[R] Performing multiplication on duplicate values

[arun]

Hi,
May be this helps:
dat1<-read.table(text="
Reference_Position Reference_Allele Variant_Allele Variant_Frequency   AAC_Variant
                   16                G              A         91.833811   Val6Met,Met
                   52                G              A         93.969466      Val18Ile
                   64                G              T         94.155381      Val22Phe
                   73                C              A         94.293478      Gln25Lys
                 131                G              A         94.268168      Arg44Lys
                 64                  G              A         92.947658      Ser48Asn
         72                  G              A          85.9468       Gln25Phe   
                 62                  C              A          92.6583       Arg42Lys 
                 72                  G              T          96.86688      Ser48Lys
",sep="",header=TRUE,stringsAsFactors=FALSE) 
dat2<-dat1[,c(1,4)][duplicated(dat1$Reference_Position)|duplicated(dat1$Reference_Position,fromLast=TRUE),]
dat3<-do.call(rbind,lapply(split(dat2,dat2$Reference_Position),function(x) (x[1,2]*x[2,2])/100))
dat4<-data.frame(Reference_Position=row.names(dat3),Value=dat3)
 row.names(dat4)<-1:nrow(dat4)
merge(dat1[,c(1,4)],dat4,by="Reference_Position",all=TRUE)
#  Reference_Position Variant_Frequency    Value
#1                 16          91.83381       NA
#2                 52          93.96947       NA
#3                 62          92.65830       NA
#4                 64          94.15538 87.51522
#5                 64          92.94766 87.51522
#6                 72          85.94680 83.25398
#7                 72          96.86688 83.25398
#8                 73          94.29348       NA
#9                131          94.26817       NA

A.K.




----- Original Message -----
From: JDINIS <jorgemdinis at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Monday, October 29, 2012 12:27 PM
Subject: [R] Performing multiplication on duplicate values

Hello all,  thank you for your help. The task I need to perform is difficult
to explain so I apologize a head of time for any confusion.

I have a data frame with these colnames() Reference_Position,
Reference_Allele, Variant_Allele, Variant_Frequency,   AAC_Variant. If a
value is duplicated in the "Reference_Position" column, I would both of
their "Variant_Frequency" values multiplied and inserted into a new data
frame.

example below: reference position 64 is repeated,  multiple 94.155381 by
92.947658 and insert value into "Value".

Because I do not know how to best explain this or phrase it into a logical
questions, here is a before and after. Also, if you could explain the code a
bit, that would be appreciated as well- teach and person to fish!


Before

>dat
[Reference_Position] [Reference_Allele] [Variant_Allele] [Variant_Frequency]  
[AAC_Variant]
                   16                G              A         91.833811  
Val6Met,Met
                   52                G              A         93.969466    
Val18Ile
                   64                G              T         94.155381    
Val22Phe
                   73                C              A         94.293478    
Gln25Lys
                 131                G              A         94.268168    
Arg44Lys
                 64                  G              A         92.947658    
Ser48Asn
After

>dat
[Reference_Position]    [Variant_Frequency]       [Value]
                   16                91.833811                            
NA
                   52                93.969466                            
NA
                   64                94.155381                        
85.152215
                   73                94.293478                           NA
                 131                94.268168                           NA
                   64                92.947658                        
85.152215




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