Re: How can I totalize by month, by year?

• To: mathgroup at smc.vnet.net
• Subject: [mg111909] Re: How can I totalize by month, by year?
• From: Ray Koopman <koopman at sfu.ca>
• Date: Wed, 18 Aug 2010 07:06:41 -0400 (EDT)
• References: <201006301204.IAA27569@smc.vnet.net> <i4d6av\$6r3\$1@smc.vnet.net>

```On Aug 16, 10:22 pm, "Leandro Tenfen" <leandroten... at hotmail.com>
wrote:
> Hi,
>
> I'm new with Mathematica, I need some help to start it.
>
> I've got a date series like a cashflow, how can I totalize at each date
> change? And how can I totalize by month, by year, etc?
>
> For example:
>
> In[]=
>
> {{{{2010, 8, 3, 0, 0, 0.},
>    65.}, {{2010, 8, 3, 0, 0, 0.}, -72.}, {{2010, 8, 3, 0, 0, 0.},
>    45.}, {{2010, 8, 2, 0, 0, 0.}, 67.}, {{2010, 8, 2, 0, 0, 0.},
>    83.}, {{2010, 8, 2, 0, 0, 0.}, -42.}, {{2010, 7, 30, 0, 0,
>     0.}, -32.}, {{2010, 7, 30, 0, 0, 0.},
>    48.}, {{2010, 7, 30, 0, 0, 0.}, 12.}, {{2010, 7, 30, 0, 0, 0.},
>    34.}, {{2010, 7, 29, 0, 0, 0.}, -52.}, {{2010, 7, 29, 0, 0, 0.},
>    78.}, {{2010, 7, 29, 0, 0, 0.}, -26.}, {{2010, 7, 28, 0, 0, 0.},
>    45.}, {{2010, 7, 28, 0, 0, 0.}, -23.}, {{2010, 7, 28, 0, 0,
>     0.}, -32.}, {{2010, 7, 28, 0, 0, 0.},
>    74.}, {{2010, 7, 27, 0, 0, 0.}, 53.}, {{2010, 7, 27, 0, 0, 0.},
>    58.}, {{2010, 7, 27, 0, 0, 0.}, 25.}}}
>
> Out[]=
>
> {{{{2010, 8, 3, 0, 0, 0.}, 38.}, {{2010, 8, 2, 0, 0, 0.},
>    108.}, {{2010, 7, 30, 0, 0, 0.},
>    28.}, {{2010, 7, 29, 0, 0, 0.}, -10.}, {{2010, 7, 28, 0, 0, 0.},
>    64.}, {{2010, 7, 2, 0, 0, 0.}, 136.}}}
>
> Thanks
> Leandro Tenfen

data = Flatten[ (* eliminate the outer level *)
{{{{2010, 8,  3, 0, 0, 0.},  65.},
{{2010, 8,  3, 0, 0, 0.}, -72.},
{{2010, 8,  3, 0, 0, 0.},  45.},
{{2010, 8,  2, 0, 0, 0.},  67.},
{{2010, 8,  2, 0, 0, 0.},  83.},
{{2010, 8,  2, 0, 0, 0.}, -42.},
{{2010, 7, 30, 0, 0, 0.}, -32.},
{{2010, 7, 30, 0, 0, 0.},  48.},
{{2010, 7, 30, 0, 0, 0.},  12.},
{{2010, 7, 30, 0, 0, 0.},  34.},
{{2010, 7, 29, 0, 0, 0.}, -52.},
{{2010, 7, 29, 0, 0, 0.},  78.},
{{2010, 7, 29, 0, 0, 0.}, -26.},
{{2010, 7, 28, 0, 0, 0.},  45.},
{{2010, 7, 28, 0, 0, 0.}, -23.},
{{2010, 7, 28, 0, 0, 0.}, -32.},
{{2010, 7, 28, 0, 0, 0.},  74.},
{{2010, 7, 27, 0, 0, 0.},  53.},
{{2010, 7, 27, 0, 0, 0.},  58.},
{{2010, 7, 27, 0, 0, 0.},  25.}}}, 1];

The difference between daily, monthly, and yearly
is in how many elements SplitBy uses to match on.

{#[[1,1]],Tr@#[[All,2]]}& /@ SplitBy[data,#[[1,{1,3}]]&] (* daily *)

{{{2010, 8,  3, 0, 0, 0.},  38.},
{{2010, 8,  2, 0, 0, 0.}, 108.},
{{2010, 7, 30, 0, 0, 0.},  62.},
{{2010, 7, 29, 0, 0, 0.},   0.}, (* how did you get -10. here? *)
{{2010, 7, 28, 0, 0, 0.},  64.},
{{2010, 7, 27, 0, 0, 0.}, 136.}}

{#[[1,1]],Tr@#[[All,2]]}& /@ SplitBy[data,#[[1,{1,2}]]&] (* monthly *)

{{{2010, 8,  3, 0, 0, 0.}, 146.},
{{2010, 7, 30, 0, 0, 0.}, 262.}}

{#[[1,1]],Tr@#[[All,2]]}& /@ SplitBy[data,#[[1,{1,1}]]&] (* yearly *)

{{{2010, 8, 3, 0, 0, 0.}, 408.}}

```

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