Php 如何删除多维数组中的重复元素？
我有一个类似这样的json文件。它每年都有流行歌曲。稍后我将使用这些歌曲创建基于十年的播放列表Php 如何删除多维数组中的重复元素？,php,arrays,multidimensional-array,Php,Arrays,Multidimensional Array,我有一个类似这样的json文件。它每年都有流行歌曲。稍后我将使用这些歌曲创建基于十年的播放列表 { "1940": [ { "artist": "Tommy Dorsey", "title": "I'll Never Smile Again" }, { "artist": "Bing Crosby", "title": "Only Forever
{
"1940": [
{
"artist": "Tommy Dorsey",
"title": "I'll Never Smile Again"
},
{
"artist": "Bing Crosby",
"title": "Only Forever"
},
{
"artist": "Artie Shaw",
"title": "Frenesi"
},
{
"artist": "Glenn Miller",
"title": "The Nearness of You"
},
{
"artist": "Artie Shaw",
"title": "Frenesi"
},
{
"artist": "Tommy Dorsey & Frank Sinatra",
"title": "Imagination"
},
{
"artist": "Cliff Edwards (Ukelele Ike)",
"title": "When You Wish Upon a Star"
},
{
"artist": "Bing Crosby",
"title": "Sierra Sue"
},
{
"artist": "The Ink Spots",
"title": "Java Jive"
},
{
"artist": "Jimmy Dorsey",
"title": "6 Lessons From Madame La Zonga"
},
{
"artist": "Jimmie Davis",
"title": "You Are My Sunshine"
},
{
"artist": "Bob Wills & his Texas Playboys",
"title": "New San Antonio Rose"
},
{
"artist": "Tommy Dorsey",
"title": "Stardust"
},
{
"artist": "The Andrews Sisters",
"title": "Beat Me Daddy, Eight To The Bar"
},
{
"artist": "Charlie Barnet",
"title": "Pompton Turnpike"
},
{
"artist": "Judy Garland",
"title": "I'm Nobody's Baby"
},
{
"artist": "Bob Crosby & his Orchestra",
"title": "Down Argentina Way"
},
{
"artist": "Kate Smith",
"title": "The Woodpecker Song"
},
{
"artist": "Shep Fields & his Rippling Rhythm Orchestra",
"title": "Down Argentina Way"
},
{
"artist": "Vaughn Monroe",
"title": "There I Go"
},
{
"artist": "Will Bradley",
"title": "There I Go"
},
{
"artist": "Mitchell Ayres & his Fashions in Music",
"title": "Make Believe Island"
},
{
"artist": "Joe Loss Orchestra",
"title": "Beer Barrel Polka (Roll out the Barrel)"
},
{
"artist": "Carson Robison",
"title": "South of the Border (Down Mexico Way)"
},
{
"artist": "Francisco Alves",
"title": "Dama das Camelias"
},
{
"artist": "Duke Ellington",
"title": "Ko Ko"
},
{
"artist": "Bill Monroe",
"title": "Mule Skinner Blues"
},
{
"artist": "Bukka White",
"title": "Special Stream Line"
},
{
"artist": "Tony Martin",
"title": "It's a Blue World"
},
{
"artist": "Orlando Silva",
"title": "Suplica"
},
{
"artist": "Ella Fitzgerald",
"title": "Five O'Clock Whistle"
},
{
"artist": "Edith Piaf",
"title": "L'accordeoniste"
},
{
"artist": "Erskine Hawkins",
"title": "Dolemite"
},
{
"artist": "Dick Robertson & his Orchestra",
"title": "Ma (He's Making Eyes At Me)"
},
{
"artist": "Kay Kyser",
"title": "Playmates"
},
{
"artist": "Nat Gonella",
"title": "I'm Nobody's Baby"
},
{
"artist": "Bando da Lua",
"title": "O Samba da Minha Terra"
},
{
"artist": "Cyro Monteiro",
"title": "Oh! Seu Oscar"
},
{
"artist": "Roland Hayes",
"title": "Were You There?"
},
{
"artist": "Benny Goodman",
"title": "Seven Come Eleven"
},
{
"artist": "Sammy Kaye",
"title": "Dream Valley"
},
{
"artist": "Bob Chester & his Orchestra",
"title": "Practice Makes Perfect"
},
{
"artist": "Frank Proffitt",
"title": "Tom Dooley"
},
{
"artist": "Art Tatum",
"title": "Sweet Lorraine"
},
{
"artist": "Dircinha Batista",
"title": "Upa! Upa! (Meu Trolinho)"
},
{
"artist": "Connee Boswell",
"title": "On the Isle of May"
},
{
"artist": "Aracy de Almeida",
"title": "Passarinho do Relogio (Cuco)"
}
],
"1941": [
{
"artist": "Glenn Miller",
"title": "Chattanooga Choo Choo"
},
{
"artist": "Artie Shaw",
"title": "Frenesi"
},
{
"artist": "Jimmy Dorsey",
"title": "Blue Champagne"
},
{
"artist": "Sammy Kaye",
"title": "Daddy"
},
{
"artist": "Freddy Martin",
"title": "Piano Concerto in B Flat"
},
{
"artist": "Glenn Miller",
"title": "Adios"
},
{
"artist": "Sammy Kaye",
"title": "Daddy"
},
{
"artist": "Artie Shaw",
"title": "Blues in the Night"
},
{
"artist": "Billie Holiday",
"title": "God Bless the Child"
},
{
"artist": "Jimmy Dorsey",
"title": "Jim"
},
{
"artist": "The Andrews Sisters",
"title": "I'll Be With You in Apple Blossom Time"
},
{
"artist": "Duke Ellington",
"title": "I Got it Bad & That Ain't Good"
},
{
"artist": "Horace Heidt",
"title": "G'bye Now"
},
{
"artist": "Freddy Martin",
"title": "The Hut Sut Song (A Swedish Serenade)"
},
{
"artist": "The Ink Spots",
"title": "I Don't Want to Set the World On Fire"
},
{
"artist": "Harry James",
"title": "Music Makers"
},
{
"artist": "Tommy Dorsey & Frank Sinatra",
"title": "This Love of Mine"
},
{
"artist": "The Sons of the Pioneers",
"title": "Cool Water"
},
{
"artist": "Benny Goodman",
"title": "Solo Flight"
},
{
"artist": "Xavier Cugat",
"title": "Chica, Chica, Boom, Chic"
},
{
"artist": "Ernest Tubb",
"title": "Walking the Floor Over You"
},
{
"artist": "Guy Lombardo",
"title": "And the Band Played On"
},
{
"artist": "Vera Lynn",
"title": "A Nightingale Sang in Berkeley Square"
},
{
"artist": "Dick Robertson",
"title": "Ferryboat Serenade"
},
{
"artist": "The Jesters",
"title": "It's a Great Day for the Irish"
},
{
"artist": "The Tic-Toc Rhythm Orchestra",
"title": "Ferryboat Serenade"
},
{
"artist": "Judy Garland",
"title": "It's a Great Day for the Irish"
},
{
"artist": "Francisco Alves",
"title": "Canta Brasil"
},
{
"artist": "George Formby",
"title": "Bless 'em All (The Service Song)"
},
{
"artist": "Al Bowlly",
"title": "When That Man is Dead & Gone"
},
{
"artist": "Bing Crosby",
"title": "Shepherd's Serenade"
},
{
"artist": "Tommy Dorsey",
"title": "Do I Worry?"
},
{
"artist": "Charlie Barnet",
"title": "I Hear A Rhapsody"
},
{
"artist": "Wayne King",
"title": "You Are My Sunshine"
},
{
"artist": "Gene Krupa",
"title": "It All Comes Back To Me Now"
},
{
"artist": "Big Maceo Merriweather",
"title": "Worried Life Blues"
},
{
"artist": "Big Bill Broonzy",
"title": "Key to the Highway"
},
{
"artist": "Joe Loss Orchestra",
"title": "'V' Stands For Victory"
},
{
"artist": "Carlos Galhardo",
"title": "Ala Li La"
},
{
"artist": "Tommy Tucker",
"title": "I Don't Want to Set the World On Fire"
},
{
"artist": "Kay Kyser",
"title": "Alexander the Swoose (Half Swan, Half Goose)"
},
{
"artist": "Al Donahue",
"title": "The Wise Old Owl"
},
{
"artist": "Woody Herman",
"title": "Blue Flame"
},
{
"artist": "Washboard Sam",
"title": "She Belongs to The Devil"
},
{
"artist": "Dorival Caymmi",
"title": "O Mar"
},
{
"artist": "Ray Noble",
"title": "By the Light of the Silvery Moon"
},
{
"artist": "Joel & Gaucho",
"title": "Aurora"
},
{
"artist": "Jay McShann",
"title": "Vine Street Blues"
}
]
}
<?php
$decade = file_get_contents("decade.json");
$decade = json_decode($decade, true);
foreach($decade as $key => $year) {
foreach($year as $k => $item) {
$title = $item["title"];
$artist = $item["artist"];
$i = 0;
foreach($year as $kkk => $it) {
if ($it["title"] = $title) {
unset($decade[$key][$kkk]);
//echo "found";
}
$i = $i + 1;
}
}
}
echo json_encode($decade);
?>
在IF语句中用于字符串之间比较的条件不正确。你应使用： （$it[“title”]==$title） 而不是： （$it[“title”]=$title）方法（在检查“重复项”时有点过度）
- 按年份、艺术家、标题阅读“歌曲源阵列”
- 如果不是重复条目，则将其添加到输出数组中
in_array- 年
- 分隔符“|”
- 小写艺术家
- 分隔符“|”
- 小写标题
- 然后转换为SHA1散列
$outSongs=array（）；
$outDuplicates=array（）；
//避免对大型阵列进行昂贵的“阵列内”扫描。。。需要对其进行基准测试
//创建“年”、“艺术家”和“头衔”的“签名”作为“钥匙”，以便我们
//可以快速检查它是否存在于阵列中。
$songsigniters=array（）；
foreach（$sourceas$year=>$yearSongs）{//songs by year。。。
foreach（$yearSongs作为$songDetails）{//一年的所有歌曲
$artist=$songDetails['artist']；
$title=$songDetails['title']；
//生成可以快速检查但唯一的“密钥”。
//使其不区分大小写。
$songSig=sha1（$year.'|'）.strtolower（$artist.'|'.strtolower（$title））；
如果（！isset（$songsigniters[$songSig]）{//添加到输出。。。
$songsigniters[$songSig]=真；
$outSongs[$year][]=$songDetails；
}
else{//存储副本以备以后检查
$outDuplicates[$year][]=$songDetails；
}
}
}
回声'；
印刷品（外松）；
回声'；
回声'；
打印（复印件）；
回声'；
/*
回声'；
印刷（签名）；
回声'；
*/
$outSongs = array();
$outDuplicates = array();
// Avoid 'in_array' scans which are expensive for large arrays... need to benchmark it
// Create a 'signature' of 'year', artist and title as a 'key' so we
// can check it exists in the array quickly.
$songSignitures = array();
foreach($source as $year => $yearSongs) { // songs by year...
foreach ($yearSongs as $songDetails) { // all the songs for one year
$artist = $songDetails['artist'];
$title = $songDetails['title'];
// generate a 'key' that can be checked quickly but is unique.
// make it lettercase insensitive.
$songSig = sha1($year .'|'. strtolower($artist) .'|'. strtolower($title));
if (!isset($songSignitures[$songSig])) { // add to the output...
$songSignitures[$songSig] = true;
$outSongs[$year][] = $songDetails;
}
else { // store duplicates for checking later
$outDuplicates[$year][] = $songDetails;
}
}
}
echo '<pre>';
print_r($outSongs);
echo '</pre>';
echo '<pre>';
print_r($outDuplicates);
echo '</pre>';
/*
echo '<pre>';
print_r($songSignitures);
echo '</pre>';
*/