php 去重累加的例子

本文章为各位介绍关于php 去重累加的例子,希望这篇文章能够让各位了解到关于php 去重累加方法哦,希望文章对各位有帮助.

   
    /**
     * 数据去重累加
     *
     * @param $array
     * @param string $reference_str  参照str
     * @param string $accumulation_str  累加str
     * @return mixed
     */
    public function arrayHeavyAccumulation($array , $reference_str, $accumulation_str)
    {
        $unset = array();

        for ($i = 0; $i < count($array); $i++){
            for ($j = $i+1; $j  $value){
            unset($array[$value]);
        }

        return array_merge($array);
    }

PHP去重我们如果数据量小肯定不会考虑到优化了,但是如果碰到量大的话那就必须得用到最好的算法了,今天我们来看关于PHP去重进行算法升级过程吧.

最近公司在做一个项目，需要对爬取到的数据进行去重，方法就是根据数据的id，去除掉id重复的数据。

下面是这个方法的演化过程。

// 去重
$arr_id = array();
$LeTVFeedList = array();
for ($i = 0; $i < count($arrFeedList); $i++){
    if(!in_array($arrFeedList[i]['id'], $arr_id)){
        $LeTVFeedList[] = $arrFeedList[i];
        $arr_id[] = $arrFeedList[i]['id'];
    }
}

从上面的算法中可以看到，上面的算法用了两个数组，两个循环，所以它的时间复杂度为O(n^2)，空间复杂度为O(2n)。上面的算法，我们可以从in_array()入手，考虑下面的因素。

用数组的id作数组下标，来存储爬取到的数据值。

// 去重
$tmp_arr = array();
for ($i = 0; $i < min(count($arrFeedList),10); $i++){
    $tmp_arr[$arrFeedList[$i]['id']] = $arrFeedList[$i];
}
$arrLeTVFeedList = array();
foreach ($tmp_arr as $key => $value){
    $arrLeTVFeedList[] = $value;
}

这里用了两个循环，两个数组，时间复杂度是O(2n),空间复杂度是O(2n).

后来又对循环进行了优化，变成如下代码：

// 去重
$tmp_arr = array();
$arrLeTVFeedList = array();
foreach ($arrFeedList as $key => $value){
    if(!isset($tmp_arr[$key['id']])){
        $tmp_arr[$key['id']] = $value;
        $arrLeTVFeedList[] = $value;
    }
}

isset是速度要快于for循环，以上代码是最终版本

下面我们来看一篇关于php将数组转换成字符串例子,这篇文章希望能够给各位带来帮助,具体的细节如下文所示.

1.implode将数组元素组合为字符串

连接符为 ^ 的例子：

<?php
$array = array('姓名', '电话', '电子邮箱');
$char = implode("^", $array);
echo $char;
?>
浏览器输出：
姓名^电话^电子邮箱
可以使用空格作为连接符：
<?php
$char = implode(" ", $array);
?>

2.自定义函数

function array2string($data, $isformdata = 1) {
    if($data == '') return '';
    //if($isformdata) $data = stripslashes($data);
    return addslashes(var_export($data, TRUE));
}

字符转换成数组

例子 1. explode() 示例

 
<?php
// 示例 1
$pizza = "piece1 piece2 piece3 piece4 piece5 piece6";
$pieces = explode(" ", $pizza);
echo $pieces[0]; // piece1
echo $pieces[1]; // piece2
// 示例 2
$data = "foo:*:1023:1000::/home/foo:/bin/sh";
list($user, $pass, $uid, $gid, $gecos, $home, $shell) = explode(":", $data);
echo $user; // foo
echo $pass; // *
?>

例子 2. limit 参数示例

 
<?php
$str = 'one|two|three|four';
// 正数的 limit
print_r(explode('|', $str, 2));
// 负数的 limit
print_r(explode('|', $str, -1));
?>

以上示例将输出：
Array
(
[0] => one
[1] => two|three|four
)
Array
(
[0] => one
[1] => two
[2] => three
)

文章进行分页需要进行判断了,当然也有在数据库中存储几条记录了我们这里介绍的是关于长文章进行分页的代码哦.

require "page.class.php";
$neirong = "内容内容内容内容内容内容内容内容内容内容内容内容内容内容";
$content = file_get_contents($neirong);
$ipage = isset($_GET["ipage"]) ? intval($_GET["ipage"]) : 1;
$CP = new cutpage($content);
$page = $CP->cut_str();
echo $page[$ipage - 1];
echo '' . $CP->pagenav() . '';

class类

page.class.php

<?php   
/* 
*  长文章分页类    
*/ 
    class cutpage{   
        private $pagestr;       //被切分的内容   
        private $pagearr;       //被切分文字的数组格式   
        private $sum_word;      //总字数(UTF-8格式的中文字符也包括)   
        private $sum_page;      //总页数   
        private $page_word;     //一页多少字   
        private $cut_tag;       //自动分页符   
        private $cut_custom;    //手动分页符   
        private $ipage;         //当前切分的页数，第几页   
        private $url;   
        
        function __construct($pagestr,$page_word=1000){   
            $this->page_word = $page_word;   
            $this->cut_tag = array("</table>", "</div>", "</p>", "<br/>", "”。", "。", ".", "！", "……", "？", ",");   
            $this->cut_custom = "{nextpage}";   
            $tmp_page = isset($_GET["ipage"]) ? intval($_GET["ipage"]) : 1;   
            $this->ipage = $tmp_page>1?$tmp_page:1;
            $this->pagestr = $pagestr;
        }   
        //统计总字数   
        function get_page_word(){   
            $this->sum_word = $this->strlen_utf8($this->pagestr);   
            return $this->sum_word;   
        }   
        /*  统计UTF-8编码的字符长度 
         *  一个中文，一个英文都为一个字 
         */ 
        function strlen_utf8($str){   
           $i = 0;   
           $count = 0;   
           $len = strlen ($str);   
           while ($i < $len){   
               $chr = ord ($str[$i]);   
               $count++;   
               $i++;   
               if ($i >= $len)   
                   break;   
               if ($chr & 0x80){   
                   $chr <<= 1;   
                   while ($chr & 0x80) {   
                       $i++;   
                       $chr <<= 1;   
                   }   
               }   
           }   
           return $count;   
        }   
        //设置自动分页符号   
        function set_cut_tag($tag_arr=array()){   
            $this->cut_tag = $tag_arr;   
        }   
        //设置手动分页符   
        function set_cut_custom($cut_str){   
            $this->cut_custom = $cut_str;   
        }   
        function show_cpage($ipage=0){   
            $this->cut_str();   
            $ipage = $ipage ? $ipage:$this->ipage;   
            return $this->pagearr[$ipage];   
        }   
        function cut_str(){   
            $str_len_word = strlen($this->pagestr);     //获取使用strlen得到的字符总数   
            $i = 0;   
            if ($str_len_word<=$this->page_word){   //如果总字数小于一页显示字数   
                $page_arr[$i] = $this->pagestr;   
            }else{   
                if (strpos($this->pagestr, $this->cut_custom)){   
                    $page_arr = explode($this->cut_custom, $this->pagestr);   
                }else{   
                    $str_first = substr($this->pagestr, 0, $this->page_word);   //0-page_word个文字    cutStr为func.global中的函数   
                    foreach ($this->cut_tag as $v){   
                        $cut_start = strrpos($str_first, $v);       //逆向查找第一个分页符的位置   
                        if ($cut_start){   
                            $page_arr[$i++] = substr($this->pagestr, 0, $cut_start).$v;   
                            $cut_start = $cut_start + strlen($v);   
                            break;   
                        }   
                    }   
                    if (($cut_start+$this->page_word)>=$str_len_word){  //如果超过总字数   
                        $page_arr[$i++] = substr($this->pagestr, $cut_start, $this->page_word);   
                    }else{   
                        while (($cut_start+$this->page_word)<$str_len_word){   
                            foreach ($this->cut_tag as $v){   
                                $str_tmp = substr($this->pagestr, $cut_start, $this->page_word);        //取第cut_start个字后的page_word个字符   
                                $cut_tmp = strrpos($str_tmp, $v);       //找出从第cut_start个字之后，page_word个字之间，逆向查找第一个分页符的位置   
                                if ($cut_tmp){   
                                    $page_arr[$i++] = substr($str_tmp, 0, $cut_tmp).$v;   
                                    $cut_start = $cut_start + $cut_tmp + strlen($v);   
                                    break;   
                                }   
                            }     
                        }   
                        if (($cut_start+$this->page_word)>$str_len_word){   
                            $page_arr[$i++] = substr($this->pagestr, $cut_start, $this->page_word);   
                        }   
                    }   
                }   
            }   
            $this->sum_page = count($page_arr);     //总页数   
            $this->pagearr = $page_arr; 
            return $page_arr;
        }   
        //显示上一条，下一条   
        function pagenav(){   
            $this->set_url();   
            $str = '';
            
            //$str .= $this->ipage.'/'.$this->sum_page;
            
            for($i=1;$i<=$this->sum_page;$i++){
                if($i==$this->ipage) {
                    $str.= "<a href='#' class='cur'>".$i."</a> ";
                }else{
                    $str.= "<a href='".$this->url.$i."'>".$i."</a> ";
                }
            }
            
                 
            return $str;   
        }   
        function show_prv_next2(){   
            $this->set_url();   
            $str = '';
            
            
            
            if ($this->sum_page>1 and $this->ipage>1){   
                $str.= "<a href='".$this->url.($this->ipage-1)."'>上一页</a> ";   
            }  
            if ($this->sum_page>1 and $this->ipage<$this->sum_page){   
                $str .= "<a href='".$this->url.($this->ipage+1)."'>下一页</a>";   
            }          
            return $str;   
        }   
        function show_page_select(){   
            if ($this->sum_page>1){   
                $str = "   <select onchange='location.href=this.options[this.selectedIndex].value'>";   
                for ($i=1; $i<=$this->sum_page; $i++){   
                    $str.= "<option value='".$this->url.$i."' ".(($this->ipage)==$i ? " selected='selected'":"").">第".$i."页</option>";   
                }   
                $str.= "</select>";   
            }   
            return $str;   
        }   
        function show_page_select_wap(){   
            if ($this->sum_page>1){   
                $str = "<select ivalue='".($this->ipage-1)."'>";   
                for ($i=1; $i<=$this->sum_page; $i++){   
                    $str.= "<option onpick='".$this->url.$i."'>第".$i."节</option>";   
                }   
                $str.= "</select>";   
            }   
            return $str;   
        }   
        function set_url(){   
            parse_str($_SERVER["QUERY_STRING"], $arr_url);   
            unset($arr_url["ipage"]);   
            if (empty($arr_url)){   
                $str = "ipage=";   
            }else{   
                $str = http_build_query($arr_url)."&ipage=";   
            }   
            $this->url = "http://".$_SERVER["HTTP_HOST"].$_SERVER["PHP_SELF"]."?".$str;   
        }   
    }   
?>

下面我们来看一篇关于Drupal db_select addExpression表达式的用法吧,希望这篇文章能够帮助到各位朋友,具体如下.

$query = db_select('turnover_estimate', 'e');
$query->fields('e');
$query->addExpression("DATE_FORMAT(date, '%Y-%m-%d')", 'date_format');
$res =  $query->execute()->fetchAllAssoc('date_format');

如上代码可以正确执行。但是略有小坑。

$query->addExpression('DATE_FORMAT(date, "%Y-%m-%d"), 'date_format');

注意单引号和双引号，这里的写法会报错。