[R] Counting with multiple criteria using data table

[Bert Gunter]

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Bert


Bert Gunter

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On Wed, Jun 21, 2017 at 2:50 PM, Ek Esawi <esawiek at gmail.com> wrote:
> I have a data.table which is shown below. I want to count combinations of
> columns on i and count on j with by. A few examples are given below the
> table.
>
>
>
> I want to:
>
> all months to show on the output including those that they have zero value
>
> I want the three statements combined in on if possible so the output will
> be one data table; that is the outputs are next to each other as manually
> illustrated on the last part (desired output).
>
>
>
>
>
> Thanks--EK
>
>
>
>
>
>> Test
>
>      Color Grade Value  Month Day
>
>  1: yellow     A    20    May   1
>
>  2:  green     B    25   June   2
>
>  3:  green     A    10  April   3
>
>  4:  black     A    17 August   3
>
>  5:    red     C     5    May   5
>
>  6: orange     D     0   June  13
>
>  7: orange     E    12  April   5
>
>  8: orange     F    11 August   8
>
>  9: orange     F    99  April  23
>
> 10: orange     F    70    May   7
>
> 11:  black     A    77   June  11
>
> 12:  green     B    87 August  33
>
> 13:  black     A    79  April   9
>
> 14:  green     A    68    May  14
>
> 15:  black     C    90   June  31
>
> 16:  green     D    79 August  11
>
> 17:  black     E   101  April  17
>
> 18:    red     F    90   June  21
>
> 19:    red     F   112 August  13
>
> 20:    red     F   101  April  20
>
>> Test[Color=="green"&Grade=="A", .N, by=Month]
>
>    Month N
>
> 1: April 1
>
> 2:   May 1
>
>> Test[Color=="orange"&Grade=="F", .N, by=Month]
>
>     Month N
>
> 1: August 1
>
> 2:  April 1
>
> 3:    May 1
>
>
>
>> Test[Color=="orange"&Grade=="F", .N, by=Month]
>
>     Month     N
>
> 1: August     1
>
> 2:  April     1
>
> 3:    May     1
>
>> Test[Color=="red"&Grade=="F", .N, by=Month]
>
>     Month N
>
> 1:   June 1
>
> 2: August 1
>
> 3:  April 1
>
>
>
> Desired output
>
>                 N1           N2           N3
>
> April       1              1              1
>
> May       1              1              1
>
> June        0              0              0
>
> August 0                1              1
>
>         [[alternative HTML version deleted]]
>
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