Replace the string made up of another key with the corresponding value, or take the values of multiple arrays at once, how to write this in PHP?

question: 

$s = "1,2,3,4";
$a = [1=>"", 2=>"", 3=>"", 4=>""];

the most important effect to achieve: 

",,,"

above PHP7

Note again: one line of code, one line of code to achieve the effect.

Php
Apr.06,2022

Code 

<?php
$s = "1,2,3,4";
$a = [1=>'', 2=>'', 3=>'', 4=>''];
$arr = [];
foreach (explode(',', $s) as $key) {
    $arr[] = $a[$key];
}
echo implode(',', $arr);

result 

,,,

you can use array functions 

$result = array_map(function ($arrayKey) use ($a) {
    return $a[$arrayKey] ?? null;
}, explode(',', $s));
$result = implode(',', $result);

or 

$result = array_reduce(explode(',', $s), function ($result, $item) use ($a) {
    return $result .= "{$a[$item]},";
}, '');
$result = trim($result, ',');

or 

$result = array_intersect_key($a, array_combine(explode(',', $s), explode(',', $s)));
$result = implode(',', $result);

there is no more concise way. Php does not provide a function to obtain more than one key value at a time, so it can only be encapsulated by itself. The first of the above methods is recommended, with clear logic and high efficiency

Previous: Angular multi-environment configuration problem

Next: If you add check boxes and filters to el-table, there will be conflicts. How to solve them?

css mysql arrays josn react html typescript webpack npm sass R objective-c .net sql-server jquery python-3.x angularjs django angular excel regex iphone ajax linux xml pandas vba spring database wordpress string wpf xcode windows bash postgresql oracle multithreading eclipse list firebase algorithm macos forms image scala visual-studio azure bootstrap spring-boot react-native python-2.7 docker performance function winforms matlab powershell apache dataframe api sqlite numpy rest shell selenium flutter dart maven loops qt swing android-studio csv express file class tensorflow sorting codeigniter perl
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b43a0b-2ba0c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b43a0b-2ba0c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?