[R] How to multiple the vector and variables from dataframe

[arun]

HI Meng,


Just try:
rep(z,rach=nrow(dat))
#[1]   0.1  10.0 100.0
 rep(z,chair=nrow(dat))
#[1]   0.1  10.0 100.0
rep(z,times=nrow(dat))
#[1]   0.1  10.0 100.0   0.1  10.0 100.0   0.1  10.0 100.0
 rep(z,each=nrow(dat))
#[1]   0.1   0.1   0.1  10.0  10.0  10.0 100.0 100.0 100.0
 rep(z,nrow(dat))
#[1]   0.1  10.0 100.0   0.1  10.0 100.0   0.1  10.0 100.0

#and
dat*rep(z,times=nrow(dat))
 #    x1    x2    x3
#1   0.1   0.4   0.7
#2  20.0  50.0  80.0
#3 300.0 600.0 900.0
 dat*rep(z,nrow(dat))
#     x1    x2    x3
#1   0.1   0.4   0.7
#2  20.0  50.0  80.0
#3 300.0 600.0 900.0
dat*rep(z,each=nrow(dat))
#   x1 x2  x3
#1 0.1 40 700
#2 0.2 50 800
#3 0.3 60 900

A.K.




----- Original Message -----
From: meng <laomeng_3 at 163.com>
To: Andrius Druzinis <andrius.druzinis at gmail.com>
Cc: R help <r-help at r-project.org>
Sent: Sunday, December 30, 2012 9:24 PM
Subject: Re: [R] How to multiple the vector and variables from dataframe

Hi Andrius:
Thanks for your reply.
Your answer: dat*rep(z,each=nrow(dat)) works well.

But a strange thing happened:
dat<-data.frame(x1=1:3,x2=4:6,x3=7:9)
z<-c(0.1,10,100)
#I wanna 0.1*x1,10*x2,100*x3

I type:
dat*rep(z,rach=nrow(dat))
"rach" is "each" indeed,but I type "rach" mistakenly.
What's strange to me is :No error reply appears,but show me the result:
> dat*rep(z,rach=nrow(dat))
     x1    x2    x3
1   0.1   0.4   0.7
2  20.0  50.0  80.0
3 300.0 600.0 900.0
Why does it happen,and what "rach" means?

Many thanks.










At 2012-12-31 00:08:26,"Andrius Druzinis" <andrius.druzinis at gmail.com> wrote:

Hi Meng, 


A one-liner would be
dat*rep(z, each=nrow(dat))


Cheers, 
Andrius



2012/12/30 meng <laomeng_3 at 163.com>
hi all:
Here's a dataframe(dat) and a vector(z):

dat:
x1     x2    x3
0.2   1.2   2.5
0.5   2      5
0.8   3      6.2

> z
[1]  10 100 100

I wanna do the following:
10*x1,100*x2,1000*x3

My solution is using the loop for z and dat(since the length of z is the same as ncol  of dat),which is tedious.
I wanna an efficient solution to do it .

Any help?

Many thanks!

My best



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R-help at r-project.org mailing list
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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.