在PHP中排序并获取数组中值的频率？

Question

I have an xml file with a list of field titles. I want to store them in an array an sort them alphabetically and then by which "title" appears the most. My actual XML file is huge to copy here (PS: I'm importing from a bunch of XML files).

In a nutshell, this is an example of how the XML files look.

<add overwrite="true">
<docs>

    <field name="id">9637a08df6aa0765</field>
    <field name="url">http://somewebsite.ca </field>
    <field name="blogurl">http://www.someblog.com</field>
    <field name="published">2015-05-21</field>
    <field name="language">English</field>
    <field name="title">Stephen Harper</field>
    <field name="title">Mike Duffy Trial</field>
    <field name="title">POTUS on Twitter</field>
    <field name="title">Tim Hortons Closed</field>
    <field name="title">Stephen Harper</field>
    <field name="title">The New iPhone</field>
    <field name="title">Stephen Harper</field>
</docs>
</add>

So let's say I get the title attribute from the XML file and store them in an array. I then want to sort that array in alphabetical order and then by frequency of the "titles".

This is what I have so far.

<?php

    $titles_array = array();
    $counter = 0; 
    $xml = simplexml_load_file("fields.xml") or die ("Error: Cannot Create Object");

    foreach($xml->docs->field as $fields){
        array_push ($titles_array, $fields);
        echo $fields . "<br>";
        $counter++;  
    }

    echo '<p>' . "Sorted Array" . '</p>';

    sort($titles_array);

    for ($a=0; $a<$counter; $a++){  
        echo $titles_array[$a] . "<br>";
    }

?>

The output is actually not in alphabetical order? Also, how do I get to show the most frequent "title"?

Answer 1

Your $fields is actually going to be the whole SimpleXMLElement inside of your foreach loop. Your arrays will sort as expected if you use this instead:

array_push($titles_array, (string)$fields);

To count the occurrences, create another array:

$titles_count = array();

Then in your loop, do something like this:

if (isset($titles_count[(string)$fields])) {
  $titles_count[(string)$fields] = $titles_count[(string)$fields] + 1;
} else {
  $titles_count[(string)$fields] = 1;
}

Finally, get your key with the highest count like this:

echo array_search(max($titles_count), $titles_count);

Put all that code together like this:

<?php

    $titles_array = array();
    $titles_count = array();
    $xml = simplexml_load_file("fields.xml") or die ("Error: Cannot Create Object");

    foreach($xml->docs->field as $fields){
      array_push ($titles_array, (string)$fields);
      echo $fields . "<br>";

      // First we check if the key exists.
      // Example $titles_count['Tim Hortons Closed']
      if (isset($titles_count[(string)$fields])) {
        // If it does, augment the count by 1;
        $titles_count[(string)$fields] = $titles_count[(string)$fields] + 1;
      } else {
        // If it doesn't yet, set the count to 1;
        $titles_count[(string)$fields] = 1;
      }
    }

    echo "<p>Sorted Array</p>";

    sort($titles_array);

    for ($a=0; $a<$counter; $a++){  
      // Let's put the count in for each one:
      echo $titles_array[$a] . "(" . $titles_count[$titles_array[$a]] . ")" . "<br>";
    }

    echo "<p>Highest key count:</p>";

    // Here we get the value with the highest count use max(...)
    // Then we get it's key (example 'Tim Hortons Closed')
    echo array_search(max($titles_count), $titles_count);

?>