将对象列表写入CSV文件

Question

将对象列表写入CSV文件

4

我正在编写一个Python程序，循环遍历Reddit的提交内容，提取数据，并将其存储为列表中的对象。然而，我在编写该列表到CSV文件时遇到了问题。文件已创建，但它只给出了一些对象的ID标签。我应该如何更改CSV代码？ 代码：

import praw
from datetime import datetime
import pandas as pd

class Submission:
    def __init__(self, time, score, title, text, ofReddit, serious):
        self.time = time
        self.score = score
        self.title = title
        self.text = text
        self.ofReddit = ofReddit
        self.serious = serious
data = []

reddit = praw.Reddit(client_id=id, client_secret=secret,
                     user_agent='testscript by /u/SilentButtDeadlies')
subreddit = reddit.subreddit('AskReddit')
for submission in subreddit.new(limit=50):
    time = datetime.utcfromtimestamp(submission.created_utc).hour
    score = submission.score
    title = len(submission.title)
    text = len(submission.selftext)
    if 'of reddit' in submission.title.lower():
        ofReddit = 1
    else:
        ofReddit = 0
    if '[serious]' in submission.title.lower():
        serious = 1
    else:
        serious = 0
    data.append(Submission(time, score, title, text, ofReddit, serious))
df = pd.DataFrame(data)
filename = 'AskRedditData' + str(datetime.now()) + '.csv'
df.to_csv(filename, index=False, encoding='utf-8')

CSV文件

0
<__main__.Submission instance at 0x1118f6ef0>
<__main__.Submission instance at 0x1118f68c0>
<__main__.Submission instance at 0x1118f6950>
<__main__.Submission instance at 0x1118c3758>
<__main__.Submission instance at 0x11239c638>
<__main__.Submission instance at 0x11239c5f0>
<__main__.Submission instance at 0x112398908>
<__main__.Submission instance at 0x112398998>
<__main__.Submission instance at 0x112398878>
<__main__.Submission instance at 0x1123989e0>
<__main__.Submission instance at 0x112398c68>
<__main__.Submission instance at 0x11239fe18>
<__main__.Submission instance at 0x11239fe60>
<__main__.Submission instance at 0x11239fea8>
<__main__.Submission instance at 0x11239fef0>
<__main__.Submission instance at 0x11239ff38>
<__main__.Submission instance at 0x11239ff80>
<__main__.Submission instance at 0x11239ffc8>
<__main__.Submission instance at 0x112404050>
<__main__.Submission instance at 0x112404098>
<__main__.Submission instance at 0x1124040e0>
<__main__.Submission instance at 0x112404128>
<__main__.Submission instance at 0x112404170>
<__main__.Submission instance at 0x1124041b8>
<__main__.Submission instance at 0x112404200>
<__main__.Submission instance at 0x112404248>
<__main__.Submission instance at 0x112404290>
<__main__.Submission instance at 0x1124042d8>
<__main__.Submission instance at 0x112404320>
<__main__.Submission instance at 0x112404368>
<__main__.Submission instance at 0x1124043b0>
<__main__.Submission instance at 0x1124043f8>
<__main__.Submission instance at 0x112404440>
<__main__.Submission instance at 0x112404488>
<__main__.Submission instance at 0x1124044d0>
<__main__.Submission instance at 0x112404518>
<__main__.Submission instance at 0x112404560>
<__main__.Submission instance at 0x1124045a8>
<__main__.Submission instance at 0x1124045f0>
<__main__.Submission instance at 0x112404638>
<__main__.Submission instance at 0x112404680>
<__main__.Submission instance at 0x1124046c8>
<__main__.Submission instance at 0x112404710>
<__main__.Submission instance at 0x112404758>
<__main__.Submission instance at 0x1124047a0>
<__main__.Submission instance at 0x1124047e8>
<__main__.Submission instance at 0x112404830>
<__main__.Submission instance at 0x112404878>
<__main__.Submission instance at 0x1124048c0>
<__main__.Submission instance at 0x112404908>

- Marjorie Pickard

你期望它写什么？这是所有对象从“object”继承的默认__str__实现。 - juanpa.arrivillaga

2

另外，你是不是只是用 pandas 来写一个 csv 文件？这似乎有些过度了。你应该使用 csv 模块。 - juanpa.arrivillaga

抱歉，我对这些都很新。只使用CSV文件会更好吗？我希望能够像这样编写对象：{time: ####, score: #### ...} - Marjorie Pickard

尝试将 df = pd.DataFrame(data) 更改为 df = pd.DataFrame([obj.__dict__ for obj in data])。Pandas 数据框需要从 Pandas 可以理解的对象构建，其中一个选项是字典列表。 - calico_

尝试使用我下面使用的答案，包括括号和冒号：@MarjoriePickard。 - juanpa.arrivillaga

1个回答

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- juanpa.arrivillaga · Accepted Answer

您的提交类似乎只是作为记录类型来使用。您可能只需要使用 namedtuple。因此，请将您的类定义替换为：

from collections import namedtuple
Submission = namedtuple('Submission', ['time', 'score', 'title', 'text', 'ofReddit', 'serious'])

现在你的其余代码应该可以正常运行。Pandas不知道如何解释你最初编写的Submission类。因此，它只是创建了一个Submission对象的单列，并在写入时使用默认的str(Submission())，该默认值为object __str__，因为您没有定义另一个__str__。实际上，您想要使用序列。namedtuple函数实际上是一个类工厂，它创建了一个从元组派生的记录类型，因此它具有您需要的所有方便功能和非常方便的构造函数。

现在，由于您正在使用Python 2，我没有修改您使用pandas的方式，即使仅用它来编写csv似乎有点过度。话虽如此，让Python 2 csv模块与Unicode兼容真是一件麻烦事，所以最好保持不变。如果您可以切换到Python 3，则可以将pandas内容简单地替换为：

import csv
with open(filename, 'w', newline='', encoding='utf8') as f:
    writer = csv.writer(f)
    writer.writerow(Submission._fields) # namedtuple breaks convention public fields have single underscore
    writer.writerows(data)