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

• To: mathgroup at smc.vnet.net
• Subject: [mg111899] Re: How can I totalize by month, by year?
• From: David Carraher <david_carraher at terc.edu>
• Date: Wed, 18 Aug 2010 07:04:52 -0400 (EDT)

Hi Leandro,

Here's one approach.  Other folks will find other ways, I'm sure....

Below are your data (minus the outer pair of curly braces).

In[1]:=

data = {
{{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.}};

(*
Here's one approach
GatherBy gathers the transactions from like dates.
Transpose puts the amounts for each data into lists.
Plus sums the list of amounts

*)

In[2]:=
Transpose /@   GatherBy[data, First] /. {dates_, sum_List} :> {
First[dates], Plus @@ sum}

Out[2]=
{
{{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.},
{{2010, 7, 28, 0, 0, 0.}, 64.},
{{2010, 7, 27, 0, 0, 0.}, 136.}}

From:   "Leandro Tenfen" <leandrotenfen at hotmail.com>
To:     mathgroup at smc.vnet.net
Date:   08/17/2010 07:52 AM
Subject: [mg111899]        [mg111895] How can I totalize by month, by year?

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

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