Except Exception error handling in Python is not working

Question

I am trying to scrape stock market information from all the stocks concerning the FTSE250. I use Yahoo_Fin in order to do so. The code works, but I get an error that a stock is delisted. Hence, I tried to put-in an except exception code. I read the documentation about the try and except libraries, but could not find the correct answer. I don't receive a syntax error, but the except exception code doesn't do anything.

EDIT: Putting two except exceptions works, below is the updated code.

index_df = pdr.get_data_yahoo(index_name, start_date, end_date, progress=False)
index_df['Percent Change'] = index_df['Adj Close'].pct_change()
index_return = (index_df['Percent Change'] + 1).cumprod()[-1]

for ticker in tickers:
    # Download historical data as CSV for each stock (makes the process faster)
  try:
      df = pdr.get_data_yahoo(ticker, start_date, end_date,progress=False)
      df.to_csv(f'{ticker}.csv')
  except: 
    except Exception: 
    if ticker not in tickers:
    next(ticker)

for ticker in tickers:
  try:

   # Calculating returns relative to the market (returns multiple)
    df['Percent Change'] = df['Adj Close'].pct_change()
    stock_return = (df['Percent Change'] + 1).cumprod()[-1]
    
    returns_multiple = round((stock_return / index_return), 2)
    returns_multiples.extend([returns_multiple])

  except Exception: 
   if ticker not in tickers:
    next(ticker)

1 Failed download: - 3IN: No data found, symbol may be delisted and IndexError: index -1 is out of bounds for axis 0 with size 0 — JD_BNL
– JD_BNL, Commented Mar 29, 2021 at 19:11

Ed OBrien · Accepted Answer · 2021-03-31 19:18:31Z

1

Your exception doesn't make sense to me. You are looping over the tickers, then you check if the ticker is not in tickers. That will always be False, so your "next" statement is never going to be executed and it will just continue on.

Seems what you want is something like this:

for ticker in tickers:
    # Download historical data as CSV for each stock (makes the process faster)
    try:
        df = pdr.get_data_yahoo(ticker, start_date, end_date,progress=False)
        df.to_csv(f'{ticker}.csv')

        # Calculating returns relative to the market (returns multiple)
        df['Percent Change'] = df['Adj Close'].pct_change()
        stock_return = (df['Percent Change'] + 1).cumprod()[-1]

        returns_multiple = round((stock_return / index_return), 2)
        returns_multiples.extend([returns_multiple])

        #change the name of the stock index
        print (f'Ticker: {ticker};  Returns Multiple against FTSE 250 : {returns_multiple}\n')
        time.sleep(1)
 
    except IndexError:
        print(f"Error in ticker: {ticker}, skipping...")

Where you pass a proper except condition depending on what the traceback is (can't tell if it's FileNotFoundError or IndexError). But I think all you want to do is process the next ticker in the list?

edited Mar 31, 2021 at 19:18

answered Mar 29, 2021 at 20:10

Ed OBrien

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4 Comments

JD_BNL Over a year ago

I want to stop process if a ticker is not fond and continue with the next ticker. The code stops at stock_return = (df['Percent Change'] + 1).cumprod()[-1]. So to code can't calculate the returns of the stock relative to the market. The except: continue code does't help as well.

Ed OBrien Over a year ago

Probably best practice would be to put your entire code in the try block with an exception (you still haven't posted the actual Traceback) to catch whatever is causing the error. It sounds like you are saying the except block is before where the actual error occurs. I suggested continue because that should grab the next ticker in the list and try to process it instead.

Ed OBrien Over a year ago

Note that you might be running into two possible error conditions - one where the ticker isn't found and another where it's found but the data is missing. So you might need two exceptions if that is the case.

JD_BNL Over a year ago

thank you, creating two exceptions works.

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