Currently i have an array $newArr with some elements as shown in picture below. How do I know the last digit of the array index (highlighted in yellow)?
This is important because, if later I wanted to insert a new record into this $newArr array, I could just
$newArr[$the_variable_that_holds_the_last_digit + 1] = ['foo', 'bar'];
otherwise the whole array overwrite if
$newArr = ['foo', 'bar'];
I think you are looking for end pointer
$array = array(
'a' => 1,
'b' => 2,
'c' => 3,
);
end($array); // it will point to last key
$key = key($array); // get the last key using `key`
Assuming you have the numerically indexed array, the last index on your array is :
$last_index = count($newArr) -1;
if However your keys are not sequential, you can do this:
end($newArr);
$last_key = key($newArr);
I think you can try this
$array = end($newArr);
$last_index = key($array);//Its display last key of array
For more details, please follow this link.
If the only reason is to not overwrite the values you can use [] which means add new value.
$arr = [1,2,3,4];
var_dump($arr);
// incorrect way:
$arr = [1,2];
var_dump($arr);
//correct way
$arr = [1,2,3,4];
$arr[] = [1,2];
var_dump($arr);
See here for output: https://3v4l.org/ZTg28
The "correct way" will in the example above input a new array in the array.
If you want to add only the values you need to insert them one at the time.
$arr[] = 1;
$arr[] = 2;
Someone could be so nice to tell me how to do the following with 2 ore more arrays in PHP:
array 1 (a,b,c,d)
array 2 (1,2,3,4)
I would like to merge the two arrays in an unique array with the merged values:
Result: unique array (a-1,b-2,c-3,d-4).
Is there any function that does so? I could not find anything in the forum either on the web.
Thanks for all your answers but I guess that my arrays are a bit more structured because I need the final result for a dropdown field.
Now I have these 2 arrays:
$array1[] = array( 'text' => $hospital['value'], 'value' => $hospital['value'] );
$array2[] = array( 'text' => $company['value'], 'value' => $company['value'] );
I want to have a final array that contains: Hospital1 - Company1, Hospital2 - Company2, Hospital3 - Company3, etc..
Thanks
You can use array_map:
$result = array_map(function ($item1, $item2) {
return "$item1-$item2";
}, $array1, $array2);
Here is working demo.
You would have to create a loop to do this manually. it might look something like the following:
$a = array(a,b,c,d);
$b = array(1,2,3,4);
$c = array(); //result set
if(count($a) == count($b)){ // make sure they are the same length
for($i = 0; $i < count($a); $i++){
$c[] = $a[$i]."-".$b[$i];
}
}
print_r($c);
If i understand right, you can use array_combine where array 1 will be the key and array 2 the value.
Example usage:
$a = array(1,2,3,4);
$b = array(a,b,c,d);
$c = array_combine($a, $b);
var_dump($c);
I am reading value from CMD which is running a python program and my output as follows:
Let as assume those values as $A:
$A = [[1][2][3][4]....]
I want to make an array from that as:
$A = [1,2,3,4....]
I had tried as follows:
$val = str_replace("[","",$A);
$val = str_replace("]","",$val);
print_r($val);
I am getting output as:
Array ( [0] => 1 2 3 4 ... )
Please guide me
try this
// your code goes here
$array = array(
array("1"),
array("2"),
array("3"),
array("4")
);
$outputArray = array();
foreach($array as $key => $value)
{
$outputArray[] = $value[0];
}
print_r($outputArray);
Also check the example here https://ideone.com/qaxhGZ
This will work
array_reduce($a, 'array_merge', array());
Multidimensional array to single dimensional array,
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($A));
$A = iterator_to_array($it, false);
But, if $A is string
$A = '[[1][2][3][4]]';
$A = explode('][', $A);
$A = array_map(function($val){
return trim($val,'[]');
}, $A);
Both codes will get,
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
This function will work when you do indeed have a multidimensional array, which you stated you have, in stead of the String representation of a multidimensional array, which you seem to have.
function TwoDToOneDArray($TwoDArray) {
$result = array();
foreach ($TwoDArray as $value) {
array_push($result, $value[0]);
}
return $result;
}
var_dump(TwoDToOneDArray([[0],[1]]));
You can transform $A = [[1],[2],[3],[4]] into $B = [1,2,3,4....] using this following one line solution:
$B = array_map('array_shift', $A);
PD: You could not handle an array of arrays ( a matrix ) the way you did. That way is only for managing strings. And your notation was wrong. An array of arrays (a matrix) is declared with commas.
If you have a string like you wrote in the first place you can try with regex:
$a = '[[1][2][3][4]]';
preg_match_all('/\[([0-9\.]*)\]/', $a, $matches);
$a = $matches[1];
var_dump($a);
If $A is a string that looks like an array, here's one way to get it:
$A = '[[1][2][3][4]]';
print "[".str_replace(array("[","]"),array("",","),substr($A,2,strlen($A)-4))."]";
It removes [ and replaces ] with ,. I just removed the end and start brackets before the replacement and added both of them after it finishes. This outputs: [1,2,3,4] as you can see in this link.
This question already has answers here:
How to filter an associative array comparing keys with values in an indexed array?
(12 answers)
Closed 4 months ago.
Here is data
$array = array(
'random' => 1,
'pewpew' => 2,
'temp' => 5,
'xoxo' => 3,
'qweqweqe' => 4,
);
$fields = array('random', 'xoxo', 'temp');
I need to get in result:
$result = array(
'random' => 1,
'xoxo' => 3,
'temp' => 5,
);
I mean keys presence/order from $fields apply to $array.
The question is:
Can I perform this transformation using only array_ functions? (I don't wanna use iteations)
If yes: can you link me function that I need?
(sorry for spelling mistakes)
upd.
PHP 5.2
$result=array_intersect_key($array ,array_flip($fields) );
// little trick required here...
$fields = array('random' => 0, 'xoxo' => 0, 'temp' => 0);
$result = array_intersect_key($array,$fields);
I am always interested in these types of question, where it's about efficient code (both in code-usage and speed). That said, I tried and benchmarked several different methods, and nothing was as efficient and as a simple foreach!
I tried all the solutions posted, and my own array_walk and basic foreach. I ran several test, both with the arrays and fields posted by Miraage, and some with much larger arrays. I also noted anything odd with the results, such as additional values if $fields had values not in $array.
I've ordered it by speed.
FOREACH: 0.01245 sec
$result = array();
foreach ($fields as $k)
{
if (isset($array[$k]))
$result[$k] = $array[$k];
}
ARRAY_DIFF_KEY: 0.01471 sec (unexpected results: additional values)
$result = array_diff_key($fields, $array);
FOREACH (function): 0.02449 sec
function array_filter_by_key($array, $fields)
{
$result = array();
foreach ($fields as $k)
{
if (isset($array[$k]))
$result[$k] = $array[$k];
}
return $result;
}
ARRAY_WALK (by reference): 0.09123 sec
function array_walk_filter_by_key($item, $key, $vars)
{
if (isset($vars[1][$item]))
$vars[0][$item] = $vars[1][$item];
}
$result = array();
array_walk($fields, 'array_walk_filter_by_key', array(&$result, &$array));
LIST/EACH: 0.12456 sec
$result = array();
reset($fields);
while (list($key, $value) = each($fields))
{
if (isset($array[$value]))
$result[$value] = $array[$value];
}
ARRAY_INTERSECT_KEY: 0.27264 sec (incorrect order)
$result = array_intersect_key($array, array_flip($fields));
ARRAY_REPLACE (array_intersect_key second): 0.29409 sec (unexpected results: additional values)
$result = array_replace(
array_fill_keys($fields, false),
array_intersect_key($array, array_flip($fields))
);
ARRAY_REPLACE (two array_intersect_key): 0.33311 sec
$flip = array_flip($fields);
$result = array_replace(
array_intersect_key($flip, $array),
array_intersect_key($array, $flip)
);
ARRAY_WALK (set null): 3.35929 sec (unexpected results: additional values)
function array_walk_filter_by_key_null(&$item, $key, $array)
{
if (isset($array[$key]))
$item = $array[$key];
else
$item = null;
}
$result = array_flip($fields);
array_walk($result, 'array_walk_filter_by_key_null', $array);
ARRAY_REPLACE (array_intersect_key first): 11.11044 sec
$flip = array_flip($fields);
$result = array_intersect_key(
array_replace($flip, $array),
array_intersect_key($flip, $array)
);
ARRAY_MERGE: 14.11296 sec (unexpected results: additional values)
$result = array_splice(
array_merge(array_flip($fields), $array),
0,
count($fields)
);
So there it is. Can't beat a DIY. Sometimes the perception is that the built-in functions are faster, but it's not always the case. Compilers are pretty good these days.
This code preserves order and works in PHP 5.2 as required
One line:
$result = array_merge( array_flip($fields),
array_intersect_key(
$array,
array_flip( $fields )
)
);
For performance:
$flip = array_flip($fields);
$result = array_merge( $flip
array_intersect_key(
$array,
$flip
)
);
I believe this works as you require.
$result = array_splice(array_merge(array_flip($fields) , $array) , 0 , count($fields));
Just to solve the puzzle:
$result = array_replace(
array_intersect_key(array_flip($fields), $array),
array_intersect_key($array, array_flip($fields))
);
The first array_intersect creates the list of fields in good order, the other one overcomes array_replace functionality to create the the keys that do not exist in the first array.
Meets your requirements. But I wouldn't use it in any production code, as this may be pretty heavy (I didn't benchmark though, so it's just a gut feeling). An array_walk solution seems lighter.
If you want to keep key order from $fields, you could try this: (if key not exists in $array, then the value for that key will be null.)
$result = array_flip($fields);
array_walk($result, function(&$item, $key, $array) {
$item = isset($array[$key]) ? $array[$key] : null;
}, $array);
var_dump($result);
I will consider that you can't change the input (neither $array or $fields).
This can be achieved if you have an array that uses as keys the values from $fields. After that you can merge the two (with $fields being the first parameter) and remove the extra elements.
Considering that you can't change $fields, I will create it:
$tmp = array_combine($fields, range(1, count($fields)));
$result = array_merge($tmp, $array);
$result = array_splice($result, 0, count($fields));
The full working sample (with some comments) can be found here: http://codepad.org/H0CDN7ok
My attempt:
array_replace(
array_fill_keys($fields, false),
array_intersect_key($array, # Keys in array, without order
array_flip($fields))));
It was easy to get the keys in the same order as $array. Then to get them in the proper order, I built an array with keys equal to $fields. Array_replace did the rest.
The solution is "stable" in that missing keys in $array will be replaced with FALSE and can thus be filtered out if need be.
array_flip walks the field array of size N once, array_intersect walks M time a N sized array, array_fill_keys costs N and the final array_replace is, I believe, N^2.
So total cost is M*N^5.
Walking the smallest array and picking the values from the large one is O(M^2*N^2), so for large values of N I suspect that the PHP solution might prove faster. This doesn't enter keys which are not in the data array.
$answer = array();
foreach($fields as $fld) // N-sized cycle
if (isset($array[$fld])) // Cost M
$answer[$fld] = // Assignment is N*1/2
$array[$fld]; // Getting value is another M
(some time and much puzzlement later)
I ran a check and I think I must be making some silly mistake, for the times I'm getting are totally nonsensical. Admittedly I'm using a very short $fields array, so I'd expect skewed results, but not this skewed. Unless $answer[$fld] is calculated with some REALLY clever hash trick, whereby the true cost of the interpreted solution is not O(M^2*N^2) but O(K*N^2) with K small.
If anyone wants to play with times or tell me what stupid mistake I might have made, here's the benchmark.
I was of two minds about posting this, because the other obvious explanation is that I made a ridiculous, silly mistake somewhere and I'm going to end up with egg on my face, but, oh, what the hell.
$array = array(
'random' => 1,
'pewpew' => 2,
'temp' => 5,
'xoxo' => 3,
'qweqweqe' => 4,
);
$fields = array('random', 'xoxo', 'temp');
// Let's not print anything just yet, maybe that's what screwing the timer?
$results = '';
$duh = 0;
for ($cycle = 0; $cycle < 10; $cycle++)
{
// Add some more elements to $array.
for ($i = 0; $i < 10000; $i++)
{
$k = uniqid();
$array[$k] = 42;
}
$start = explode(' ', microtime());
// WTF? Do more cycles to average the timing.
for ($j = 0; $j < 10; $j++)
{
// 0 or 1 to switch
if (1)
{
// INTERPRETED ANSWER
$answer = array();
foreach($fields as $fld) // N-sized cycle
if (isset($array[$fld])) // Cost M
$answer[$fld] = // Assignment is N*1/2
$array[$fld]; // Getting value is another M
} else {
// FUNCTION ANSWER
$answer = array_replace(
array_fill_keys($fields, false),
// array_combine($fields, $fields),
array_intersect_key($array, # Keys in array, without order
array_flip($fields)));
}
// USE $answer so to avoid premature optimization?
// You can't be that clever.
$duh += strlen(serialize($answer));
}
$stop = explode(' ', microtime());
// An error in timing? Check via a stupid roundabout.
$int = $stop[1]-$start[1]+1;
$int += ($stop[0]-$start[0]);
$int -= 1;
$elapsed = number_format($int * 1000000, 2);
$results .= "".(5000*$cycle)." = $elapsed us.\n";
}
// I need to get in result:
$wanted = array(
'random' => 1,
'xoxo' => 3,
'temp' => 5,
);
// DID we get the right answer?
print "Wanted:\n"; print_r($wanted);
print "Gotten:\n"; print_r($answer);
print "Results: $results\n$duh -- count of array is " . count($array);
// And yet I have always the same realtime, name of a dog, how can that be?
// I must be doing something REALLY REALLY wrong somewhere.
Easy Way:
$array = array(
'random' => 1,
'pewpew' => 2,
'temp' => 5,
'xoxo' => 3,
'qweqweqe' => 4,
);
$fields = array('random', 'xoxo', 'temp');
$output = array();
foreach ($fields as $value)
if(isset($array[$value]))
$output[$value]=$array[$value];
This is a solution that also handles the case when some $fields are not present as keys in $array:
$flip = array_flip($fields);
$result = array_intersect_key(array_replace($flip, $array), array_intersect_key($flip, $array));
If all $fields are known to be present as keys in $array there is this simpler solution:
$flip = array_flip($fields);
$result = array_intersect_key(array_replace($flip, $array), $flip);
which can be written as a one-liner like this:
$result = array_intersect_key(array_replace($flip=array_flip($fields), $array), $flip);
If some $fields are not keys of $array, but $array contains counts, so that it makes sense to return a 0 count for missing keys, we can replace flip() with array_fill_keys($fields, 0):
$result = array_intersect_key(array_replace($fill=array_fill_keys($fields, 0), $array), $fill);
to which we can apply an array_filter() to filter out the 0s again, if needed. By replacing 0 with false or null we can flag and handle the absence of a key in $array when the values are not counts.
The sad thing is that these solutions, like all others on this page, have to work through all keys of the $array, while any explicit loop would be on $fields. For the time being, it seems that when count($array) is much bigger than count($fields) there is no array-function-based solution as fast as an explicit loop (since they would explicitly construct the result in callback functions, I consider array_walk() and array_reduce() to be explicit loops here).
The problem is that none of the available array_ functions breaks the association between keys and values, and since we would like to loop on $fields, or rather a flipped array thereof, also to conserve its sort order, while keeping the values of $array, we are out of luck.
try:
$result=array();
reset($fields);
while(list($key,$value)=each($fields))
{
if(isset($array[$value])) $result[$value]=$array[$value];
}
This will work and preserve order for you:
$fields = array_flip($fields);
array_merge($fields,array_intersect_key($array, $fields));
$fields = array_keys($fields);
note, you could just call array_flip twice, but the above seemed a bit "cleaner".
The PHP function is called array_diff_key.
Sample code:
$array = array(
'random' => 1,
'pewpew' => 2,
'temp' => 5,
'xoxo' => 3,
'qweqweqe' => 4
);
$fields = array('random', 'xoxo', 'temp');
$result = array_diff_key($fields, $array);
This will produce the desired result.
Demo: http://shaquin.tk/experiments/array1.php
EDIT: If $fields can contain a value that is not a key in $array, then use this code:
$result = array_diff_key($fields, $array);
$result = array_intersect_key(array_flip($fields), $array);
$result = array_flip(array_diff(array_keys($result), $array));
$result = array_replace($result, $array);
$result = array_flip(array_intersect(array_flip($result), $fields));
It may be possible to optimize this a bit, but it works!
Note: I cannot link to an example, since my (hosted) site doesn't have >= PHP 5.3, however, I can link to a similar one: http://shaquin.tk/experiments/array2.php.
There are 2 arrays, both with the same length and with the same keys:
$a1 = [1=>2000,65=>1354,103=>1787];
$a2 = [1=>'hello',65=>'hi',103=>'goodevening'];
asort($a1);
The keys of a1 and a2 are id's from a database.
a1 gets sorted by value. Once sorted, how can we use the same sorting order in a2?
Thanks!
I believe this works:
$a1 = array(1=>2000,65=>1354,103=>1787);
$a2 = array(1=>'hello',65=>'hi',103=>'goodevening');
asort($a1); // sort $a1, maintaining array index
// sort $a2 by key, using the order of $a1
function my_uksort($a, $b) {
global $a1;
return $a1[$a] < $a1[$b] ? -1 : 1;
}
uksort($a2, 'my_uksort');
var_dump($a1);
var_dump($a2);
Not optimal maybe.. but it's short:
$a1 = array(1=>2000,65=>1354,103=>1787);
$a2 = array(1=>'hello',65=>'hi',103=>'goodevening');
asort($a1);
foreach(array_keys($a1) as $i) $out[$i] = $a2[$i];
echo join("\n", $out);
look into uasort() also
foreach($a1 as $key => $value){
//do something with $a2
echo $a2[$key];
}
You probably want to look at array_multisort() if you can handle losing ID association (arrays will be re-indexed).
array_multisort($a1, $a2);