I have data that I work with, which is count data i.e. every date+time combination represents a data point. So my current data frame looks as follows:

```
  DATE        TIME
1 2014-02-15  15:02
2 2014-02-15  15:12
3 2014-04-15  02:02
4 2014-05-15  11:02
5 2014-06-15  15:42
6 2014-06-15  16:02
....

```

Now I want to have a new DF that counts how many data points there are per hour for a particular date. Something like below:

```
  DATE        HOUR    COUNT
1 2014-02-15  15      2
2 2014-04-15  02      1
3 2014-05-15  11      1
4 2014-06-15  15      1
5 2014-06-15  16      1
....

```

I want to do this so that I can make a boxplot with x = hour of the day, y = number of data points (over a year). Tried to do it with nested for loops, but it didn't work.

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EDIT: and if possible, the date/hour combination where there is no data point should be in the data frame, but with COUNT = 0.