title: How to fill the "missing time pattern" and "fill them" with particular value efficiently with python?
body: <p>I'd like to "extend" my row from:</p>
  
  <pre><code>+-------------+---------+-------+-------+
  | Week Number | Weekday | Time  | Speed |
  +-------------+---------+-------+-------+
  |           1 | Monday  | 09.00 |     2 |
  |           1 | Monday  | 12.00 |     2 |
  |           1 | Monday  | 14.00 |     2 |
  |           1 | Monday  | 15.00 |     1 |
  |           1 | Tuesday | 08.00 |     4 |
  |           1 | Tuesday | 10.00 |     2 |
  |           1 | Tuesday | 11.00 |     3 |
  |           1 | Tuesday | 13.00 |     2 |
  +-------------+---------+-------+-------+
  </code></pre>
  
  <p>into the following pattern for each day: 
  08.00, 09.00, 10.00, 11.00, 12.00, 13.00, 14.00, 15.00</p>
  
  <pre><code>+-------------+---------+-------+-------+
  | Week Number | Weekday | Time  | Speed |
  +-------------+---------+-------+-------+
  |           1 | Monday  | 08.00 |     0 |
  |           1 | Monday  | 09.00 |     2 |
  |           1 | Monday  | 10.00 |     0 |
  |           1 | Monday  | 11.00 |     0 |
  |           1 | Monday  | 12.00 |     2 |
  |           1 | Monday  | 13.00 |     0 |
  |           1 | Monday  | 14.00 |     2 |
  |           1 | Monday  | 15.00 |     1 |
  |           1 | Tuesday | 08.00 |     4 |
  |           1 | Tuesday | 09.00 |     0 |
  |           1 | Tuesday | 10.00 |     2 |
  |           1 | Tuesday | 11.00 |     3 |
  |           1 | Tuesday | 12.00 |     0 |
  |           1 | Tuesday | 13.00 |     3 |
  |           1 | Tuesday | 14.00 |     0 |
  |           1 | Tuesday | 15.00 |     0 |
  +-------------+---------+-------+-------+
  </code></pre>
  
  <p>and fill the "missing" with 0.
  How can I suppose to do?</p>
  
  <p>I'm using python 3.6 with pandas library.</p>