[R] splitting data

[David Winsemius]

On Sep 8, 2014, at 12:08 PM, eliza botto wrote:

> Dear R members,
> 
> I have this data frame of 100 years in the following format
> 
> year            month       day         A           B           C         D
> 
> where  A,B,C and D are item number sold each day. I am trying 
> 
> 1-split the data w.r.t the monthly values for each year
> 
> 2-then, sum them up
> 
> I am pasting here just a part of data to make it more clearer
> 
> structure(list(year = c(1961, 1961, 1961, 1961, 1961, 1961, 1961, 
> 1961, 1961, 1961, 1961, 1961), month = c(1, 1, 1, 1, 1, 1, 1, 
> 1, 1, 1, 1, 1), day = 1:12, A = 1:12, B = 3:14, C = 6:17, D = 16:27), .Names = c("year", 
> "month", "day", "A", "B", "C", "D"), row.names = c(NA, 12L), class = "data.frame")
> 
> I initially tried to use "dcast" command but for no use.
> 

This is typical use for base function aggregate:

> with( dfrm, aggregate(dfrm[4:7], dfrm[1:2], FUN=sum))
  year month  A   B   C   D
1 1961     1 78 102 138 258

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Please stop posting in plain text. (You have already been asked multiple times.)

-- 

David Winsemius
Alameda, CA, USA