Question

假设我有以下元组列表：

[('test', {'key': 'testval1' }),
 ('test', {'key': 'testval2' }),
 ('test', {'key': 'testval3' }),
 ('test', {'key': 'testval4' }),
 ('foo', {'key': 'testval5' }),
 ('oof', {'key': 'testval6' }),
 ('qux', {'key': 'testval7' }),
 ('qux', {'key': 'testval8' })]

我想过滤并获取具有第一项“ test”字符串的第二项对象的所有值的列表。所以输出将是：

['testval1','testval2','testval3','testval4']

设法通过Output = list（filter（lambda x：'test'in x，condition））获得测试元素。但这又给了我另一个元组列表。我如何才能再次获得没有循环的第二个obj元素的值？

Answer 1

>>> elements = [('test', {'key': 'testval1' }),
...  ('test', {'key': 'testval2' }),
...  ('test', {'key': 'testval3' }),
...  ('test', {'key': 'testval4' }),
...  ('foo', {'key': 'testval5' }),
...  ('oof', {'key': 'testval6' }),
...  ('qux', {'key': 'testval7' }),
...  ('qux', {'key': 'testval8' })]
>>> [d['key'] for (s, d) in elements if s == 'test']
['testval1', 'testval2', 'testval3', 'testval4']

Answer 2

使用单个理解即可做到：

[b['key'] for a, b in data if a == 'test']

（假设您的列表为data）

Answer 3

你可以做

print([*map(lambda x: x[1]['key'], filter(lambda x: x[0] == 'test' in x, a))])

列表理解是通过在列表名称后添加if来过滤此类列表的好方法。
或者您可以通过过滤器和地图来完成

print(list(map(lambda x: x[1]['key'], filter(lambda x: x[0] == 'test' in x, a))))

或

['testval1', 'testval2', 'testval3', 'testval4']

所有这些都将输出

function wmtp_gallery_block_static_function () {
    global $wpdb;
    $domain = 'wmtp-gallery-js';
    $table_name = $wpdb->prefix . 'wmtp_gallery_block_static';


    if(isset($_POST['submit'])){

        if ( ! function_exists( 'wp_handle_upload' ) ) {
                require_once( ABSPATH . 'wp-admin/includes/file.php' );
            }
        $file = count($_FILES['upload']['name']);
        $upload_dir=wp_upload_dir();
        $url=$upload_dir['url'].'/'.$file;

        $uploadedfile = $_FILES['upload'];
        $upload_overrides = array( 'test_form' => false );

        $movefile = wp_handle_upload( $uploadedfile, $upload_overrides );

        $post_data=array(
            'images' => esc_url($movefile["url"])
        );
        $post_format=array(
            '%s'
        );
        $wpdb->insert( $table_name, $post_data, $post_format);
    } 
    ?>
    <h1>Upload The Image</h1>

    <form action="" method="POST" enctype="multipart/form-data">
      <label for="files">Select files:</label>
      <input type="file" id="files" name="upload[]" multiple><br><br>
      <input type="submit" name="submit">
    </form>

    <h2>All Images Are Available</h2>
    <?php   
    $data = $wpdb->get_results($wpdb->prepare( "SELECT * FROM $table_name" ));
    echo '<div class="wmtp-galeery-admin">';
    foreach ($data as $img) {
        if(isset($img->images)) {
            echo '<img src="'.$img->images.'">';
        } else {
            echo '';
        }
    }
    echo '</div>';
}

Answer 4

使用Setdefault

output=[]

for item,dict in  li:
   if item == 'test':
       var = dict.setdefault('key',{})
       output.append(var)

print(output)

根据第一个元素搜索元组列表并获取第二个元素值列表

4 个答案: