在PHP中使用array_chunk移动元素 [英] Move elements using array_chunk with PHP
问题描述
我有一个基本数组,在其中使用array_chunk将其分为3个元素.
$array = array(
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'
);
$chunk = array_chunk($array, 3);
结果如下
[
[
"a",
"b",
"c"
],
[
"d",
"e",
"f"
],
[
"g",
"h"
]
]
(Las块具有2个元素)
如果最后一个块"只有2个元素,我如何向下移动第一个块的一个元素,以便第一个元素具有2个?
它应该看起来像这样:
[
[
"a",
"b",
],
[
"c"
"d",
"e",
],
[
"f"
"g",
"h
]
]
(第一个块包含2个元素)
最简单的方法是erray_reverse的多重执行:首先反转整个数组,然后拆分,然后反转每个块,最后是块数组.
单线,它看起来像这样:$chunk = array_reverse(array_map('array_reverse', array_chunk(array_reverse($array), 3)));
但是请注意,反转数组是一项昂贵的操作,因此,如果数组比示例中的数组更实际,则不建议这样做.
更有效,但也有更多代码:
使用模计算需要在第一个块中的元素数:
$first_chunk_size = count($array) % 3;
接下来,如果数组大小是块大小的倍数,请避免使用空数组,如果取模为0,请更正块大小:
$first_chunk_size = $first_chunk_size == 0 ? 3 : $first_chunk_size;
然后,切除第一部分:
$first_chunk = array_slice($array, 0, $first_chunk_size);
接下来,拆分数组的其余部分:
$chunks = array_chunk(array_slice($array,$first_chunk_size),3);
然后将第一个块和其他块组合到一个数组中:
array_unshift($chunks, $first_chunk);
第二种方法的完整代码:
$array = [
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'
];
$first_chunk_size = count($array) % 3;
$first_chunk_size = $first_chunk_size == 0 ? 3 : $first_chunk_size;
$first_chunk = array_slice($array, 0, $first_chunk_size);
$chunks = array_chunk(array_slice($array,$first_chunk_size),3);
array_unshift($chunks, $first_chunk);
var_dump($chunks);
(显然,可以通过不一步一步做所有事情来简化此代码)
编辑:在阅读完您对其他答复的评论后,您可以对此方法进行一些修改,然后将其转变为可恢复的功能.进行一些代码清理.它可能看起来像这样:
$array = [
'a', 'b', 'c', 'd', 'e', 'f', 'g'
];
function custom_array_chunk ($array) {
$first_chunk_size = count($array) % 3;
if ($first_chunk_size == 0) {
$chunks = array_chunk($array, 3);
} else {
$chunks = custom_array_chunk(array_slice($array,2));
array_unshift($chunks, array_slice($array, 0, 2));
}
return $chunks;
}
var_dump(custom_array_chunk($array));
这将适用于两种情况,即1个和2个元素剩余",并且将完全产生您告诉我们的内容.
I have a basic array in which I am using array_chunk to divide it into 3 elements.
$array = array(
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'
);
$chunk = array_chunk($array, 3);
The result is as follows
[
[
"a",
"b",
"c"
],
[
"d",
"e",
"f"
],
[
"g",
"h"
]
]
(Las chunk have 2 elements)
In case the last "chunk" has only 2 elements, how can I move down an element of the first chunk so that the first element has 2?
It should look like this:
[
[
"a",
"b",
],
[
"c"
"d",
"e",
],
[
"f"
"g",
"h
]
]
(First chunk have 2 elements)
The easiest way are mutliple executions of erray_reverse: first reverse the entire array, then split, then reverse every chunk and then, lastly, the array of chunks.
As a one-liner, it loooks like this: $chunk = array_reverse(array_map('array_reverse', array_chunk(array_reverse($array), 3)));
Mind however that reversing an array is an expensive operation, so if you array is acutally alrger than in your example, this is not a recommended way.
More effective but also more code:
Calculate the number of elements need to be in the first chunk using modulo:
$first_chunk_size = count($array) % 3;
Next, to avoid an empty array if array size is a multiple of chunk size, correct the chunk size if modulo yields 0:
$first_chunk_size = $first_chunk_size == 0 ? 3 : $first_chunk_size;
then, cut off the first part:
$first_chunk = array_slice($array, 0, $first_chunk_size);
next, split the rest of the array:
$chunks = array_chunk(array_slice($array,$first_chunk_size),3);
then combine the first chunk and the other chunks into one array:
array_unshift($chunks, $first_chunk);
Full code of the second approach:
$array = [
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'
];
$first_chunk_size = count($array) % 3;
$first_chunk_size = $first_chunk_size == 0 ? 3 : $first_chunk_size;
$first_chunk = array_slice($array, 0, $first_chunk_size);
$chunks = array_chunk(array_slice($array,$first_chunk_size),3);
array_unshift($chunks, $first_chunk);
var_dump($chunks);
(obviously this code can be simplified by not doing everything step-by-step)
EDIT: Having read your comments to the other replies, you can modify this approach a little and turn it into a recusrive function. With some code-cleanup,. it may look like this:
$array = [
'a', 'b', 'c', 'd', 'e', 'f', 'g'
];
function custom_array_chunk ($array) {
$first_chunk_size = count($array) % 3;
if ($first_chunk_size == 0) {
$chunks = array_chunk($array, 3);
} else {
$chunks = custom_array_chunk(array_slice($array,2));
array_unshift($chunks, array_slice($array, 0, 2));
}
return $chunks;
}
var_dump(custom_array_chunk($array));
This will work for both cases, 1 and 2 elements "left over" and will yield exactly what you told us.
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