Shuffle Array Elements by Rearranging the Key Value Associations (PHP)
PHP's shuffle()
function destroys the array keys, so I decided to write a shuffle function that doesn't do that and instead rearranges key-value associations. As I would be using the function in place of shuffle()
most of the time, I'd like it to be as fast and memory efficient (if a time-space tradeoff is needed, I think I would prioritise time) as possible:
My Code
<?
function swap(&$a, &$b)
{
$tmp = $a;
$a = $b;
$b = $tmp;
}
function shuffleX(&$arr) #Shuffles the key-value associations in an array.
{
$keys = array_keys($arr); #extract the keys from the array.
$length = count($keys);
$i = 0; #Index.
while ($i < $length-1)
{
$target = rand(($i+1), $length-1); #This ensures that no value ends up mapped to the same key.
swap($arr[$keys[$i]], $arr[$keys[$target]]); #Swap each element of the array with another.
$i++;
}
}
?>
performance beginner php array
add a comment |
PHP's shuffle()
function destroys the array keys, so I decided to write a shuffle function that doesn't do that and instead rearranges key-value associations. As I would be using the function in place of shuffle()
most of the time, I'd like it to be as fast and memory efficient (if a time-space tradeoff is needed, I think I would prioritise time) as possible:
My Code
<?
function swap(&$a, &$b)
{
$tmp = $a;
$a = $b;
$b = $tmp;
}
function shuffleX(&$arr) #Shuffles the key-value associations in an array.
{
$keys = array_keys($arr); #extract the keys from the array.
$length = count($keys);
$i = 0; #Index.
while ($i < $length-1)
{
$target = rand(($i+1), $length-1); #This ensures that no value ends up mapped to the same key.
swap($arr[$keys[$i]], $arr[$keys[$target]]); #Swap each element of the array with another.
$i++;
}
}
?>
performance beginner php array
add a comment |
PHP's shuffle()
function destroys the array keys, so I decided to write a shuffle function that doesn't do that and instead rearranges key-value associations. As I would be using the function in place of shuffle()
most of the time, I'd like it to be as fast and memory efficient (if a time-space tradeoff is needed, I think I would prioritise time) as possible:
My Code
<?
function swap(&$a, &$b)
{
$tmp = $a;
$a = $b;
$b = $tmp;
}
function shuffleX(&$arr) #Shuffles the key-value associations in an array.
{
$keys = array_keys($arr); #extract the keys from the array.
$length = count($keys);
$i = 0; #Index.
while ($i < $length-1)
{
$target = rand(($i+1), $length-1); #This ensures that no value ends up mapped to the same key.
swap($arr[$keys[$i]], $arr[$keys[$target]]); #Swap each element of the array with another.
$i++;
}
}
?>
performance beginner php array
PHP's shuffle()
function destroys the array keys, so I decided to write a shuffle function that doesn't do that and instead rearranges key-value associations. As I would be using the function in place of shuffle()
most of the time, I'd like it to be as fast and memory efficient (if a time-space tradeoff is needed, I think I would prioritise time) as possible:
My Code
<?
function swap(&$a, &$b)
{
$tmp = $a;
$a = $b;
$b = $tmp;
}
function shuffleX(&$arr) #Shuffles the key-value associations in an array.
{
$keys = array_keys($arr); #extract the keys from the array.
$length = count($keys);
$i = 0; #Index.
while ($i < $length-1)
{
$target = rand(($i+1), $length-1); #This ensures that no value ends up mapped to the same key.
swap($arr[$keys[$i]], $arr[$keys[$target]]); #Swap each element of the array with another.
$i++;
}
}
?>
performance beginner php array
performance beginner php array
asked 9 mins ago
Tobi Alafin
1855
1855
add a comment |
add a comment |
0
active
oldest
votes
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
});
});
}, "mathjax-editing");
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "196"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fcodereview.stackexchange.com%2fquestions%2f210790%2fshuffle-array-elements-by-rearranging-the-key-value-associations-php%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
0
active
oldest
votes
0
active
oldest
votes
active
oldest
votes
active
oldest
votes
Thanks for contributing an answer to Code Review Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fcodereview.stackexchange.com%2fquestions%2f210790%2fshuffle-array-elements-by-rearranging-the-key-value-associations-php%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown