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- Original Message ----
> From: Peter Francis
> To: r-help@r-project.org
> Sent: Wed, January 12, 2011 2:38:19 AM
> Subject: [R] Sum by column
>
> Dear List,
>
> I have a ques
David and Josh,
Thanks very much for your help, it is much appreciated.
Peter
On 12 Jan 2011, at 14:28, David Winsemius wrote:
There are two functions you need to become familiar with:
?tapply
?ave
If you wanted these summed values to be placed in another column of the same
dataframe, you w
Hi Peter,
R has some fairly flexible ways of passing values of some variable (X)
by another (the INDEX) to different FUNctions. Here is an example
using your data:
## your email data, in convenient form
dat <- structure(list(ED = c(21.809467, 36.229566, 51.861284, 11.36232,
27.264634, 12.261986,
There are two functions you need to become familiar with:
?tapply
?ave
If you wanted these summed values to be placed in another column of
the same dataframe, you would use ave. If you wanted a new structure
(somewhat shorter) you would use tapply with sum as the function. E. g:
tapply(eco
Dear List,
I have a question of convenience,
I am looking to sum the values of one column based on another column - a
example may help explain better!
ED ECOCODE
21.809467 AA0101
36.229566 PA1201
51.861284 PA1201
11.36232PA1201
27.264634 PA12
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