How to multiply matrix element by scalar in R

Asked Oct 05 '15 at 04:43

Active Oct 05 '15 at 04:57

Viewed 241 times

I am struggling to do this simple multiplication, I want to multiply matrix element with constant :

mydata <- read.csv("c:/mydata.csv",header=F,dec=",")
5*mydata[1,3]

I am getting following error :

Warning message:
In Ops.factor(mydata[1, 3], 0.1) : ‘*’ not meaningful for factors

Whats wrong with the code?

edited Oct 05 '15 at 04:57

asked Oct 05 '15 at 04:43

Siddhesh

How did you create `mydata`? – Oct 05 '15 at 04:43
I imported it using read.csv – Siddhesh Oct 05 '15 at 04:44
mydata<-read.csv("c:/mydata.csv",header=F,dec=",") – Siddhesh Oct 05 '15 at 04:45
1

you are trying to multiply a scalar to a factor, thats why the error. Check 3rd column in your data. – Amrita Sawant Oct 05 '15 at 04:59
@Amrita Thanks. Is there any way to convert it to numeric matrix ? – Siddhesh Oct 05 '15 at 05:01
1

Try adding `stringsAsFactors = FALSE` in `read.csv()` then try it again. Otherwise please show a few lines of the top of the file – Rich Scriven Oct 05 '15 at 05:04
we cannot help much without looking at your data and without knowing what result you want to get . You can try 5 * as.numeric(mydata[1,3]) and see if this is what you need. – Amrita Sawant Oct 05 '15 at 05:07
@Richard : Thanks. But now i am getting error as : **Error in 5 * mydata[1, 3] : non-numeric argument to binary operator** – Siddhesh Oct 05 '15 at 05:08
[link]http://stackoverflow.com/questions/17506691/converting-from-a-list-to-numeric-in-r <-- This thread was helpful. I used data.matrix(mydata). – Siddhesh Oct 05 '15 at 05:13
Are you sure you don't have a header in that file? – ekstroem Oct 05 '15 at 05:59
@ ekstroem : yes, it doesnt have header – Siddhesh Oct 05 '15 at 06:01

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