Fill missing keys in a (numerically-indexed) array with a default value
<?php
function fill_missing_keys($array, $default = null, $atleast = 0)
{
return $array + array_fill(0, max($atleast, max(array_keys($array))), $default);
}
?>
(PHP 4 >= 4.2.0, PHP 5, PHP 7)
array_fill — 用给定的值填充数组
array_fill() 用 value
参数的值将一个数组填充 num 个条目，键名由
start_index 参数指定的开始。
start_index返回的数组的第一个索引值。
如果 start_index 是负数，
那么返回的数组的第一个索引将会是
start_index ，而后面索引则从0开始。
(参见 例子)。
num插入元素的数量。 必须大于或等于 0。
value用来填充的值。
返回填充后的数组。
如果 num 小于零，将会抛出 E_WARNING。
| 版本 | 说明 |
|---|---|
| 5.6.0 |
num 现在可以是零。
之前
num 必须大于零。
|
Example #1 array_fill() 例子
<?php
$a = array_fill(5, 6, 'banana');
$b = array_fill(-2, 4, 'pear');
print_r($a);
print_r($b);
?>
以上例程会输出：
Array
(
[5] => banana
[6] => banana
[7] => banana
[8] => banana
[9] => banana
[10] => banana
)
Array
(
[-2] => pear
[0] => pear
[1] => pear
[2] => pear
)
参见手册上 数组 一节里关于负数的键的详细解释。
Fill missing keys in a (numerically-indexed) array with a default value
<?php
function fill_missing_keys($array, $default = null, $atleast = 0)
{
return $array + array_fill(0, max($atleast, max(array_keys($array))), $default);
}
?>
If you need negative indices:
<?php
$b = array_fill(-2, 4, 'pear');//this is not what we want
$c = array_fill_keys(range(-2,1),'pear');//these are negative indices
print_r($b);
print_r($c);
?>
Here is result of the code above:
Array
(
[-2] => pear
[0] => pear
[1] => pear
[2] => pear
)
Array
(
[-2] => pear
[-1] => pear
[0] => pear
[1] => pear
)
Using objects with array_fill may cause unexpected results. Consider the following:
<?php
class Foo {
public $bar = "banana";
}
//fill an array with objects
$array = array_fill(0, 2, new Foo());
var_dump($array);
/*
array(2) {
[0]=>
object(Foo)#1 (1) {
["bar"]=>
string(6) "banana"
}
[1]=>
object(Foo)#1 (1) {
["bar"]=>
string(6) "banana"
}
} */
//now we change the attribute of the object stored in index 0
//this actually changes the attribute for EACH object in the ENTIRE array
$array[0]->bar = "apple";
var_dump($array);
/*
array(2) {
[0]=>
object(Foo)#1 (1) {
["bar"]=>
string(5) "apple"
}
[1]=>
object(Foo)#1 (1) {
["bar"]=>
string(5) "apple"
}
}
*/
?>
Objects are filled in the array BY REFERENCE. They are not copied for each element in the array.
I made this function named "array_getMax" that returns te maximum value and index, from array:
<?php
//using array_search_all by helenadeus at gmail dot com
function array_search_all($needle, $haystack)
{#array_search_match($needle, $haystack) returns all the keys of the values that match $needle in $haystack
foreach ($haystack as $k=>$v) {
if($haystack[$k]==$needle){
$array[] = $k;
}
}
return ($array);
}
function array_getMax($array){
$conteo=array_count_values($array);
if( count($conteo)==1 ){//returns full array when all values are the same.
return $array;
}
arsort($array);
//$antValue=null;
$maxValue=null;
$keyValue=null;
foreach($array as $key=>$value){
if($maxValue==null){
$maxValue=$value;
$keyValue=$key;
break;
}
}
$resultSearch=array_search_all($maxValue, $array);
return array_fill_keys($resultSearch, $maxValue);
}
//example
$arreglo=array('e1'=>99,'e2'=>'99','e3'=>1,'e4'=>1,'e5'=>98);
var_dump(array_getMax($arreglo));
//output
/*
array(2) {
["e1"]=>
int(99)
["e2"]=>
int(99)
}
*/
?>
I hope some one find this usefull
This is what I recently did to quickly create a two dimensional array (10x10), initialized to 0:
<?php
$a = array_fill(0, 10, array_fill(0, 10, 0));
?>
This should work for as many dimensions as you want, each time passing to array_fill() (as the 3rd argument) another array_fill() function.
array_fill() cannot be used to setup only missing keys in an array. This may be necessary for example before using implode() on a sparse filled array.
The solution is to use this function:
<?php
function array_setkeys(&$array, $fill = NULL) {
$indexmax = -1;
for (end($array); $key = key($array); prev($array)) {
if ($key > $indexmax)
$indexmax = $key;
}
for ($i = 0; $i <= $indexmax; $i++) {
if (!isset($array[$i]))
$array[$i] = $fill;
}
ksort($array);
}
?>
This is usefull in some situations where you don't know which key index was filled and you want to preserve the association between a positioned field in an imploded array and the key index when exploding it.