/usr/lib/R/site-library/abind/INDEX is in r-cran-abind 1.4-5-1.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | abind Combine multi-dimensional arrays
acorn Return a corner of an array object (like head)
adrop Drop dimensions of an array object
afill Fill an array with subarrays
asub Arbitrary subsetting of array-like objects at
specified indices
|