如何对List中的每个Item执行API调用

Question

我试图在元组[(company_name, symbol)]列表中获取每个公司的价格数据。在这个例子中，我使用的是TD Ameritrade API。

同样，我在Reddit上也有同样的问题。唯一的区别是我试图检索每个帖子'id'的所有评论。但是，与Reddit代码我从熊猫df而不是列表拉ID。

这是我现在在哪里:

• 这是TD Ameritrade API

  async def run_app(symbols):
  # empty list to append dataframes to
  all_dfs = []
  for sym,name in symbols:
  # gets the price history data 
  rdata = asyncio.get_price_data(symbol=sym, period='10', periodType='day', frequency='minute', frequencyType='1')
  # prepares data for panda df
  can = unpack_ph_data(rdata, 'candles', 'symbol') 
  # function for creating a panda df
  df = create_ph_df(can) # function for creating a panda df
  # append to all_dfs
  all_dfs.append(df)
  return rdata
  

  我的想法是使用for语句，它将为运行每个步骤符号列表中的每个项目。首先，我尝试没有asyncio，然后我看到一个类似的例子，但没有API，所以我想我会尝试它。

Reddit的

• :

  我正在尝试使用praw包类似的东西。但是对于这个，我从pandas df中的每一行提取数据，并遇到了同样的问题。

  我有一个函数，它获得一个指定的subreddit并返回所有的数据在熊猫df:

  def get_subreddit_data(subreddit="all", limit=25): 
  """
  :param subreddit: Which subreddit to get top posts. 
  :param limit: number of desired posts (This will be for setting the limit 
  after.hot(limit=num_of_posts)and eventually determined from user input. 
  Default 25
  :returns: top posts in subreddit or default (top posts on reddit).
  data is returned in pandas df with the following columns: 
  >>> title, score, id, subreddit, url, comments, selftext, created <<<
  """
  # empty list to insert data to: 
  posts = []
  # variable for data 
  top_posts = reddit.subreddit(subreddit).hot(limit=limit) # limit and subreddit params
  # FOR loop to append data to posts 
  for post in top_posts:
  posts.append([post.title, post.score, post.id, post.subreddit, post.url, post.num_comments, post.selftext, post.created])
  # Create df 
  df = pd.DataFrame(posts, columns=["title","score", "id", "subreddit", "url", "comments","selftext", "created"])
  return df
  

  df = get_reddit_subreddit(subreddit, limit)工作正常，返回熊猫df

  这就是我遇到问题的地方:

  IDs = []
  for ID in [df["id"]]:
  IDs.append(ID) # Add IDs to ID list
  def return_comments_for(ID_list):
  # empty list to append comments to
  _comments = []
  """
  :param ID_list: list of post IDs 
  :returns: list of comments for each post ID 
  in ID_list
  """
  # for loop to extract each ID one by one
  for ID in ID_list:
  # Create submission instance
  submission = reddit.submission(id=ID)
  submission.comments.replace_more(limit=None)
  for comment in submission.comments.list():
  _comments.append(comment.body)
  comments = return_comments_for(IDs)
  

  没有工作，所以我尝试不创建一个函数，并使用队列:

  # Empty list for all IDs
  queue = [] 
  IDs = [df["id"]] # get IDs from DF
  for i in IDs:
  queue.append(i) # Add IDs to queue 
  # list to append comments to
  _comments = []
  while queue:
  # pop item index 0 and assign to ID
  ID = queue.pop(0)
  # create submission instance for ID
  submission = reddit.submission(id=ID)
  submission.comments.replace_more(limit=None)
  # for each comment in submission instance 
  for comment in submission.comments.list():
  _comments.append(comment.body) # append to main comment list
  

  这不是我尝试使用队列堆栈的唯一方法。我试过很多不同的方法，就是记不住。但不管怎样，它们都不起作用，所以我错过了一些东西。

  这是我每次得到的全部错误消息。不管我怎么努力。

  ValueError                                Traceback (most recent call last)
  <ipython-input-9-2cddf98f54ba> in <module>
  20 
  21 
  ---> 22 comments = return_comments_for(IDs)
  23 print(comments)
  <ipython-input-9-2cddf98f54ba> in return_comments_for(ID_list)
  14     for ID in ID_list:
  15         # Create submission instance
  ---> 16         submission = reddit.submission(id=ID)
  17         submission.comments.replace_more(limit=None)
  18         for comment in submission.comments.list():
  C:ProgramDataAnaconda3libsite-packagesprawreddit.py in submission(self, id, url)
  847 
  848         """
  --> 849         return models.Submission(self, id=id, url=url)
  C:ProgramDataAnaconda3libsite-packagesprawmodelsredditsubmission.py in __init__(self, reddit, id, url, _data)
  532 
  533         """
  --> 534         if (id, url, _data).count(None) != 2:
  535             raise TypeError("Exactly one of `id`, `url`, or `_data` must be provided.")
  536         self.comment_limit = 2048
  C:ProgramDataAnaconda3libsite-packagespandascoregeneric.py in __nonzero__(self)
  1476 
  1477     def __nonzero__(self):
  -> 1478         raise ValueError(
  1479             f"The truth value of a {type(self).__name__} is ambiguous. "
  1480             "Use a.empty, a.bool(), a.item(), a.any() or a.all()."
  ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
  

Answer 1

After

IDs = []
for ID in [df["id"]]:
IDs.append(ID) # Add IDs to ID list

IDS是不是int的列表，而是pandas的列表。只包含一个级数，即df["id"]。

# This does what you were trying to do:
IDs = []
for ID in df["id"]:
IDs.append(ID)

# Which can be shortened to
IDs = list(df["id"])
# But I think just passing the Series to your function, should work fine:
comments = return_comments_for(df["id"])

真正的bug是comments在此之后将变成None，因为return_comments_for不返回任何东西，所以它将隐式返回None。

Answer 2

您试图提取id列表的方式是错误的，只需执行以下操作:

IDs = df["id"].values.tolist()