title: Is there a standard name for the groupby/apply operation?
body: <h1>Data</h1>
  <p>CategoricalVariable CV1 : X1,X2,X3...Xn</p>
  <p>NumericalVariable   NV1 : 1-1000</p>
  <p>Time                    : 0-100</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>C1</th>
  <th>Time</th>
  <th>NV1</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>X1</td>
  <td>0</td>
  <td>1</td>
  </tr>
  <tr>
  <td>X1</td>
  <td>1</td>
  <td>100</td>
  </tr>
  <tr>
  <td>X2</td>
  <td>0</td>
  <td>200</td>
  </tr>
  <tr>
  <td>X2</td>
  <td>1</td>
  <td>500</td>
  </tr>
  </tbody>
  </table>
  </div><h1>Operation 1: Split by Categorical Variable</h1>
  <h2>DataFrame1</h2>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>C1</th>
  <th>Time</th>
  <th>NV1</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>X1</td>
  <td>0</td>
  <td>1</td>
  </tr>
  <tr>
  <td>X1</td>
  <td>1</td>
  <td>100</td>
  </tr>
  </tbody>
  </table>
  </div><h2>DataFrame2</h2>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>C1</th>
  <th>Time</th>
  <th>NV1</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>X2</td>
  <td>0</td>
  <td>200</td>
  </tr>
  <tr>
  <td>X2</td>
  <td>1</td>
  <td>500</td>
  </tr>
  </tbody>
  </table>
  </div><h1>Operation 2: Apply Custom Function</h1>
  <pre><code>import numpy as np 
  
  def custom_func (anyarray):
      last_element_in_array = anyarray [-1] 
      first_element_in_array = anyarray [0] 
      return  np.sin (last_element_in_array) * np.ln (first_element_in_array)
       
  custom_func (DataFrame1 ['NV1'].values) # np.sin (100) * np.ln (1)
  
  </code></pre>
  <h1>Operation 3: Re-Combine DataFrame1 and DataFrame2</h1>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>C1</th>
  <th>NV1</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>X2</td>
  <td>Custom Function output : np.sin (100) * np.ln (1)</td>
  </tr>
  <tr>
  <td>X2</td>
  <td>Custom Function output : np.sin (500) * np.ln (200)</td>
  </tr>
  </tbody>
  </table>
  </div>