例如我有
[[1,2,3],[1,2,3],3,5,6]
我想把它变成
[1,2,3,1,2,3,3,5,6]
python 3中的代码是什么样的？
答案 0 :(得分：0)
迭代$downloads_model = Printingmachinedownloads::find()->where(['productid'=>$product_id])->orderBy(['type'=>SORT_DESC])->all();
$previous_title = ''; $iteration = 1;
foreach($downloads_model as $doc):
$subtitles = Printingmachinedownloads::find()->where(['productid'=>$product_id, 'type' => $doc['type'] )->all();
$count = count($subtitles);
$previous_title = $previous_title ?: $doc['type'];
if( $previous_title == $doc['type'] && $count == $iteration ):
<div class="amazingcarousel-container-1 tab_style">
<h3><?= $previous_title ?></h3>
foreach($subtitles as $subtitle):
<a target = '_blank' href="<?php echo Yii::$app->homeUrl?>images/printingmachine/downloads/<?php echo $subtitle['documentname']; ?>">
<?php echo $subtitle['documentlabel'] ?>
</a>
enforeach;
</div>
$previous_title = ''; $iteration = 1;
else:
$iteration++;
endif;
endforeach;
个项目，如果项目是列表则迭代子项目;其他只是附加到新列表：
a使用list comprehension（嵌套a = [[1,2,3],[1,2,3],3,5,6]
b = []
for x in a:
if isinstance(x, list):
b.extend(x)
else:
b.append(x)
# b == [1,2,3,1,2,3,3,5,6]
）与conditional expression相结合的另一种方法：
for