[R] weighing proportion of rowSums in dataframe

[Eik Vettorazzi]

Hi Alain,
here is a one-liner for a df without the rowSum column

df<-data.frame(id=c("x01","x02","x03","x04","x05","x06"),a=c(1,2,NA,4,5,6),b=c(2,4,6,8,10,NA),c=c(NA,3,9,12,NA,NA))

(df$wSum<-apply(sweep(df[,-1],1,rowSums(df[,-1],na.rm=T),"/"),1,function(x)sum(x*w,na.rm=T)))

hth.

Am 06.02.2013 14:17, schrieb D. Alain:
> Dear R-List, 
> 
> 
> I am sure there must be a very simple way to do this - I just do not know how...
> This is what I want to do: 
> 
> 
> #my dataframe
> 
> df<-data.frame(id=c("x01","x02","x03","x04","x05","x06"),a=c(1,2,NA,4,5,6),b=c(2,4,6,8,10,NA),c=c(NA,3,9,12,NA,NA),sum=c(3,9,15,24,15,6))
> 
>    id    a     b     c   sum
> 1 x01  1     2    NA   3
> 2 x02  2     4     3      9
> 3 x03 NA  6     9     15
> 4 x04  4     8    12    24
> 5 x05  5    10   NA  15
> 6 x06  6   NA  NA   6
> 
> 
> #my weights
> w<-c(10.5,9,12.8)
> 
> #now I want to calculate the proportion of the rowsum = "sum" of every other number in the row, that is df[1,2]/df[1,5], df[1,3]/df[1,5], ...
> 
> 
> #e.g. 
> 
> 
> df.prop
> 
> 
>    id         a         b           c          sum 
> 1 x01      0.33     0.66     NA        3
> 2 x02      0.22     0.44     0.33     9
> 3 x03     NA       0.4       0.6       15
> 4 x04      0.16     0.33     0.5        24
> 5 x05      0.33     0.66     NA       15
> 6 x06      1           NA     NA       6
> 
> #and then calculate a rowsum, were each column is weighed by its associated factor in the vector "w", i.e. all entries in column df$a should be weighed by the factor 10.5, df$b by 9 and df$c by 12.8 and then summed up to a weighed rowsum (wrowsum=10.5*0.33+9*0.66).
> 
> Any suggestions how to achieve this in a simple way with dataframes that have 9000 rows and 44 columns (so I cannot do this row by row) - sorry, if this is to easy a question.
> 
> Thank you very much in advance!
> 
> Best wishes
> 
> Alain
> 	[[alternative HTML version deleted]]
> 
> 
> 
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Eik Vettorazzi

Department of Medical Biometry and Epidemiology
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