[EMAIL PROTECTED] said the following on 2007-01-05 04:18:
[Using R 2.2.0 on Windows XP; OK, OK, I will update soon!]
I have noticed some undesirable behaviour when applying
ifelse to a data frame. Here is my code:
A - scan()
1.00 0.00 0.00 0 0.0
0.027702 0.972045
PROTECTED]
To: [EMAIL PROTECTED]
Copies to: r-help@stat.math.ethz.ch
Subject:Re: [R] ifelse on data frames
It can be explained.
class(A)
[1] data.frame
length(A)
[1] 5
class(A==0)
[1] matrix
length(A==0)
[1] 10
class(-A*log(A))
[1
On Friday 05 January 2007 12:34, Petr Pikal wrote:
Hi
you could use also another approach in case of data
frames
A - as.data.frame(A)
A0 - -A*log(A)
A0[is.na(A0)] - 0
I think you meant A0[which(is.na(A0))] - 0
which changes NaN's to zeroes
HTH
Petr
Regards
``MrJ Man'' wrote:
On Friday 05 January 2007 12:34, Petr Pikal wrote:
Hi
you could use also another approach in case of data
frames
A - as.data.frame(A)
A0 - -A*log(A)
A0[is.na(A0)] - 0
I think you meant A0[which(is.na(A0))] - 0
He most certainly DOES NOT mean this!
[Using R 2.2.0 on Windows XP; OK, OK, I will update soon!]
I have noticed some undesirable behaviour when applying
ifelse to a data frame. Here is my code:
A - scan()
1.00 0.00 0.00 0 0.0
0.027702 0.972045 0.000253 0 0.0
A - matrix(A,nrow=2,ncol=5,byrow=T)
A == 0
It can be explained.
class(A)
[1] data.frame
length(A)
[1] 5
class(A==0)
[1] matrix
length(A==0)
[1] 10
class(-A*log(A))
[1] data.frame
length(-A*log(A))
[1] 5
as you can see, the result of A==0 is matrix with length=10, while the
result of -A*log(A) is still data.frame with length=5.
