collapse_lattice {CTNote} | R Documentation |
Given a vector of simple study visits patterns, combine them into a more complex study visit lattice
collapse_lattice(lattice_patterns, times)
lattice_patterns |
A character vector of simple study design lattices |
times |
An integer vector indicating the number of times to repeat each
simple lattice. The length of the |
This function was designed to handle outcomes where the clinical
trial protocol has staggered or non-sequential visits. For example, if we
observed the pattern "-ooo"
, in most cases we would interpret this
to mean that the subject was present in the clinic for the first visit, but
missed the next three visits. Some trial outcomes would then count the
three missing visits as all positive or as a relapse. However, this use
pattern could have been observed late during subject follow-up, during
which time the protocol could be that the subject was only required to
visit the clinic monthly (so long as the supplied UDS was negative).
This function is basically a wrapper around the paste0
function with collapse = ""
. We added support to repeat subpatterns.
The combined lattice pattern, built up from combinations of the smaller lattices.
# Example 1: a 16 week observation period with visits every 4 weeks:
# "___o___o___o___o"
collapse_lattice(
lattice_patterns = "___o",
times = 4
)
# Example 2: 24 week observation period with weekly visits for the first
# 12 weeks, then monthly visits (during the second week) thereafter:
# "oooooooooooo_o___o___o__"
collapse_lattice(
lattice_patterns = c("o", "_o__"),
times = c(12, 3)
)
# Example 3: 6 week observation period with clinic visits on set days,
# M-W-F for the first 3 weeks, then Monday only for the next 3 weeks:
# "o_o_o__o_o_o__o_o_o__o______o______o______"
collapse_lattice(
lattice_patterns = c("o_o_o__", "o______"),
times = c(3, 3)
)