| longitudinal {longitudinal} | R Documentation |
Data Structure for Longitudinal Data
Description
The data type longitudinal stores multiple time series data. It allows repeated
measurements, irregular sampling, and unequal temporal spacing of the time points.
as.longitudinal converts a matrix into a longitudinal object. The columns of the
input matrix are considered as individual variables (time series). The rows contain the
measurements in temporal order (for instance, rows 1-10 could contain 10 repeated measurements taken at
time point 1, rows 11-20 further 10 measurements taken at time point 2, and so on).
The dates for the time points can be specified with the argument times and need not
be equally spaced. With the argument repeats it is possible to specify the number
of measurements per time point (this may be different from time point to time point). In the resulting
longitudinal matrix object the row names will indicate both the time points and the
repetition number (e.g., "10-1", "10-2", "10-3", ..., "20-1", "20-2", "20-3", etc.).
is.longitudinal checks whether a matrix has the longitudinal attributes.
The functions summary, print, plot are the standard generic functions
adapted to longitudinal objects.
Usage
as.longitudinal(x, repeats=1, time)
is.longitudinal(x)
## S3 method for class 'longitudinal'
summary(object, ...)
## S3 method for class 'longitudinal'
print(x, ...)
## S3 method for class 'longitudinal'
plot(x, series=1, type=c("median", "mean"), autolayout=TRUE, ...)
Arguments
x, object |
Time series data, contained in a |
repeats |
Integer, or a vector of integers, that specifies the number of available measurements per time point. If only one number is given then it is assumed the time series is regularly sampled. If instead a vector is specified, then each time point may have a different number of samples. |
time |
A vector with the dates for the time points. If not specified, equally spaced time points 1, 2, 3, ... are assumed. |
series |
Number, or a vector of numbers, that indicates which time series (=variables and columns of x) are plotted. |
type |
Determines whether the plotted line corresponds to the mean or median value of the samples per time point (default: "median"). |
autolayout |
determine the number of columns and rows in the plot automatically in the display of multiple time series (default: TRUE). |
... |
Additional optional parameters |
Value
as.longitudinal returns a longitudinal object.
is.longitudinal returns TRUE or false.
Author(s)
Korbinian Strimmer (https://strimmerlab.github.io).
See Also
Examples
# load "longitudinal" library
library("longitudinal")
# load data set
data(tcell)
is.longitudinal(tcell.34)
attributes(tcell.34)
tcell.34[,1:3]
# how many samples and how many genes?
dim(tcell.34)
summary(tcell.34)
# plot first nine time series
plot(tcell.34, 1:9)
#####
# an artificial example with repeated measurements, irregular sampling, and unequal spacing
m <- matrix(rnorm(200), 50, 4)
z <- as.longitudinal(m, repeats=c(10,5,5,10,20), time=c(2,8,9,15,16))
plot(z, 1:4)