b);
?>
OUTPUT
Array ( [TERM] => xterm )
Array ( [argc] => 1 )
DEMO: https://3v4l.org/GhoFm
Example array:
$items = array(
array('sort': 1, 'name': 'name'),
array('sort': 3, 'name': 'name'),
array('sort': null, 'name': 'name')
);
I need to know if all child arrays have the sort key. If not, I'd manually create the sort via a for loop (and over-write the sort value for the ones that have it).
I'm already running a for loop, and I was thinking of adding another key such as manual_sort which I would equal to index + 1, and after the loop, if at least 1 array didn't have the sort key or if it's null), I'd use the manual_sort instead of the sort key (for example when looping the elements via the front-end or whatever usage the data has).
Also thought about doing a second loop to know whether or not sort should be overwritten.
These seems like dirty solutions though, any ideas?
My current code looks something like:
$db_sorted_items = true;
for ($i=0; $i < count($items); $i++) {
$items[$i]['name'] = ucfirst($items[$i]['name']);
if (empty($items[$i]['sort']) {
$db_sorted_items = false;
}
$items[$i]['number'] = $i + 1; // $i+1 because sort number starts at 1.
}
// err, gotta use `$items[$i]['number']` (or `sort` had all arrays had a positive `sort` key)
// use array_column to get array for key 'sort'
// then use array_filter to remove null values
// then compare count
if(count($array) == count(array_filter(array_column($array,'sort')))){
echo 'All have valid sort key';
}else{
echo 'No, few are missing';
}
In case if you want to have strict check, to make sure value corresponding to key sort is numeric then you may use below one, using is_numeric
if(count($array)==count(array_filter(array_column($array,'sort'),'is_numeric'))){
}
Your code looks good to me. I'd change it so it refreshes all sort attributes if it finds one object that doesn't have it, like this:
$db_sorted_items = true;
for ($i=0; $i < count($items); $i++) {
$items[$i]['name'] = ucfirst($items[$i]['name']);
if ($db_sorted_items && empty($items[$i]['sort']) {
$db_sorted_items = false;
$i = -1; // Re-start for (the for will add 1 at the end)
}else{
$items[$i]['sort'] = $i + 1; // $i+1 because sort number starts at 1.
}
}
Suppose i have an array
$x= ('A'=>31, 'B'=>12, 'C'=>13, 'D'=>25, 'E'=>18, 'F'=>10);
I need to generate an array somewhat like this
$newx = (0 => array('A'=>31 , 'B' =>1) , 1 => array('B'=>11 , 'C' =>13 , 'D'=>8) , 2 =>array('D'=>17 , 'E'=>15) , 3=>array('E'=>3,'F'=>10);
Now in this case each value of $newx has to be = 32 and this is how it will work $x[A] = 31 , $x[B] = 12 so first of all we have to make the sum quantity to be 32 keeping the index same for the new array i.e
array(0=>array('A'=>31,'B'=>1) , 1=>array('B'=>11) )
the process should continue for each value of $x.
while I'm pretty sure this is a homework assignment and well, you really should provide code of your own, at least try to, I found the thing amusing so I went ahead and gave it a try. I guess I'll be downvoted for his and I probably do deserve it, but here goes anyway.
What you need to do is:
loop through your array,
determine the elements that give you 32 and then store that result in the final array.
subtract the value of the last element from your result from the corresponding element of your working array
shrink your array next by deleting the first elements until the very first element of the array you're still working with equals the last element your last result returned.
if your last result < 32, quit.
With this in mind, please try to find a solution yourself first and don't just copy-paste the code? :)
<?php
$x = array('A'=>31, 'B'=>12, 'C'=>13, 'D'=>25, 'E'=>18, 'F'=>10);
$result = array();
function calc($toWalk){
// walk through the array until we have gathered enough for 32, return result as an array
$result = array();
foreach($toWalk as $key => $value){
$count = array_sum($result);
if($count >= 32){
// if we have more than 32, subtract the overage from the last array element
$last = array_pop(array_keys($result));
$result[$last] -= ($count - 32);
return $result;
}
$result[$key] = $value;
}
return $result;
}
// logic match first element
$last = 'A';
// loop for as long as we have an array
while(count($x) > 0){
/*
we make sure that the first element matches the last element of the previously found array
so that if the last one went from A -> C we start at C and not at B
*/
$keys = array_keys($x);
if($last == $keys[0]){
// get the sub-array
$partial = calc($x);
// determine the last key used, it's our new starting point
$last = array_pop(array_keys($partial));
$result[] = $partial;
//subtract last (partial) value used from corresponding key in working array
$x[$last] -= $partial[$last];
if(array_sum($partial) < 32) break;
}
/*
reduce the array in size by 1, dropping the first element
should our resulting first element not match the previously returned
$last element then the logic will jump to this place again and
just cut off another element
*/
$x = array_slice($x , 1 );
}
print_r($result);
This question already has answers here:
How do I select 10 random things from a list in PHP?
(5 answers)
Closed 8 months ago.
From an array
$my_array = array('a','b','c','d','e');
I want to get two DIFFERENT random elements.
With the following code:
for ($i=0; $i<2; $i++) {
$random = array_rand($my_array); # one random array element number
$get_it = $my_array[$random]; # get the letter from the array
echo $get_it;
}
it is possible to get two times the same letter. I need to prevent this. I want to get always two different array elements. Can somebody tell me how to do that?
Thanks
array_rand() can take two parameters, the array and the number of (different) elements you want to pick.
mixed array_rand ( array $input [, int $num_req = 1 ] )
$my_array = array('a','b','c','d','e');
foreach( array_rand($my_array, 2) as $key ) {
echo $my_array[$key];
}
What about this?
$random = $my_array; // make a copy of the array
shuffle($random); // randomize the order
echo array_pop($random); // take the last element and remove it
echo array_pop($random); // s.a.
You could always remove the element that you selected the first time round, then you wouldn't pick it again. If you don't want to modify the array create a copy.
for ($i=0; $i<2; $i++) {
$random = array_rand($my_array); # one random array element number
$get_it = $my_array[$random]; # get the letter from the array
echo $get_it;
unset($my_array[$random]);
}
You can shuffle and then pick a slice of two. Use another variable if you want to keep the original array intact.
$your_array=[1,2,3,4,5,6,7];
shuffle($your_array); // randomize the order
$your_array = array_slice($your_array, 0, 2); //pick 2
foreach (array_intersect_key($arr, array_flip(array_rand($arr, 2))) as $k => $v) {
echo "$k:$v\n";
}
//or
list($a, $b) = array_values(array_intersect_key($arr, array_flip(array_rand($arr, 2))));
here's a simple function I use for pulling multiple random elements from an array.
function get_random_elements( $array, $limit=0 ){
shuffle($array);
if ( $limit > 0 ) {
$array = array_splice($array, 0, $limit);
}
return $array;
}
Here's how I did it. Hopefully this helps anyone confused.
$originalArray = array( 'first', 'second', 'third', 'fourth' );
$newArray= $originalArray;
shuffle( $newArray);
for ($i=0; $i<2; $i++) {
echo $newArray[$i];
}
Get the first random, then use a do..while loop to get the second:
$random1 = array_rand($my_array);
do {
$random2 = array_rand($my_array);
} while($random1 == $random2);
This will keep looping until random2 is not the same as random1
I need to merge several arrays into a single array. The best way to describe what I'm looking for is "interleaving" the arrays into a single array.
For example take item one from array #1 and append to the final array. Get item one from array #2 and append to the final array. Get item two from array #1 and append...etc.
The final array would look something like this:
array#1.element#1
array#2.element#1
.
.
.
The "kicker" is that the individual arrays can be of various lengths.
Is there a better data structure to use?
for example,
function array_zip_merge() {
$output = array();
// The loop incrementer takes each array out of the loop as it gets emptied by array_shift().
for ($args = func_get_args(); count($args); $args = array_filter($args)) {
// &$arg allows array_shift() to change the original.
foreach ($args as &$arg) {
$output[] = array_shift($arg);
}
}
return $output;
}
// test
$a = range(1, 10);
$b = range('a', 'f');
$c = range('A', 'B');
echo implode('', array_zip_merge($a, $b, $c)); // prints 1aA2bB3c4d5e6f78910
If the arrays only have numeric keys, here's a simple solution:
$longest = max( count($arr1), count($arr2) );
$final = array();
for ( $i = 0; $i < $longest; $i++ )
{
if ( isset( $arr1[$i] ) )
$final[] = $arr1[$i];
if ( isset( $arr2[$i] ) )
$final[] = $arr2[$i];
}
If you have named keys you can use the array_keys function for each array and loop over the array of keys instead.
If you want more than two arrays (or variable number of arrays) then you might be able to use a nested loop (though I think you'd need to have $arr[0] and $arr[1] as the individual arrays).
I would just use array_merge(), but that obviously depends on what exactly you do.
This would append those arrays to each other, while elements would only be replaced when they have the same non-numerical key. And that might not be a problem for you, or it might be possible to be solved because of attribute order, since the contents of the first arrays' elements will be overwritten by the later ones.
If you have n arrays, you could use a SortedList, and use arrayIndex * n + arrayNumber as a sort index.