When you select a single row from a matrix, the dimsion is lost:
n <- matrix(nrow = 3, ncol = 5)
dim(n)
[1] 3 5
dim(n[1,])
NULL
dim(n[2,])
NULL
This doesn't happen if you select more than one row:
dim(n[1:2,])
[1] 2 5
This is causing trouble. SCENARIO: when I filter out unqualified sampled
data, I was not unaware that only one row of data qualifies, and the
resulted selected data thus doesn't have dimension. I would call matrix[,3]
and get an error.
One way to mend this is to re-assign the dimension to the result set, but
that destories column names...
selected = n[1,]
selected
unixtime agio count ask bid
NA NA NA NA NA
dim(selected)
NULL
dim(selected) <- c(1,5)
selected
[,1] [,2] [,3] [,4] [,5]
[1,] NA NA NA NA NA
Is there a way to retain dimension when selecting only one row from a
matrix?
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
