title: How to averaging over a time period by hours?
body: <p>Im new to R and expirience my first difficulties. I have a data set of ca.10000 obs. of 365 days where I capture occurences of an event. This occurrences are marked out only for the first 14 days of each month. I would like to complement the additional 16 days by averaging over the previous occurrences of the corresponding month(by hour).</p>
  
  <p>The structure is as follows:</p>
  
  <pre><code>                    day           hours      occurrence
                      2000-01-01     1          5
                      2000-01-01     2          6
                      2000-01-01     3          7
                      ...            ...        ...
                      2000-01-01     23         3
                      2000-01-01     24         2
                      ...            ...        ...
                      2000-01-02     1          4
                      2000-01-02     2          2
                      2000-01-02     3          5
                      ...            ...        ...
                      2000-01-02     23         2
                      2000-01-02     24         1
                      ...
                      ...
                      2000-01-15     1          average of the previous 1 hours((5+4+n)/2*k))
                      2000-01-15     2          average of the previous 2 hours ((6+2+n)/2*k))
                      2000-01-15     3          average of the previous 3 hours((7+5+n)/2*k))
                      ...            ...         ...
                      2000-01-15     23         average of the previous 23 hours
                      2000-01-15     24         average of the previous 24 hours
                      ...            ...         ...
                      ...            ...         ...
                      2000-01-30
                      2000-01-30
                      2000-01-30
                      2000-01-30
                      ...            ...         ...
                      ...            ...         ...
                      2000-02-01
                      2000-02-01
                      2000-02-01
                      2000-02-01
                      ...            ...         ...
                      ...
                      ...            ...         ...
                      2000-12-24
  </code></pre>
  
  <p>I tried the </p>
  
  <pre><code>               aggregate( occurences ~ hours, mean) 
  </code></pre>
  
  <p>but the results were pointless and I tried </p>
  
  <pre><code>               tapply( X = occurences, INDEX = list(hours), FUN = Mean )
  </code></pre>
  
  <p>Unfortunately both didnt work as I imagined. I think its necessary to include the corresponding month into the function. However my means seems to be limited.</p>