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Asked:2020-08-10 14:36:53 +0000 UTC2020-08-10 14:36:53 +0000 UTC

如何在python中将多个条件合并为一个？

  • 772

我使用 Vk API 并希望简化代码。因为我可以有10个这样的条件，但我不想用这个填写所有的代码。有没有办法减少？

这是代码：

def safe_file(posts):
    with open('test.csv', 'w', newline='', encoding='utf-8') as file:
        title = csv.writer(file, delimiter=';')
        title. writerow(['text', 'image', 'url'])
        for post in posts:
            try:
                if post ['id']:
                    i = post ['id']
                else:
                    i = 'pass'
                if post ['text']:
                    text = post ['text']
                else:
                    text = 'pass'
                if post ['attachments'][0]['photo']['sizes'][-1]['url']:
                    img = post ['attachments'][0]['photo']['sizes'][-1]['url']
                else:
                    img = 'pass'
            except:
                pass
                img = 'pass'

            title.writerow((text, i, img))

我需要简化这部分代码：

for post in posts:
            try:
                if post ['id']:
                    i = post ['id']
                else:
                    i = 'pass'
                if post ['text']:
                    text = post ['text']
                else:
                    text = 'pass'
                if post ['attachments'][0]['photo']['sizes'][-1]['url']:
                    img = post ['attachments'][0]['photo']['sizes'][-1]['url']
                else:
                    img = 'pass'
            except:
                pass
                img = 'pass'
python

3 个回答

  1. 我会建议一个默认选项，所以让我们称之为

    def try_extract_image_url(post):
    try:
        return post['attachments'][0]['photo']['sizes'][-1]['url']
    except (KeyError, IndexError) as e:
        return None

for post in posts:
    id = post['id'] or 'pass'
    text = post['text'] or 'pass'
    img = try_extract_image_url(post) or 'pass'

    您仍然可以解决此问题并提出更好的建议，例如，将“通过”替换为更具体的内容，以便更容易在代码中进一步过滤和处理它。例如，为此创建一个特殊对象。

    • 5
  2. Best Answer

    对于初学者，您可以使用条件运算符

    if post ['id']:
    i = post ['id']
else:
    i = 'pass'

    使用条件表达式写得更短：

    i = post['id'] if post['id'] else 'pass'

    之后，我将创建一个执行所有三个任务的函数：

    def con_ass(post):
    i = post['id'] if post['id'] else 'pass'
    text = ...
    img = ...
    reurn i,text,img

    在程序中，这些分配看起来像这样：

    i,text,img = con_ass(post)

    在我看来 - 非常紧凑和可见。

    • 2

  3. 更正的代码：

    for post in posts:
            try:
                if post ['id']:
                    i = post ['id']
                elif: post ['text']:
                    text = post ['text']
                elif: post ['attachments'][0]['photo']['sizes'][-1]['url']:
                    img = post ['attachments'][0]['photo']['sizes'][-1]['url']
                else:
                    img = 'pass'
            except:
                pass
                img = 'pass'
    • 0

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