Re: [R] Strange problem.

[Spencer Graves]

	  Note also the warning:  "the condition has length > 1 and only the 
first element will be used in: if (n < 9543) 0 else prior(n)/n".  The 
problem is that "if" is not vectorized:  "if(n<9543)" is interpreted as 
"if(n[1]<9543)", which then produces a scalar output, 0, which 
presumably then generates the error message "x and y lengths differ".

	  Try "ifelse" instead, so "post" becomes:

post<-function(n){
 ifelse(n < 9543, 0, prior(n)/n)
 }
	  Then plot(post,1,15000) seemed to work fine for me.

hope this helps.  spencer graves

Yannong.Dong-1 wrote:
Hi, everyone,
    I am a new user of R. Recently, I tried the following commands, but couldn't make 
them work. If any one of you has some ideas about it, please help me. The commands are

std<-1000
mean<-8000
prior<-function(n){1/(sqrt(2*pi)*std)*exp(-1.0*(n-mean)^2/(2*std^2))}
plot(prior,1,15000)
post<-function(n){
+ if(n < 9543) 
+  0
+ else
+  prior(n)/n
+ }

plot(post,1,15000)  # This command didn't work. The error message is " x and y lengths differ "


I was really confused about it because the first function "prior" can work well. I think I must make something wrong stupidly, but could not find it. If you can help me about it, it would be very helpful. Thanx a lot in advance.

   Rgds, 
   Yannong Dong

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