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Find highest value
(PHP 4, PHP 5)
Example 1150. Example uses of max()<?phpRelated Examples ( Source code ) » max Examples ( Source code ) » Use form to add data to database Examples ( Source code ) » Get column name, type and max length Examples ( Source code ) » A File Upload Examples ( Source code ) » Quantifier Syntaxes Examples ( Source code ) » User Registration Form Demo Examples ( Source code ) » A Dynamic Bar Chart Examples ( Source code ) » Addendum Examples ( Source code ) » The trinary operator Examples ( Source code ) » max_execution_time Examples ( Source code ) » Port scan Examples ( Source code ) » Creating a simple line graph - ImagickDraw Examples ( Source code ) » Search the Web using Google API Examples ( Source code ) » Get WhoIs Information for 270 different tld's Examples ( Source code ) » HttpResponse supports a basic throttling mechanism Examples ( Source code ) » Download big file using HttpRequest Code Examples / Notes » maxjohnmott59
To find the maximum value from a set of 1-dimensional arrays, do this: $d1 = array(450,420,440,430,421); $d2 = array(460,410,410,430,413,375,256,411,656); $d3 = array(430,440,470,435,434,255,198); $t = max(max($d1),max($d2),max($d3)); // $t is 656 The inner max() functions operate on the arrays, the outer max compares the numeric results of the inner ones. joan dot codina
This is highly ineficient, but can be a bit better <? function doublemax($mylist){ $maxvalue=max($mylist); while(list($key,$value)=each($mylist)){ if($value==$maxvalue) return array("key"=>$key,"value"=>$value); } } ?> mick
There are a couple of things you can do for cleaner code if you want the keys returned from the array. I am not sure how they each impact performance, but the visual readability is more beneficial for me -- your mileage may vary. In the first example keys and max value is returned: <?php // First, let's pretend we have an array like this: $Some_Array = array( 'john' => 40, 'susan' => 40, 'jane' => 24, 'michael' => 19, 'jimmy' => 38 ); function max_extract($My_Array) { $Max_Value = max($My_Array); return array_fill_keys(array_keys($My_Array, $Max_Value), $Max_Value); } // ! max_extract() ?> Or, if you are only interested in the keys and don't care what the max is: <?php function max_extract($My_Array) { return array_keys($My_Array, max($My_Array)); // You can also array_flip() this is you want them as keys // or if some other reason makes this relevant/needed. } // ! max_extract() ?> There are many possible variations when using the search parameter of array_keys() along with other array functions. johnphayes
Regarding boolean parameters in min() and max(): (a) If any of your parameters is boolean, max and min will cast the rest of them to boolean to do the comparison. (b) true > false (c) However, max and min will return the actual parameter value that wins the comparison (not the cast). Here's some test cases to illustrate: 1. max(true,100)=true 2. max(true,0)=true 3. max(100,true)=100 4. max(false,100)=100 5. max(100,false)=100 6. min(true,100)=true 7. min(true,0)=0 8. min(100,true)=100 9. min(false,100)=false 10. min(100,false)=false 11. min(true,false)=false 12. max(true,false)=true sta
Or to take multiple maximum values into consideration: function doublemax($mylist){ $maxvalue=max($mylist); $max_keys = array(); while(list($key,$value)=each($mylist)){ if($value==$maxvalue) array_push($max_keys,$key); } return $max_keys; } mikhail_kovalev
Note that in version 4.0.3 (the only version I tested): max (0, 0); // returns 0. max (0, false); // returns 0. max (false, 0); // returns false. max (false, false); // returns false. As a solution use this: (int) max (false, 0); // returns 0. (int) max (false, false); // returns 0. jeremi23
max on a an array with key/values <? $tmp = array(1 => 5, 2=> 3); echo max($tmp); ?> this return 5, so the max is done on the values. michaelangel0
Matlab users and others may feel lonely without the double argument output from min and max functions. To have the INDEX of the highest value in an array, as well as the value itself, use the following, or a derivative: <? function doublemax($mylist){ $maxvalue=max($mylist); while(list($key,$value)=each($mylist)){ if($value==$maxvalue)$maxindex=$key; } return array("m"=>$maxvalue,"i"=>$maxindex); } ?> tim
In response to the previous two posters (zher0 at netcarrier dot com & walkingmantis): I was trying to do exactly what zher0 suggested; calculate the max value of a multi-dimensional array with variably sized 'sub-arrays'. Here is a simple little function I came up with to do just that: <?php function multimax( $array ) { // use foreach to iterate over our input array. foreach( $array as $value ) { // check if $value is an array... if( is_array($value) ) { // ... $value is an array so recursively pass it into multimax() to // determine it's highest value. $subvalue = multimax($value); // if the returned $subvalue is greater than our current highest value, // set it as our $return value. if( $subvalue > $return ) { $return = $subvalue; } } elseif($value > $return) { // ... $value is not an array so set the return variable if it's greater // than our highest value so far. $return = $value; } } // return (what should be) the highest value from any dimension. return $return; } ?> Please note that I have only performed very limited testing on this code -- be sure to check it thoroughly if you implement it somewhere! nonick
If you are working with numbers, then you can use: $a = ($b > $c) ? $b : $c; which is somewhat faster (roughly 16%) than $a = max($b, $c); I tested this on several loops using integers and floats, over 1 million iterations. I'm running PHP 4.3.1 as a module for Apache 1.3.27. |
