title: in python , i have index but i need to get the index of an element in the dataframe
body: <p>DataFrame df</p>
  <pre><code>    Buy Sell
  0   5.0  NaN
  1   NaN  10.0
  2   NaN  NaN
  3   5.0  NaN
  4   NaN  10.0
  5   18.0 NaN
  6   NaN  30.0
  </code></pre>
  <p>#i need get the index value by providing the cell reference (i.e, df['Buy'][i])</p>
  <pre><code>Buy_index=df['Buy'].values.tolist().index(df['Buy'][0])
  Sell_index=df['Sell'].values.tolist().index(df['Sell'][4])
  print(Buy_index)
  print(Sell_index)
  </code></pre>
  <p>Actual Result:</p>
  <pre><code>0
  1
  </code></pre>
  <p>Expected Result:</p>
  <pre><code>0
  4
  </code></pre>
  <p>Help me</p>