Use arsort() to sort the results of array_count_values() in descending order

In PHP, array_count_values() is a very useful function that counts the occurrences of each element in an array and returns an associative array where the key is the array element and the value is the number of occurrences of the element in the array. However, the result returned by array_count_values() is unordered by default. At this time, we can use the arsort() function to arrange the results in descending order, so that we can view the most frequent elements.

This article will explain in detail how to use array_count_values() and array() to process data, and sort the results from high to low frequency.

1. What is array_count_values() ?

The array_count_values() function is used to count the number of occurrences of each element in the array. It returns an associative array where the key is the value in the array and the value is the number of times each value appears.

Sample code:

 <?php
// Define an array
$array = ["apple", "banana", "apple", "orange", "banana", "banana"];

// use array_count_values() Statistical element frequency
$result = array_count_values($array);

// Output result
print_r($result);
?>

Output:

 Array
(
    [apple] => 2
    [banana] => 3
    [orange] => 1
)

In this example, we can see that banana appears 3 times, apple appears 2 times, and orange appears only 1 time.

2. Why do you need to use arsort() ?

The array returned by array_count_values() is unordered, so we need to use arsort() to sort the array and arrange the frequency in descending order, so that the elements with the highest frequency are ranked first. This way, we can easily see which elements appear the most in the array.

The arsort() function sorts the array in descending order by value while maintaining key-value association.

Sample code:

 <?php
// Define an array
$array = ["apple", "banana", "apple", "orange", "banana", "banana"];

// Statistical element frequency
$result = array_count_values($array);

// use arsort() Arrange in descending frequency order
arsort($result);

// Output sorted results
print_r($result);
?>

Output:

 Array
(
    [banana] => 3
    [apple] => 2
    [orange] => 1
)

In the sorted array, banana is at the top because it appears the most times.

3. The practical application of combining array_count_values() and array()

Sometimes we need to count the frequency of occurrence of each character in an array of strings and arrange it in descending order of frequency. Here is a practical example:

 <?php
// Define an array of strings
$text = "php is awesome, php is powerful";

// use str_split() Convert a string to a character array
$charArray = str_split(str_replace(" ", "", $text)); // Remove spaces

// Statistical character frequency
$charCount = array_count_values($charArray);

// Arrange in descending frequency order
arsort($charCount);

// Output sorted results
print_r($charCount);
?>

Output:

 Array
(
    [p] => 4
    [h] => 2
    [i] => 2
    [s] => 2
    [e] => 2
    [o] => 2
    [m] => 1
    [a] => 1
    [w] => 1
    [,] => 1
    [f] => 1
    [u] => 1
)

In this example, we count the frequency of occurrence of each character in the string and use arsort() to sort the characters in descending order of occurrences.

4. Summary

By combining array_count_values() and array() , we can very conveniently count the frequency of elements in the array and arrange them in descending order by frequency. This combination is especially suitable for scenarios where you need to quickly view the number of elements in an array, such as word frequency statistics, character statistics, etc.

Hopefully this article will help you understand how to use these two functions to process data more efficiently. If you have other questions, please continue to discuss it!