PreviousDate {Transition} | R Documentation |
Find Previous Test Date for Subject
Description
get_prev_dates()
identifies the previous test date for individual subjects and timepoints
in a longitudinal study.
add_prev_date()
interpolates these previous test dates into a data frame for further analysis.
Usage
add_prev_date(
object,
subject = "subject",
timepoint = "timepoint",
result = "result"
)
get_prev_date(
object,
subject = "subject",
timepoint = "timepoint",
result = "result"
)
Arguments
object |
a |
subject |
|
timepoint |
|
result |
|
Details
See Transitions
details.
Value
add_prev_date() |
A |
get_prev_date() |
An |
See Also
data.frame
, Dates
, ordered factor
.
Other transitions:
PreviousResult
,
Transitions
,
uniques()
Examples
## Continuing example from `add_transitions()`
# subject, timepoint and result arguments all defaults and required types
Blackmore |> str()
# Integer vector of the previous test dates
get_prev_date(Blackmore)
# Add column of previous test dates to data frame
add_prev_date(Blackmore) |> head(32)
rm(Blackmore)
###
## Example on formatting numeric values as R dates
# Data frame containing year as numeric: 2018 to 2025
(df <- data.frame(
subject = rep(1001:1003),
timepoint = rep(2018:2025, each = 3),
result = gl(3, 4, lab = c("jolly", "good", "show"), ordered = TRUE)
))
# Convert to R dates
df <- transform(df,
timepoint = as.Date(paste(timepoint, "01", "01", sep = "-"))
)
# Add column of test result transitions (defaults: cap = 0, modulate = 0)
(df <- add_transitions(df))
# Format R dates just to show the year
transform(df, timepoint = format(timepoint, "%Y"))
# Data frame containing year and month as numeric: July 2024 to June 2025
(df <- data.frame(
subject = 1001:1002,
year = rep(2024:2025, each = 12),
month = rep(c(7:12, 1:6), each = 2),
result = gl(2, 3, lab = c("low", "high"), ordered = TRUE)
))
# Convert to R dates
df <- transform(df, timepoint = as.Date(paste(year, month, "01", sep = "-")))
# Add column of test result transitions (defaults: cap = 0, modulate = 0)
(df <- add_transitions(df))
# Format R dates just to show the month and year
transform(df, timepoint = format(timepoint, "%b-%Y"))
rm(df)