Skip to content

Ops.factor(point1, point2) : - not meaningful for factors

2 messages · nadiah, Rui Barradas

nadiah
# 
Hi, can anyone help me in this problem :(. I am a total beginner in R
software.  It took me 2 days just to look into this problem.  Due to this
problem. I cant do looping. i want to find the distance between x and DSi
i       Si
1 1  (5, 20)
2 2  (20, 2)
3 3 (25, 32)
4 4  (8, 39)
5 5 (10, 17)
6 6 (35, 20)
7 7 (38, 10)
'data.frame':   7 obs. of  2 variables:
 $ i : int  1 2 3 4 5 6 7
 $ Si: Factor w/ 7 levels "(10, 17)","(20, 2)",..: 6 2 3 7 1 4 5
+ {
+ diff <- point1-point2
+ distance <- sqrt(sum(diff^2))
+ distance
+ }
[1] NA
Warning message:
In Ops.factor(point1, point2) : - not meaningful for factors
Regards,
Nadiah



--
View this message in context: http://r.789695.n4.nabble.com/Ops-factor-point1-point2-not-meaningful-for-factors-tp4644971.html
Sent from the R help mailing list archive at Nabble.com.
Rui Barradas
# 
Hello,

First of all, it's not a good idea to use  'dist' and 'diff' since they 
already are names of R functions.
As for the problem, your column DSi$Si is not a column of 2-dim points, 
it's not even a vector of numbers, it's a categorical variable,  a 
factor, like you can see in the output of str(). See the difference with 
an example, using your first two "points".


mydist <- function (point1, point2){
     dff <- point1 - point2
     distance <- sqrt(sum(dff^2))
     distance
}

x <- c(5, 20)  # these are vectors representing
y <- c(20, 2)  # 2-dim points

dist(matrix(c(x, y), ncol=2))
mydist(x, y)


Also, it's better to post data using ?dput().

Hope this helps,

Rui Barradas
Em 04-10-2012 09:07, nadiah escreveu: