a = matrix(
c(2, 4, 3, 1, 5, 7), # the data elements
nrow=2, # number of rows
ncol=3, # number of columns
byrow = TRUE) # fill matrix by rows
class( (a[1,])
[1] "numeric"
class(a[c(1,2),])
[1] "matrix"
class(as.matrix(a[1,]))
[1] "matrix"
#### a row changed to be a column ????matrix(a[ 1, ],ncol=3) #
n = c(2, 3, 5)
s = c("aa", "bb", "cc")
b = c(TRUE, FALSE, TRUE)
df = data.frame(n, s, b)
class( df[1,])
[1] "data.frame"
class(df[c(1,2),])
[1] "data.frame"
class(as.matrix(df[1,]))
[1] "matrix"
