title: Convert time to fraction of a day, fraction of a week and fraction of a month in R
body: <p>I have this dataset with times:</p>
  <pre><code>id    time
  1     4/01/2019 08:00:00
  2     4/02/2019 12:00:00
  3     4/03/2019 18:00:00
  </code></pre>
  <p>And I want the fraction of a day, fraction of the week and fraction of the month. For example for the first row 08:00:00 is one third of a day, so first column should be 0.333. And it was Monday so it should be 0.047 (a complete day is 1/7 = 0.143 of a week, but since it's a third then 0.143 * 0.333 = 0.047). And it was the start of the month so it should be 0.011 (a complete day is 1/30 = 0.033 of a month, but it is only 8:am so it is 0.033 * 0.333 = 0.011.</p>
  <p>The expected result should be:</p>
  <pre><code>id    time                 frac_day    frac_week    frac_month
  1     4/01/2019 08:00:00   0.333       0.047        0.011
  2     4/02/2019 12:00:00   0.5         0.214        0.050
  3     4/03/2019 18:00:00   0.75        0.393        0.092    
  </code></pre>
  <p>Please, could you help me with this question? Any help will be greatly appreciated.</p>