Topic: [SOLVED] Manipulate array (remove certain keys and renaming keys)

[lindm]

I have the following array:

Code: [Select]

$array = array(
'FIGURE1cy'=>100,
'FIGURE1py'=>100,
'FIGURE2cy'=>100,
'FIGURE2py'=>100 ,
'somethingelse'=>hello,
'somethingelse2'=>hello2

etc
etc
);
I am looking for two ways to manipulate this array:
1. Remove all elements where the key ends with cy. I could use unset but there must be a simpler way since the array is fairly large. Some way to iterate through the array with unset??

2. Perform number 1 and change the name of all keys ending with cy to py.

Any help appreciated.

[Mark Baker]

Looping through the array and using unset is probably the easiest method, but array_walk() provides you with an alternative.

<?php

$array = array( 'FIGURE1cy'      => 100,
                'FIGURE1py'      => 100,
                'FIGURE2cy'      => 100,
                'FIGURE2py'      => 100 ,
                'somethingelse'  => 'hello',
                'somethingelse2' => 'hello2'
);


function arrayWalkFunc($item1, $key, $array) {

if (substr($key,-2) == 'cy') {

unset($array[$key]);

}
}

array_walk($array,'arrayWalkFunc',&$array);

echo '<pre>';
print_r($array);
echo '</pre>';

?>

[lindm]

Thanks!

Any suggestion if I want to rename all keys ending with cy to py?

[Mark Baker]

Any suggestion if I want to rename all keys ending with cy to py?

You could use the same basic technique.

However, that would cause problems with your test array, where you already have a key ending in 'py' that matches one of the 'cy' keys that you want to rename.


<?php

$array = array( 'FIGURE1cy'      => 100,
                'FIGURE1py'      => 100,
                'FIGURE2cy'      => 100,
                'FIGURE2py'      => 100 ,
                'somethingelse'  => 'hello',
                'somethingelse2' => 'hello2'
);


function arrayWalkFunc($item1, $key, $array) {

if (substr($key,-2) == 'cy') {

$newkey = substr($key,0,-2).'py';

unset($array[$key]);

$array[$newkey] = $item1;

}
}

array_walk($array,'arrayWalkFunc',&$array);

echo '<pre>';
print_r($array);
echo '</pre>';

?>


And again, a straight loop would be a better approach.

[lindm]

Is there a good example with a straight loop?

Thanks

[Barand]

Just one problem

Users may not change the array itself from the callback function. e.g. Add/delete elements, unset elements, etc.

[Mark Baker]

Just one problem

Users may not change the array itself from the callback function. e.g. Add/delete elements, unset elements, etc.

Except my examples actually work because I'm explicitly passing the third parameter to array_walk() by reference;

[lindm]

Would it be possible to use array_map and unset somehow?

Code: [Select]

$array=$_POST;


function remove($item) {
if (substr($item,-2) == 'py') {
unset($item);
}
}



$b = array_map("remove", $_POST);

echo json_encode($b);

[premiso]

Code: [Select]

function remove(&$item) {
  foreach ($item as $key => $val) {
       if (substr($key,-2) == 'py') {
           unset($item[$key]);
       }
  }
}



$b = array_map("remove", $_POST);

echo json_encode($b);

I think that would work. You have to pass it by reference from what I remember....

[lindm]

Tried this:

Code: [Select]

$array = array(
'FIGURE1cy'=>100,
'FIGURE1py'=>100,
'FIGURE2cy'=>100,
'FIGURE2py'=>100 ,
'somethingelse'=>hello,
'somethingelse2'=>hello2
);


function remove(&$item) {
  foreach ($item as $key => $val) {
       if (substr($key,-2) == 'py') {
           unset($item[$key]);
       }
  }
}



$b = array_map("remove", $array);

echo json_encode($b);
But get the error:

Code: [Select]

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21

Warning: Invalid argument supplied for foreach() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 21
{"FIGURE1cy":null,"FIGURE1py":null,"FIGURE2cy":null,"FIGURE2py":null,"somethingelse":null,"somethingelse2":null}

[premiso]

Code: [Select]

function remove($item) {
  if (is_array($item)) {
     foreach ($item as $key => $val) {
          if (substr($key,-2) == 'py') {
             unset($item[$key]);
         }
     }
      return $item;
  }
}


$b = remove($_POST);


echo json_encode($b);

Should work as long as $_POST is an array, so make sure you are posting data.

[lindm]

Seems to work! Now I have a follow up for another function...

I want to rename all keys ending with "cy" to "py". So

Code: [Select]

$array = array(
'FIGURE1cy'=>100,
'FIGURE2cy'=>100,
'somethingelse'=>hello,
'somethingelse2'=>hello2
);
would become

Code: [Select]

$array = array(
'FIGURE1py'=>100,
'FIGURE2py'=>100,
'somethingelse'=>hello,
'somethingelse2'=>hello2
);
My code so far (based on your code above):

Code: [Select]

function rename($item) {
  if (is_array($item)) {
     foreach ($item as $key => $val) {
          if (substr($key,-2) == 'cy') {
             XXXXXX
         }
     }
      return $item;
  }
}




$b = rename($array);

echo json_encode($b);
Not sure about the XXXX or if this is the best way to handle the problem?

[premiso]

Code: [Select]

function rename($item) {
  if (is_array($item)) {
     foreach ($item as $key => $val) {
          if (substr($key,-2) == 'cy') {
             $key = str_replace("cy", "py", $key);
             $item[$key] = $val;
         }
     }
      return $item;
  }
}


$b = rename($array);

echo json_encode($b);


[lindm]

When testing:

Code: [Select]

$array = array(
'FIGURE1cy'=>100,
'FIGURE2cy'=>100,
'somethingelse'=>hello,
'somethingelse2'=>hello2
);

function rename($item) {
  if (is_array($item)) {
     foreach ($item as $key => $val) {
          if (substr($key,-2) == 'cy') {
             $key = str_replace("cy", "py", $key);
             $item[$key] = $val;
         }
     }
      return $item;
  }
}


$b = rename($array);

echo json_encode($b);
Gives the following error:

Code: [Select]

Fatal error: Cannot redeclare rename() in /Library/WebServer/Documents/htdocs/phptest2/script/jsonnewyear.php on line 36

[premiso]

You have the function defined somewhere else. Comment out the old function or rename that one to replace or something like that