title: Add a column to a dataframe in Python
body: <p>I am trying to add a few columns to a dataframe - here is the code</p>
  <pre class="lang-py prettyprint-override"><code>import import_ipynb
  import talib
  import numpy
  import yfinance as yf
  import datetime as dt
  import time
  from datetime import datetime, timedelta 
  import sqlite3
  import pandas
  import numpy as np
  conn = sqlite3.connect('Strategy_RSI_MACD_Data.db')
  c = conn.cursor()
   
  c.execute(&quot;select distinct Stock from Universe&quot;)
  tickers = c.fetchall()   
  for row in tickers:
      if row[0]:
          ticker_list.append(row[0])
          stockdetails = yf.download(
              tickers = ticker_list,
              period = '6mo',
              interval = '1d',
              group_by = 'ticker',
              auto_adjust = False,
              prepost = False,
              threads = True,
              proxy = None
          )
  
  df_ta = pandas.DataFrame(data = stockdetails['Adj Close'], dtype=numpy.float64)
  stockdetails['RSI'] = df_ta.apply(lambda c: talib.RSI(c, timeperiod = 14))
  </code></pre>
  <p>The last line is throwing this error:</p>
  <blockquote>
  <p>ValueError: Wrong number of items passed 505, placement implies 1</p>
  </blockquote>
  <p>How can I fix this?</p>