[R] question about sum of (column) elements in R

[Jose Iparraguirre]

Hi,

Imagine the data you have is in a data frame, c, with columns a and b.
Then you can do this:

> res=tapply(b,c[,-2],sum) 
> res[is.na(res)]<-0
> res
  0   1   2   3   4 
 12  40  64 111  63

Hope it helps,
José

José Iparraguirre
Chief Economist
Age UK



-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of T Bal
Sent: 04 December 2012 07:59
To: r-help at r-project.org
Subject: [R] question about sum of (column) elements in R

Hi,
I have the following data:

0   12
1   10
1   4
1   6
1   7
1   13
2   21
2   23
2   20
3   18
3   17
3   16
3   27
3   33
4   11
4   8
4   19
4   16
4   9


In this data file I would like to sum the numbers of second column which
belong to the same number in the first column.
So the output would be:

0     12
1     40
2     64
        3     111
        etc.

Thank you.

Kind regards,
T. Bal

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