R help - Jun 2010 - how to 'average' one col wrt to another one

Hi, folks,

test=matrix(rep(letters[1:3],6),nrow=6,byrow=T)
test[2,]=letters[5:7]
test[4,]=c('e','f','i')
test[1,3]='i'
colnames(test)=c('leave','arrive','line')

The code will generate a sample dataset. I have thousands rows of data.

For the same 'leave' and 'arrive', how can I get the sum of
square of
percentages of 'line' for each combination of 'leave' and
'arrive'?

For the sample dataset, we have 5 combinations of 'leave' and
'arrive',
namely, 'ab', 'ef'

For 'ab', the line can be 'c' or 'i'. 1st row, it is
line 'i' (1/3), and
5&6th row (2/3), it is line 'c'.  then the sum of square of
percentage for
'ab' is (1/3)^2+(2/3)^2=0.56

For 'ef', it is 0.5^2+0.5^2=0.5

I would like the final dataset to be like as follows:

ab 0.56
ef   0.5
....

How to achieve it?

Thanks

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Is this the kind of thing you want?
> test <- matrix(rep(letters[1:3],6),nrow=6,byrow=T)
> test[2,] <- letters[5:7]
> test[4,] <- c('e','f','i')
> test[1,3] <- 'i'
> colnames(test) <- c('leave','arrive','line')
> test <- data.frame(test)
> tab <- with(test, table(paste(leave, arrive, sep=""), line))
> tab <- tab/rowsums(tab)
> 
> rowsums(tab^2)
   ab    ef 
0.625 0.500 
> 
Your 'ab' calculation I think may not be quite correct. 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of YI LIU
Sent: Thursday, 17 June 2010 11:28 AM
To: r-help at r-project.org
Subject: [R] how to 'average' one col wrt to another one

Hi, folks,

test=matrix(rep(letters[1:3],6),nrow=6,byrow=T)
test[2,]=letters[5:7]
test[4,]=c('e','f','i')
test[1,3]='i'
colnames(test)=c('leave','arrive','line')

The code will generate a sample dataset. I have thousands rows of data.

For the same 'leave' and 'arrive', how can I get the sum of
square of
percentages of 'line' for each combination of 'leave' and
'arrive'?

For the sample dataset, we have 5 combinations of 'leave' and
'arrive',
namely, 'ab', 'ef'

For 'ab', the line can be 'c' or 'i'. 1st row, it is
line 'i' (1/3), and
5&6th row (2/3), it is line 'c'.  then the sum of square of
percentage for
'ab' is (1/3)^2+(2/3)^2=0.56

For 'ef', it is 0.5^2+0.5^2=0.5

I would like the final dataset to be like as follows:

ab 0.56
ef   0.5
....

How to achieve it?

Thanks

	[[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Hi Yi,

Try this:

res <- with(data.frame(test), prop.table(table(paste(leave, arrive, sep
""), line), 1))
rowSums(res^2)

HTH,
Jorge


On Wed, Jun 16, 2010 at 9:28 PM, YI LIU <> wrote:
> Hi, folks,
>
> test=matrix(rep(letters[1:3],6),nrow=6,byrow=T)
> test[2,]=letters[5:7]
> test[4,]=c('e','f','i')
> test[1,3]='i'
> colnames(test)=c('leave','arrive','line')
>
> The code will generate a sample dataset. I have thousands rows of data.
>
> For the same 'leave' and 'arrive', how can I get the sum of
square of
> percentages of 'line' for each combination of 'leave' and
'arrive'?
>
> For the sample dataset, we have 5 combinations of 'leave' and
'arrive',
> namely, 'ab', 'ef'
>
> For 'ab', the line can be 'c' or 'i'. 1st row, it
is line 'i' (1/3), and
> 5&6th row (2/3), it is line 'c'.  then the sum of square of
percentage for
> 'ab' is (1/3)^2+(2/3)^2=0.56
>
> For 'ef', it is 0.5^2+0.5^2=0.5
>
> I would like the final dataset to be like as follows:
>
> ab 0.56
> ef   0.5
> ....
>
> How to achieve it?
>
> Thanks
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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