I have an array like
$myArray =array
(
"0"=>array("dogs",98),
"1"=>array("cats",56),
"2"=>array("buffaloes",78)
)
How can I get a key by providing a value?
e.g. if i search for "buffaloes" array_search may return "2".
Thanks
$myArray =array
(
"0"=>array("dogs",98),
"1"=>array("cats",56),
"2"=>array("buffaloes",78)
);
function findInArray($term, $array) {
foreach($array as $key => $val) {
if(in_array($term, $val, true)) {
return $key;
}
}
}
echo findInArray('buffaloes', $myArray); // 2
echo findInArray(78, $myArray); // 2
function asearch($key, $myArray) {
for ($i = 0; $i < sizeof($myArray); $i++) {
if ($myArray[$i][0] == $key) {
return $i;
}
}
return -1; # no match
}
Though, you'd probably want to restructure your array to:
$myarray = array(
'dogs' => 98,
'cats' => 56,
'buffaloes' => 78
);
And just do:
$myArray['buffaloes']; # 78
The only way you can do it is to iterate over every item and preform a Linear Search
$i = -1;
foreach ($myArray as $key => $item){
if ( $item[0] == 'buffaloes' ){
$i = $key;
break;
}
}
//$i now holds the key, or -1 if it doesn't exist
As you can see, it is really really inefficient, as if your array has 20,000 items and 'buffaloes' is the last item, you have to make 20,000 comparisons.
In other words, you need to redesign your data structures so that you can look something up using the key, for example a better way may be to rearrange your array so that you have the string you are searching for as the key, for example:
$myArray['buffaloes'] = 76;
Which is much much faster, as it uses a better data structure so that it only has to at most n log n comparisons (where n is the number of items in the array). This is because an array is in fact an ordered map.
Another option, if you know the exact value of the value you are searching for is to use array_search
I never heard of built in function. If you want something more general then above solutions you shold write your own function and use recursion. maybe array_walk_recursive would be helpful
You can loop over each elements of the array, testing if the first element of each entry is equal to "buffaloes".
For instance :
foreach ($myArray as $key => $value) {
if ($value[0] == "buffaloes") {
echo "The key is : $key";
}
}
Will get you :
The key is : 2
Another idea (more funny ?), if you want to whole entry, might be to work with array_filter and a callback function that returns true for the "bufalloes" entry :
function my_func($val) {
return $val[0] == "buffaloes";
}
$element = array_filter($myArray, 'my_func');
var_dump($element);
Will get you :
array
2 =>
array
0 => string 'buffaloes' (length=9)
1 => int 78
And
var_dump(key($element));
Gves you the 2 you wanted.
Related
I am trying to sort it in a repeating, sequential pattern of numerical order with the largest sets first.
Sample array:
$array = [1,1,1,2,3,2,3,4,5,4,4,4,5,1,2,2,3];
In the above array, I have the highest value of 5 which appears twice so the first two sets would 1,2,3,4,5 then it would revert to the second, highest value set etc.
Desired result:
[1,2,3,4,5,1,2,3,4,5,1,2,3,4,1,2,4]
I am pretty sure I can split the array into chunks of the integer values then cherrypick an item from each subarray sequentially until there are no remaining items, but I just feel that this is going to be poor for performance and I don't want to miss a simple trick that PHP can already handle.
Here's my attempt at a very manual loop using process, the idea is to simply sort the numbers into containers for array_unshifting. I'm sure this is terrible and I'd love someone to do this in five lines or less :)
$array = array(1,1,1,2,3,2,3,4,5,4,4,4,5,1,2,2,3);
sort($array);
// Build the container array
$numbers = array_fill_keys(array_unique($array),array());
// Assignment
foreach( $array as $number )
{
$numbers[ $number ][] = $number;
}
// Worker Loop
$output = array();
while( empty( $numbers ) === false )
{
foreach( $numbers as $outer => $inner )
{
$output[] = array_shift( $numbers[ $outer ] );
if( empty( $numbers[ $outer ] ) )
{
unset( $numbers[ $outer ] );
}
}
}
var_dump( $output );
I think I'd look at this not as a sorting problem, but alternating values from multiple lists, so rather than coming up with sets of distinct numbers I'd make sets of the same number.
Since there's no difference between one 1 and another, all you actually need is to count the number of times each appears. It turns out PHP can do this for you with aaray_count_values.
$sets = array_count_values ($input);
Then we can make sure the sets are in order by sorting by key:
ksort($sets);
Now, we iterate round our sets, counting down how many times we've output each number. Once we've "drained" a set, we remove it from the list, and once we have no sets left, we're all done:
$output = [];
while ( count($sets) > 0 ) {
foreach ( $sets as $number => $count ) {
$output[] = $number;
if ( --$sets[$number] == 0 ) {
unset($sets[$number]);
}
}
}
This algorithm could be adapted for cases where the values are actually distinct but can be put into sets, by having the value of each set be a list rather than a count. Instead of -- you'd use array_shift, and then check if the length of the set was zero.
You can use only linear logic to sort using php functions. Here is optimized way to fill data structures. It can be used for streams, generators or anything else you can iterate and compare.
$array = array(1,1,1,2,3,2,3,4,5,4,4,4,5,1,2,2,3);
sort($array);
$chunks = [];
$index = [];
foreach($array as $i){
if(!isset($index[$i])){
$index[$i]=0;
}
if(!isset($chunks[$index[$i]])){
$chunks[$index[$i]]=[$i];
} else {
$chunks[$index[$i]][] = $i;
}
$index[$i]++;
}
$result = call_user_func_array('array_merge', $chunks);
print_r($result);
<?php
$array = array(1,1,1,2,3,2,3,4,5,4,4,4,5,1,2,2,3);
sort($array);
while($array) {
$n = 0;
foreach($array as $k => $v) {
if($v>$n) {
$result[] = $n = $v;
unset($array[$k]);
}
}
}
echo implode(',', $result);
Output:
1,2,3,4,5,1,2,3,4,5,1,2,3,4,1,2,4
New, more elegant, more performant, more concise answer:
Create a sorting array where each number gets its own independent counter to increment. Then use array_multisort() to sort by this grouping array, then sort by values ascending.
Code: (Demo)
$encounters = [];
foreach ($array as $v) {
$encounters[] = $e[$v] = ($e[$v] ?? 0) + 1;
}
array_multisort($encounters, $array);
var_export($array);
Or with a functional style with no global variable declarations: (Demo)
array_multisort(
array_map(
function($v) {
static $e;
return $e[$v] = ($e[$v] ?? 0) + 1;
},
$array
),
$array
);
var_export($array);
Old answer:
My advice is functionally identical to #El''s snippet, but is implemented in a more concise/modern/attractive fashion.
After ensuring that the input array is sorted, make only one pass over the array and push each re-encountered value into its next row of values. The $counter variable indicates which row (in $grouped) the current value should be pushed into. When finished looping and grouping, $grouped will have unique values in each row. The final step is to merge/flatten the rows (preserving their order).
Code: (Demo)
$grouped = [];
$counter = [];
sort($array);
foreach ($array as $v) {
$counter[$v] = ($counter[$v] ?? -1) + 1;
$grouped[$counter[$v]][] = $v;
}
var_export(array_merge(...$grouped));
Let's say I have a multidimensional array like this:
[
["Thing1", "OtherThing1"],
["Thing1", "OtherThing2"],
["Thing2", "OtherThing3"]
]
How would I be able to count how many times the value "Thing1" occurs in the multidimensional array?
you can use array_search for more information see this http://www.php.net/manual/en/function.array-search.php
this code is sample of this that is in php document sample
<?php
function recursiveArraySearchAll($haystack, $needle, $index = null)
{
$aIt = new RecursiveArrayIterator($haystack);
$it = new RecursiveIteratorIterator($aIt);
$resultkeys;
while($it->valid()) {
if (((isset($index) AND ($it->key() == $index)) OR (!isset($index))) AND (strpos($it->current(), $needle)!==false)) { //$it->current() == $needle
$resultkeys[]=$aIt->key(); //return $aIt->key();
}
$it->next();
}
return $resultkeys; // return all finding in an array
} ;
?>
If needle is found in haystack more than once, the first matching key is returned. To return the keys for all matching values, use array_keys() with the optional search_value parameter instead.
http://www.php.net/manual/en/function.array-keys.php
Try this :
$arr =array(
array("Thing1","OtherThing1"),
array("Thing1","OtherThing2"),
array("Thing2","OtherThing3")
);
echo "<pre>";
$res = array_count_values(call_user_func_array('array_merge', $arr));
echo $res['Thing1'];
Output :
Array
(
[Thing1] => 2
[OtherThing1] => 1
[OtherThing2] => 1
[Thing2] => 1
[OtherThing3] => 1
)
It gives the occurrence of each value. ie : Thing1 occurs 2 times.
EDIT : As per OP's comment : "Which array do you mean resulting array?" - The input array. So for example this would be the input array: array(array(1,1),array(2,1),array(3,2)) , I only want it to count the first values (1,2,3) not the second values (1,1,2) – gdscei 7 mins ago
$arr =array(
array("Thing1","OtherThing1"),
array("Thing1","OtherThing2"),
array("Thing2","OtherThing3")
);
$res = array_count_values(array_map(function($a){return $a[0];}, $arr));
echo $res['Thing1'];
function showCount($arr, $needle, $count=0)
{
// Check if $arr is array. Thx to Waygood
if(!is_array($arr)) return false;
foreach($arr as $k=>$v)
{
// if item is array do recursion
if(is_array($v))
{
$count = showCount($v, $needle, $count);
}
elseif($v == $needle){
$count++;
}
}
return $count;
}
Using in_array can help:
$cont = 0;
//for each array inside the multidimensional one
foreach($multidimensional as $m){
if(in_array('Thing1', $m)){
$cont++;
}
}
echo $cont;
For more info: http://php.net/manual/en/function.in-array.php
try this
$arr =array(
array("Thing1","OtherThing1"),
array("Thing1","OtherThing2"),
array("Thing2","OtherThing3")
);
$abc=array_count_values(call_user_func_array('array_merge', $arr));
echo $abc[Thing1];
$count = 0;
foreach($array as $key => $value)
{
if(in_array("Thing1", $value)) $count++;
}
If you prefer code brevity zero global scope pollution, you can count every value and access the one count that you do want:
echo array_count_values(array_merge(...$array))['Thing1'] ?? 0;
If you don't want to bother counting values where the count will never be needed, then you can visit leafnodes with array_walk_recursive() and +1 everytime the target value is encountered.
$thing1Count = 0;
array_walk_recursive($array, function($v) use(&$thing1Count) { $thing1Count += ($v === 'Thing1'); });
echo $thing1Count;
Both snippets return 2. Here's a Demo.
This is what I have tried:
foreach ($multiarr as $arr) {
foreach ($arr as $key=>$val) {
if (next($arr) === false) {
//work on last key
} else {
//work
}
}
}
After taking another look, I thinknext is being used wrong here, but I am not sure what to do about it.
Is it possible to see if I'm on the last iteration of this array?
$lastkey = array_pop(array_keys($arr));
$lastvalue = $arr[$lastkey];
If you want to use it in a loop, just compare $lastkey to $key
You will need to keep a count of iterations and check it against the length of the array you are iterating over. The default Iterator implementation in PHP does not allow you to check whether the next element is valid -- next has a void return and the api only exposes a method to check whether the current position is valid. See here http://php.net/manual/en/class.iterator.php. To implement the functionality you are thinking about you would have to implement your own iterator with a peek() or nextIsValid() method.
Try this:
foreach ($multiarr as $arr) {
$cnt=count($arr);
foreach ($arr as $key=>$val) {
if (!--$cnt) {
//work on last key
} else {
//work
}
}
}
See below url i think it help full to you:-
How to get last key in an array?
How to get last key in an array?
Update:
<?php
$array = array(
array(
'first' => 123,
'second' => 456,
'last' => 789),
array(
'first' => 123,
'second' => 456,
'last_one' => 789),
);
foreach ($array as $arr) {
end($arr); // move the internal pointer to the end of the array
$key = key($arr); // fetches the key of the element pointed to by the internal pointer
var_dump($key);
}
output:
string(4) "last" string(4) "last_one"
This function (in theory, I haven't tested it) will return the last and deepest key in a multidemnsional associative array. Give I a run, I think you'll like it.
function recursiveEndOfArrayFinder($multiarr){
$listofkeys = array_keys($multiarr);
$lastkey = end($listofkeys);
if(is_array($multiarr[$lastkey])){
recursiveEndOfArrayFinder($multiarr[$lastkey]);
}else{
return $lastkey;
}
}
So far, if I have to loop through a multidimensional array, I use a foreach loop for each dimension.
e.g for two dimensions
foreach($array as $key=>$value)
{
foreach($value as $k2=>$v2)
{
echo
}
}
What do I do when I don't know the depth of the array? ie the depth is variable.
The only thing I can think of is to code a whole stack of loops and to break the loop if the next value is not an array.This seems a little silly.
Is there a better way?
Yes, you can use recursion. Here's an example where you output all the elements in an array:
function printAll($a) {
if (!is_array($a)) {
echo $a, ' ';
return;
}
foreach($a as $v) {
printAll($v);
}
}
$array = array('hello',
array('world',
'!',
array('whats'),
'up'),
array('?'));
printAll($array);
What you should always remember when doing recursion is that you need a base case where you won't go any deeper.
I like to check for the base case before continuing the function. That's a common idiom, but is not strictly necessary. You can just as well check in the foreach loop if you should output or do a recursive call, but I often find the code to be harder to maintain that way.
The "distance" between your current input and the base case is called a variant and is an integer. The variant should be strictly decreasing in every recursive call. The variant in the previous example is the depth of $a. If you don't think about the variant you risk ending up with infinite recursions and eventually the script will die due to a stack overflow. It's not uncommon to document exactly what the variant is in a comment before recursive functions.
You can do the below function for loop-through-a-multidimensional-array-without-knowing-its-depth
// recursive function loop through the dimensional array
function loop($array){
//loop each row of array
foreach($array as $key => $value)
{
//if the value is array, it will do the recursive
if(is_array($value) ) $array[$key] = loop($array[$key]);
if(!is_array($value))
{
// you can do your algorithm here
// example:
$array[$key] = (string) $value; // cast value to string data type
}
}
return $array;
}
by using above function, it will go through each of the multi dimensional array, below is the sample array you could pass to loop function :
//array sample to pass to loop() function
$data = [
'invoice' => [
'bill_information' => [
'price' => 200.00,
'quantity' => 5
],
'price_per_quantity' => 50.00
],
'user_id' => 20
];
// then you can pass it like this :
$result = loop($data);
var_dump($result);
//it will convert all the value to string for this example purpose
You can use recursion for this problem:
Here is one example
$array = array(1 => array(1 => "a", 2 => array(1 => "b", 2 => "c", 3 => array(1 => "final value"))));
//print_r($array);
printAllValues($array);
function printAllValues($arr) {
if(!is_array($arr)) {
echo '<br />' . $arr;
return;
}
foreach($arr as $k => $v) {
printAllValues($v);
}
}
It will use recursion to loop through array
It will print like
a
b
c
final value
Simple function inside array_walk_recursive to show the level of nesting and the keys and values:
array_walk_recursive($array, function($v, $k) {
static $l = 0;
echo "Level " . $l++ . ": $k => $v\n";
});
Another one showing use with a reference to get a result:
array_walk_recursive($array, function($v) use(&$result) {
$result[] = $v;
});
Based on previous recursion examples, here is a function that keeps an array of the path of keys a value is under, in case you need to know how you got there:
function recurse($a,$keys=array())
{
if (!is_array($a))
{
echo implode("-", $keys)." => $a <br>";
return;
}
foreach($a as $k=>$v)
{
$newkeys = array_merge($keys,array($k));
recurse($v,$newkeys);
}
}
recurse($array);
I want to replace all array values with 0 except work and home.
Input:
$array = ['work', 'homework', 'home', 'sky', 'door']
My coding attempt:
$a = str_replace("work", "0", $array);
Expected output:
['work', 0, 'home', 0, 0]
Also my input data is coming from a user submission and the amount of array elements may be very large.
A bit more elegant and shorter solution.
$aArray = array('work','home','sky','door');
foreach($aArray as &$sValue)
{
if ( $sValue!='work' && $sValue!='home' ) $sValue=0;
}
The & operator is a pointer to the particular original string in the array. (instead of a copy of that string)
You can that way assign a new value to the string in the array. The only thing you may not do is anything that may disturb the order in the array, like unset() or key manipulation.
The resulting array of the example above will be
$aArray = array('work','home', 0, 0)
A loop will perform a series of actions many times. So, for each element in your array, you would check if it is equal to the one you want to change and if it is, change it. Also be sure to put quote marks around your strings
//Setup the array of string
$asting = array('work','home','sky','door')
/**
Loop over the array of strings with a counter $i,
Continue doing this until it hits the last element in the array
which will be at count($asting)
*/
for($i = 0; $i < count($asting);$i++){
//Check if the value at the 'ith' element in the array is the one you want to change
//if it is, set the ith element to 0
if ($asting[$i] == 'work' || $asting[$i] == 'home')
$asting[$i] = 0;
}
Here is some suggested reading:
http://www.php.net/manual/en/language.types.array.php
http://www.php.net/manual/en/language.control-structures.php
But if you are struggling on stuff such as looping, you may want to read some introductory programming material. Which should help you really understand what's going on.
A bit other and much quicker way, but true, need a loop:
//Setup the array of string
$asting = array('bar', 'market', 'work', 'home', 'sky', 'door');
//Setup the array of replacings
$replace = array('home', 'work');
//Loop them through str_replace() replacing with 0 or any other value...
foreach ($replace as $val) $asting = str_replace($val, 0, $asting);
//See what results brings:
print_r ($asting);
Will output:
Array
(
[0] => bar
[1] => market
[2] => 0
[3] => 0
[4] => sky
[5] => door
)
An alternative using array_map:
$original = array('work','home','sky','door');
$mapped = array_map(function($i){
$exclude = array('work','home');
return in_array($i, $exclude) ? 0 : $i;
}, $original);
you may try array_walk function:
function zeros(&$value)
{
if ($value != 'home' && $value != 'work'){$value = 0;}
}
$asting = array('work','home','sky','door','march');
array_walk($asting, 'zeros');
print_r($asting);
You can also give array as a parameter 1 and 2 on str_replace...
Just a small point to the for loop. Many dont realize the second comparing task is done every new iteration. So if it was a case of big array or calculation you could optimize loop a bit by doing:
for ($i = 0, $c = count($asting); $i < $c; $i++) {...}
You may also want to see http://php.net/manual/en/function.array-replace.php for original problem unless the code really is final :)
Try This
$your_array = array('work','home','sky','door');
$rep = array('home', 'work');
foreach($rep as $key=>$val){
$key = array_search($val, $your_array);
$your_array[$key] = 0;
}
print_r($your_array);
There are a few techniques on this page that make zero iterated function calls -- which is good performance-wise. For best maintainability, I recommend separating your list of targeted string as a lookup array. By modifying the original array values by reference, you can swiftly replace whole strings and null coalesce non-targeted values to 0.
Code: (Demo)
$array = ['work', 'homework', 'home', 'sky', 'door'];
$keep = ['work', 'home'];
$lookup = array_combine($keep, $keep);
foreach ($array as &$v) {
$v = $lookup[$v] ?? 0;
}
var_export($array);
Output:
array (
0 => 'work',
1 => 0,
2 => 'home',
3 => 0,
4 => 0,
)
You can very easily, cleanly extend your list of targeted strings by merely extending $keep.
If you don't want a classic loop, you can use the same technique without modifying the original array. (Demo)
var_export(
array_map(fn($v) => $lookup[$v] ?? 0, $array)
);
this my final code
//Setup the array of string
$asting = array('work','home','sky','door','march');
/**
Loop over the array of strings with a counter $i,
Continue doing this until it hits the last element in the array
which will be at count($asting)
*/
for($i = 0; $i < count($asting); $i++) {
//Check if the value at the 'ith' element in the array is the one you want to change
//if it is, set the ith element to 0
if ($asting[$i] == 'work') {
$asting[$i] = 20;
} elseif($asting[$i] == 'home'){
$asting[$i] = 30;
}else{
$asting[$i] = 0;
}
echo $asting[$i]."<br><br>";
$total += $asting[$i];
}
echo $total;