If I have an associative array that is structured like
(
1 => 'a',
2 => 'b',
0 => 'c'
)
where all of the keys are numeric, will array_values ALWAYS guarantee that the values occur chronologically, in the new array, based on their previous keys' values, i.e. ['c', 'a', 'b']?
If not, how can I accomplish this instead?
No, array_values() will not reorder the values in any way. It doesn't care about keys.
Its effective implementation is basically this:
function array_values_impl(array $array)
{
$newArray = [];
foreach ($array as $item) {
$newArray[] = $item;
}
return $newArray;
}
If you want to sort the array using the keys, use ksort().
You can accomplish by first sorting the array with keys and getting values by array_values function.
For example
$array = array(
1 => 'a',
2 => 'b',
0 => 'c'
);
ksort($array);
print_r(array_values($array));
Output:
Array
(
[0] => c
[1] => a
[2] => b
)
Related
Here is an example array I want to split:
(1428,217,1428)
How do I split it in 2 array like this?
(1428,1428)
(217)
I have tried following way but it's only return 1428 array.
$counts = array_count_values($array);
$filtered = array_filter($array, function ($value) use ($counts) {
return $counts[$value] > 1;
});
One way to solve this for your example data is to sort the array and use array_shift to get the first element of the array and store that in an array.
$a = [1428,217,1428];
sort($a);
$b = [array_shift($a)];
print_r($a);
print_r($b);
Result
Array
(
[0] => 1428
[1] => 1428
)
Array
(
[0] => 217
)
You can try this.
$array = array(1428,217,1428);
$array1 = array_slice($array, 0, 2);
$array2 = array_slice($array, 2, 3);
print_r($array1);
print_r($array2);
And the output will like this:-
Array
(
[0] => 1428
[1] => 217
)
Array
(
[0] => 1428
)
In your case it will only return 1428 since array_count_values returns an array with values as keys and their frequency as array value therefore $counts will be equal to array('1428' => 2, '217' => 1);
If I understood your question well you should do something like this:
$array1 = [1428, 217, 1428];
$result = [];
foreach($array1 as $value){
$result[$value][] = $value;
}
This will not create an array for each different value but will create a new element for each unique value in $result. The final value of $result will be array('1428' => [1428, 1428], '217' => [217]) . Which can be easily manipulated as if they were 2 different arrays.
Let me know if this works for you, if not I will try to update my answer according to your specification.
How can I get all indexes of an array that have a certain value? array_search() only gives me the first index, but I want all of the indexes. Is there a way to do this
This: array_search( 'a', array( 'a', 'b', 'a' ) ); would return 0 but what really want in this case would be 0 and 2.
array_search() will only return the found key, You should use array_keys with the second parameter as your needle, it will return both indices 0 and 2:
$key = 'a';
$array = array('a', 'b', 'a');
$found = array_keys($array, $key);
print_r($found); // Array ( [0] => 0 [1] => 2 )
I have this array:
$array[] = [
'a' => $a,
'b' => $b,
];
The array contains of let's say 10 entries, $a can be in there with the same value many times and I need only one of those entries for a db insert.
I can't manage to get array_unique working as it throws
array to string conversion
error when trying to use it like
$result = array_unique($array);
I now made a little foreach loop that feels just wrong to do so:
$z = [];
foreach ($array as $x) {
if (#!in_array($x['a'],$z)) {
$z[] = $x['a'];
}
}
and I use $z for the insert thereafter.
Can someone point me in the right direction of how to distinct my array values?
This should work for you:
($result = array_unique($array); this didn't worked, because you have a multidimensional array!)
<?php
//Example data
$array[] = [
'a' => 1,
'b' => 1,
'c' => 1,
'd' => 2,
'e' => 2,
];
$array = array_map("array_unique", $array);
print_r($array);
?>
Output:
Array ( [0] => Array ( [a] => 1 [d] => 2 ) )
Based on your array that is two dimensional, you would need:
$array = array_map('array_unique', $array);
Or if you don't need a two dimensional array, just use:
$array = [
'a' => $a,
'b' => $b,
];
And then: $array = array_unique($array);
One thing not mentioned is that arrays are built in unique, if you can manage the keys for them yourself. Associative arrays can only have the key once. So I like to do is use the primary key or a unique identifier for the key.
You can't have an array with the same keys like this.
array(
'a' => $a
'a' => $b
)
Because the key a is already a unique identifier. If you follow.
I know how to insert it to the end by:
$arr[] = $item;
But how to insert it to the beginning?
Use array_unshift($array, $item);
$arr = array('item2', 'item3', 'item4');
array_unshift($arr , 'item1');
print_r($arr);
will give you
Array
(
[0] => item1
[1] => item2
[2] => item3
[3] => item4
)
In case of an associative array or numbered array where you do not want to change the array keys:
$firstItem = array('foo' => 'bar');
$arr = $firstItem + $arr;
array_merge does not work as it always reindexes the array.
Since PHP7.4 you can use the spread opperator, very similar to JavaScript
$arr = [$item, ...$arr];
https://wiki.php.net/rfc/spread_operator_for_array
A few more examples:
// Add an item before
$arr = [$item, ...$arr];
// Add an item after
$arr = [...$arr, $item];
// Add a few more
$arr = [$item1, $item2, ...$arr, $item3];
// Multiple arrays and and items
$arr = [$item1, ...$arr1, $item2, ...$arr2, $item3];
Note: this is only possible with int keys, not for associative arrays.
Note2: The keys are not kept.
BREAKING Example:
$car = ['brand' => 'Audi', 'model' => 'A8'];
$engine = ['cylinder' => 6, 'displacement' => '3000cc'];
$merged = [...$car, ...$engine];
var_dump($merged);
Will result in:
[ Error ] Cannot unpack array with string keys
For an associative array you can just use merge.
$arr = array('item2', 'item3', 'item4');
$arr = array_merge(array('item1'), $arr)
Insert an item in the beginning of an associative array with string/custom key
<?php
$array = ['keyOne'=>'valueOne', 'keyTwo'=>'valueTwo'];
$array = array_reverse($array);
$array['newKey'] = 'newValue';
$array = array_reverse($array);
RESULT
[
'newKey' => 'newValue',
'keyOne' => 'valueOne',
'keyTwo' => 'valueTwo'
]
There are two solutions:
if you have array with keys that matter to you
$new = ['RLG' => array(1,2,3)];
$array = ['s' => array(2,3), 'l' => [], 'o' => [], 'e' => []];
$arrayWithNewAddedItem = array_merge($new, $array);
if you have an array without any keys.
array_unshift(array, value1);
Use array_unshift() to insert the first element in an array.
Use array_shift() to remove the first element of an array.
Or you can use temporary array and then delete the real one if you want to change it while in cycle:
$array = array(0 => 'a', 1 => 'b', 2 => 'c');
$temp_array = $array[1];
unset($array[1]);
array_unshift($array , $temp_array);
the output will be:
array(0 => 'b', 1 => 'a', 2 => 'c')
and when are doing it while in cycle, you should clean $temp_array after appending item to array.
I have an array which may contain numeric or associative keys, or both:
$x = array('a', 'b', 'c', 'foo' => 'bar', 'd', 'e');
print_r($x);
/*(
[0] => a
[1] => b
[2] => c
[foo] => bar
[3] => d
[4] => e
)*/
I want to be able to remove an item from the array, renumbering the non-associative keys to keep them sequential:
$x = remove($x, "c");
print_r($x);
/* desired output:
(
[0] => a
[1] => b
[foo] => bar
[2] => d
[3] => e
)*/
Finding the right element to remove is no issue, it's the keys that are the problem. unset doesn't renumber the keys, and array_splice works on an offset, rather than a key (ie: take $x from the first example, array_splice($x, 3, 1) would remove the "bar" element rather than the "d" element).
This should re-index the array while preserving string keys:
$x = array_merge($x);
You can fixet with next ELEGANT solution:
For example:
<?php
$array = array (
1 => 'A',
2 => 'B',
3 => 'C'
);
unset($array[2]);
/* $array is now:
Array (
1 => 'A',
3 => 'C'
);
As you can see, the index '2' is missing from the array.
*/
// SOLUTION:
$array = array_values($array);
/* $array is now:
Array (
0 => 'A',
1 => 'C'
);
As you can see, the index begins from zero.
*/
?>
I've come up with this - though I'm not sure if it's the best:
// given: $arr is the array
// $item is the item to remove
$key = array_search($item, $arr); // the key we need to remove
$arrKeys = array_keys($arr);
$keyPos = array_search($key, $arrKeys); // the offset of the item in the array
unset($arr[$key]);
array_splice($arrKeys, $keyPos, 1);
for ($i = $keyPos; $i < count($arrKeys); ++$i) {
if (is_int($arrKeys[$i])) --$arrKeys[$i]; // shift numeric keys back one
}
$arr = array_combine($arrKeys, $arr); // recombine the keys and values.
There's a few things I've left out, just for the sake of brevity. For example, you'd check if the array is associative, and also if the key you're removing is a string or not before using the above code.
Try array_diff() it may not order the new array correctly though
if not the following should work
You will need to iterate over it in the remove function.
function remove($x,$r){
$c = 0;
$a = array();
foreach ($x as $k=>$v){
if ($v != $r) {
if (is_int($k)) {
$a[$c] = $v;
$c++;
}
else {
$a[$k] = $v;
}
}
}
return $a;
}
DC
I don't think there is an elegant solution to this problem, you probably need to loop to the array and reorder the keys by yourself.