Subset the Combination Matrix
Subset the Combination Matrix
## S3 method for class 'comb_mat' x[i, j, drop = FALSE]
x |
A combination matrix returned by |
i |
Indices on rows. |
j |
Indices on columns. |
drop |
It is always reset to |
If sets are on rows of the combination matrix, the row indices correspond to sets and column indices correspond to combination sets, and if sets are on columns of the combination matrix, rows correspond to the combination sets.
If the index is one-dimension, e.g. x[i], the index always corresponds to the combination sets.
You should not subset by the sets. It will give you wrong combination set size. The subsetting on sets are only used internally.
This subsetting method is mainly for subsetting combination sets, i.e., users
can first use comb_size to get the size of each combination set, and filter them
by the size.
set.seed(123)
lt = list(a = sample(letters, 10),
b = sample(letters, 15),
c = sample(letters, 20))
m = make_comb_mat(lt)
m2 = m[, comb_size(m) >= 3]
comb_size(m2)
m[comb_size(m) >= 3]Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.