[R] Problem with SAGx Library
Rohit Vishal Kumar
rohitvk at vsnl.com
Wed Sep 21 17:30:12 CEST 2005
Dear All:
I am a newbie to R and as such i am posting this request for help.
I am trying to use R to compute the "Calinski Harabasz (CH) Index ". The
CH Index is available in the library SAGx.
The version of R i am running is 2.2.1.
I have my data in a CSV format which i read into R using the
read.table() command. After the data has been read i am loading in the
"SAGx" and "MASS" libraries.
According to the SAGx help files the command for running a CH
procedure is as follows:
caha(data, cluster)
where: "data" is the data matrix and "cluster" is a vector describing
the cluster membership consecutive numbers.
The commands that i give are as follows:
| > cl <- myclus(mydata, k=3)
| > caha(mydata, cl$cluster)
I get the following output
Error in "[.data.frame"(x, , cl == (i + min(cl) - 1)) :
undefined columns selected
I cannot make head or tail out of the error.
Strangely enough SAGx the procedure "gap" to calculate the GAP
statistic has the same format as CH. So when i give the command (shown
below) after several minutes of computation i get the value for the
statistic say 0.39765:
| > gap (mydata, cl$cluster)
[1] 0.39765
Am i doing something wrong when i am implementing caha?
As my knowledge of R is quite limited i shall be extremely grateful for
your help in this regard.
Thanking you once again.
Rohit Vishal Kumar
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