I have a dynamically built nested array from which i need to drop one or more indexes.
Having scoured the php information pages, i found that using
unset($quotes_array[0]['methods'][3]);
would remove the last set of data in the array.
But, if i try to use
unset($quotes_array[0]['methods'][0]);
or any other set apart from the last, it messes up the output that is generated from the array.
For instance, if i had a,b,c,d: I can remove d without issue, but if i try to remove a,
i get a blank radio button followed by b,c, with d missing all together when the array data is processed.
I am assuming i need to reindex the array, but every attempt i've made so far has failed to give the required results, most likely because i'm reindexing $quotes_array, whereas the data i actually need to reindex is that within the 'methods' indices.
Is there a way to fix this issue?
unsetting the first element is easy if you use array_shift. array_shift will pop the first element off and reindex your array for you.
array_shift($quotes_array[0]['methods']);
if you need to unset something in the middle (such as [ 2 ] out of [ 3 ]) you could use array_values. First unset the element you want to remove, then reindex them with array_values.
unset($quotes_array[0]['methods'][2]);
array_values($quotes_array[0]['methods']);
if you wanted to remove the last element of an array you could use array_pop. array_pop will pop the last element off the array. There is no need to reindex in this situation.
array_pop($quotes_array[0]['methods']);
try
array_values($quotes_array[0]['methods']);
Related
Which one would you use?
Basically I only want to get the 1st element from a array, that's it.
Well, they do different things.
array_shift($arr) takes the first element out of the array, and gives it to you.
$arr[0] just gives it to you... if the array has numeric keys.
An alternative that works for associative arrays too is reset($arr). This does move the array's internal pointer, but unless you're using those functions this is unlikely to affect you.
array_shift will actually remove the specified value from the array. Do not use it unless you really want to reduce the array!
See here: http://php.net/manual/en/function.array-shift.php
You would use $arr[ 0 ]; array_shift removes the first element from the array.
EDIT
This answer is actually somewhere between incomplete and plain out wrong but, because the comments of the two jon's I think that it should actually stay up so that others can see that discourse.
The right answer:
reset is the method to return the first defined index of the array. Even in non-associative arrays, this may not be the 0 index.
array_shift will remove and return the value which is found at reset
The OP made the assumption that $arr[0] is the first index is not accurate in that particular context.
$arr[0] only works if the array as numerical keys.
array_shift removes the element from the array and it modifies the array itself.
If you are not sure what the first key is , and you do not want to remove it from the array, you could use:
<?php
foreach($arr $k=>$v){
$value = $v;
break;
}
or even better:
<?php
reset($arr);
$value = current($arr);
If you have an associative Array you can also use reset($arr): It returns the first Element (doesn't remove), and sets the array pointer to this element.
But the fastest way is $arr[0].
Do you want to modify the arr array also? array_shift removes the first element of the array and returns it, thus the array has changed. $arr[0] merely gives you the first element.
I would use $arr[0] unless I explicitly wanted to modify the array. You may add code later to use the arr array and forget that it was modified.
given what you need, $arr[0] is preferrable, because it's faster. array_shift is used in other situations.
arrshift is more reliable and will always return the first element in the array, but this also modifies the array by removing that element.
arr[0] will fail if your array doesn't start at the 0 index, but leaves the array itself alone.
A more convoluted but reliable method is:
$keys = array_keys($arr);
$first = $arr[$keys[0]];
with array_shif you have two operations:
retrive the firs element
shift the array
if you access by index, actually you have only one operation.
If you want the first element of an array, use $arr[0] form. Advantages - Simplicity, Readability and Maintainability. Keep things straight forward.
Edit: Use index 0 only if you know that the array has default keys starting from 0.
If you don't want to change the array in question, use $arr[0] (which merely gets the first element), otherwise if you want to remove the first element of $arr from $arr, use array_shift($arr).
For example:
$arr=array(3,-6,2);
$foo=$arr[0]; //$foo==3 and $arr==array(3,-6,2).
$bar=array_shift($arr); //$bar==3 and $arr==array(-6,2).
ETA: As others have pointed out, be sure that your array isn't an associative array (ie the keys are 0,1,...,(sizeof($arr)-1)), otherwise this probably won't work.
When working with existing code, it takes one array and places it into another in the fashion shown below.
I believe the empty brackets are the same thing as simply pushing it and appending it to the first available index.
$g['DATA'][] = $p;
After this is done, I have my own array that I would like to append to this as well. I tried using array_merge() with $g['DATA'][]as a parameter, but this is invalid for obvious reasons.
My only thought is to create a foreach loop counter so I can figure out the actual index it created, however I have to assume there is some cleaner way to do this?
Just simply use the count() of your $g["DATA"] array as index and then you can merge it like this:
$g['DATA'][count($g["DATA"])-1] = array_merge($g['DATA'][count($g["DATA"])-1], $ownArray);
//^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^
// -1 Because an array is based index 0 -> means count() - 1 = last key
Just thought I would like to share this should someone find a use for it.
Basically I needed a list of HTML colors to loop / cycle through. So I need to remove the first element of the array, place it at the end and then get the current HTML color.
Given the following array:
$colors = array(
"#2265fa", "#b61d1e", "#53b822", "#a9d81c", "#d6e9f5", "#43cc7d", "#e3159a",
"#80c85e", "#17b303", "#989240", "#014c07", "#d265f3", "#22bbb9", "#6c69a9",
"#7ea13a", "#0dcea2", "#99c27d", "#41405b", "#731801"
);
So this is what I came up with. Sure there will be hundreds of ways to do this. This is my take on it.
# Array_shift returns the value it takes off the beginning of the array.
# And I merely append this to the end of the array
$colors[] = array_shift($colors);
# Using current I am able to get the current first element of the array back
echo current($colors);
In this case it would be "#b61d1e" that is the current index for the array. May you find this useful somewhere.
I have an array with 18 values in it from which I select random values using $array[rand(0,17)]. I put these randomly selected values next to each other on the page. Within the array are 6 sets of values that I do not want to be put next to each other on the page. Is there any way that I can detect when the pairs are together and select new values because of that
warning: Do you know for sure that you won't get any degenerate cases where there are no possible orderings of the array? For example, if you won't allow the pairs [1,2] or [2,1] and the array you get is [1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2], the you're out of luck. There's no way to display the array in the way you want, and a method like I describe below will never terminate.
I would use shuffle($array) and then iterate through the shuffled array one item at a time, to find out whether any value is "incompatible" with the item before it. If so, just reshuffle the array and try again. You can't predict how many tries it will take to get a shuffled array that works, but the amount of time it takes should be negligible.
To detect whether two values are compatible, I'd suggest making an array that contains all incompatible pairs. For example, if you don't want to have the consecutive pairs 1 and 3 or 2 and 5, then your array would be:
$incompatible = array(
array(1,3),
array(2,5) );
Then you'd iterate over your shuffled array with something like:
for ($i=1; i<count($array)-1; i++;) {
$pair = $array[i, i+1]; // this is why the for loop only goes to the next-to-last item
if in_array($pair, $incompatible) {
// you had an incompatible pair in your shuffled array.
// break out of the for loop, re-sort your array, and try again.
}
}
// if you get here, there were no incompatible pairs
// so go ahead and print the shuffled array!
Or use with unset() for remove the keys, or use by Session, for next skip.
Which one would you use?
Basically I only want to get the 1st element from a array, that's it.
Well, they do different things.
array_shift($arr) takes the first element out of the array, and gives it to you.
$arr[0] just gives it to you... if the array has numeric keys.
An alternative that works for associative arrays too is reset($arr). This does move the array's internal pointer, but unless you're using those functions this is unlikely to affect you.
array_shift will actually remove the specified value from the array. Do not use it unless you really want to reduce the array!
See here: http://php.net/manual/en/function.array-shift.php
You would use $arr[ 0 ]; array_shift removes the first element from the array.
EDIT
This answer is actually somewhere between incomplete and plain out wrong but, because the comments of the two jon's I think that it should actually stay up so that others can see that discourse.
The right answer:
reset is the method to return the first defined index of the array. Even in non-associative arrays, this may not be the 0 index.
array_shift will remove and return the value which is found at reset
The OP made the assumption that $arr[0] is the first index is not accurate in that particular context.
$arr[0] only works if the array as numerical keys.
array_shift removes the element from the array and it modifies the array itself.
If you are not sure what the first key is , and you do not want to remove it from the array, you could use:
<?php
foreach($arr $k=>$v){
$value = $v;
break;
}
or even better:
<?php
reset($arr);
$value = current($arr);
If you have an associative Array you can also use reset($arr): It returns the first Element (doesn't remove), and sets the array pointer to this element.
But the fastest way is $arr[0].
Do you want to modify the arr array also? array_shift removes the first element of the array and returns it, thus the array has changed. $arr[0] merely gives you the first element.
I would use $arr[0] unless I explicitly wanted to modify the array. You may add code later to use the arr array and forget that it was modified.
given what you need, $arr[0] is preferrable, because it's faster. array_shift is used in other situations.
arrshift is more reliable and will always return the first element in the array, but this also modifies the array by removing that element.
arr[0] will fail if your array doesn't start at the 0 index, but leaves the array itself alone.
A more convoluted but reliable method is:
$keys = array_keys($arr);
$first = $arr[$keys[0]];
with array_shif you have two operations:
retrive the firs element
shift the array
if you access by index, actually you have only one operation.
If you want the first element of an array, use $arr[0] form. Advantages - Simplicity, Readability and Maintainability. Keep things straight forward.
Edit: Use index 0 only if you know that the array has default keys starting from 0.
If you don't want to change the array in question, use $arr[0] (which merely gets the first element), otherwise if you want to remove the first element of $arr from $arr, use array_shift($arr).
For example:
$arr=array(3,-6,2);
$foo=$arr[0]; //$foo==3 and $arr==array(3,-6,2).
$bar=array_shift($arr); //$bar==3 and $arr==array(-6,2).
ETA: As others have pointed out, be sure that your array isn't an associative array (ie the keys are 0,1,...,(sizeof($arr)-1)), otherwise this probably won't work.