a vector of row names. This can be a vector giving
the actual row names, or a single number giving the column of the
table which contains the row names, or character string giving the
name of the table column containing the row names.
If there is a header and the first row contains one fewer field than
the number of columns, the first column in the input is used for the
row names. Otherwise if row.names
is missing, the rows are
numbered.
Using row.names = NULL
forces row numbering. Missing or
NULL
row.names
generate row names that are considered
to be ‘automatic’ (and not preserved by as.matrix
).