[R] How to multiply all dataframe rows by another dataframe's columns

[Moshe Olshansky]

Below is one way to do this:

> Loc1.alleles     <- c(1,5,6,7,8)
> Loc1.Freq        <- c(0.35, 0.15, 0.05, 0.10, 0.35)
> Loc1             <- cbind( Loc1.alleles,Loc1.Freq)
> X            <- data.frame(Loc1)
> Loc2.alleles  <- c(1,4,6,8)
> Loc2.Freq     <- c(0.35, 0.35, 0.10, 0.20)
> Loc2          <- cbind(Loc2.alleles, Loc2.Freq)
> Y             <- data.frame (Loc2)
> 
> Z<-Y[,2] %o% X[,2]
> Z
       [,1]   [,2]   [,3]  [,4]   [,5]
[1,] 0.1225 0.0525 0.0175 0.035 0.1225
[2,] 0.1225 0.0525 0.0175 0.035 0.1225
[3,] 0.0350 0.0150 0.0050 0.010 0.0350
[4,] 0.0700 0.0300 0.0100 0.020 0.0700
> dim(Z) <- c(prod(dim(Z)),1)
> Z
        [,1]
 [1,] 0.1225
 [2,] 0.1225
 [3,] 0.0350
 [4,] 0.0700
 [5,] 0.0525
 [6,] 0.0525
 [7,] 0.0150
 [8,] 0.0300
 [9,] 0.0175
[10,] 0.0175
[11,] 0.0050
[12,] 0.0100
[13,] 0.0350
[14,] 0.0350
[15,] 0.0100
[16,] 0.0200
[17,] 0.1225
[18,] 0.1225
[19,] 0.0350
[20,] 0.0700
> 

Regards,

Moshe.

--- Luke Neraas <lukasneraas at gmail.com> wrote:

> Hello,
> 
> I have two data frames, X and Y, with two columns
> each and different numbers
> of rows.
> 
> # creation of data frame X
> 
> Loc1.alleles     <- c(1,5,6,7,8)
> Loc1.Freq        <- c(0.35, 0.15, 0.05, 0.10, 0.35)
> Loc1             <- cbind( Loc1.alleles,Loc1.Freq)
> X            <- data.frame(Loc1)
> 
> #creation of data frame Y
> 
> Loc2.alleles  <- c(1,4,6,8)
> Loc2.Freq     <- c(0.35, 0.35, 0.10, 0.20)
> Loc2          <- cbind(Loc2.alleles, Loc2.Freq)
> Y             <- data.frame (Loc2)
> 
> I would like a flexible way to multiply each element
> of second column of the
> X data frame
> by each element of the second column of the Y data
> frame.
> 
>  example of what the operation need to do: 
> X[1,2]*Y[,2] ;
> X[2,2]*Y[,2].............X[4,2]*Y[,2]
> 
> I have worked on a variety of "for" loops to get
> this to work without
> success.
> 
> The final result should look like a column like this
> 
>     "all_X[,2] * all_Y[,2]"
>         0.1225
>         0.1225
>         0.0350
>         0.0700
>         0.0525
>         0.0525
>         0.0150
>         0.0300
>         0.0175
>         0.0175
>         0.0050
>         0.0100
>         0.0350
>         0.0100
>         0.0200
>         0.1225
>         0.1225
>         0.0350
>         0.0700
> 
> any help would be greatly appreciated
> 
> Luke Neraas
> 
> lukasneraas at gmail.com
> 
> 	[[alternative HTML version deleted]]
> 
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