Within standard R, it is common to take objects that are lists (as a data.frame
is)
apart and apply some function and recombine them. So using my example in an
earlier
message, and hoping this text-mode message is readable, try something like this
to multiply each column of a data.frame by the same vector and return the
data.frame.
Note the multiply operation as a function is denoted by `*` including the grave
accents.
> orig <- data.frame(a=1:3, b=3:1, c=c(10,15,20))
> orig
a b c
1 1 3 10
2 2 2 15
3 3 1 20
> vec <- c(1, 10, 100)
> as.data.frame(lapply(orig, `*`, vec))
a b c
1 1 3 10
2 20 20 150
3 300 100 2000
You can also use sapply but it returns more of a matrix than a data.frame:
> sapply(orig, `*`, vec)
a b c
[1,] 1 3 10
[2,] 20 20 150
[3,] 300 100 2000
> class(sapply(orig, `*`, vec))
[1] "matrix" "array"
Again, there are an amazing number of ways to do anything in R.
-----Original Message-----
From: Kelly Thompson <kt1572...@gmail.com>
Cc: r-help@r-project.org <r-help@r-project.org>
Sent: Sat, Apr 9, 2022 12:49 pm
Subject: Re: [R] Multiplying each row of data.frame by a row in another
data.frame
Does this produce the desired results?
Also, even if this produces your desired results, I am not sure it is
the "best" way to do this. There might be better ways.
data.frame( t ( t(val_df) * (weights$value) )
On Fri, Apr 8, 2022 at 9:57 PM maithili_shiva--- via R-help
<r-help@r-project.org> wrote:
>
> Dear R forum
> weights <- data.frame(id = c("ABC", "DEF", "ONS"), value = c(1, 2, 5))
> val_df <- data.frame(ABC = c(10, 20, 10, 10, 10), DEF = c(1, 2, 10, 2, 5),
> ONS = c(100, 100, 200, 100, 100))
>
> > weights
> id value1 ABC 12 DEF 23 ONS 5
>
> > val_df
> ABC DEF ONS1 10 1 1002 20 2 1003 10 10 2004 10 2
>1005 10 5 100
> I wish to multilpy each row of data.frame val_df by value column of
> data.frame weights.
> ABC DEF ONS1 10*1 1*2 100*52 20*1 2*2 100*53 10*1 10*2
>200*54 10*1 2*2 100*55 10*1 5*2 100*5
> ie I wish to have output as
> OUTPUT
> ABC DEF ONS1 10 2 5002 20 4 5003 10 20
> 10004 10 4 5005 10 10 500
>
> O have tried sweep function, even matrix multiplcation etc, but nothing seems
> to be working.
> Please guide
> Regards
> Maithili
>
> [[alternative HTML version deleted]]
>
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.
