shift: Shift a time series object

In bbuchsbaum/fmrireg: R package for the anlysis of fmri data

Shift a time series object

Description

Apply a temporal shift to a time series object. This function shifts the values in time while preserving the structure of the object. Common uses include:

alignment

Aligning regressors with different temporal offsets

derivatives

Applying temporal derivatives to time series

correction

Correcting for timing differences between signals

Usage

shift(x, ...)

Arguments

x	An object representing a time series or a time-based data structure
...	Additional arguments passed to methods. Common arguments include: offset Numeric; amount to shift by (positive = forward, negative = backward) pad Value to use for padding shifted regions (default = 0)

Value

An object of the same class as the input, with values shifted in time:

Values

Values are moved by the specified offset

Structure

Object structure and dimensions are preserved

Padding

Empty regions are filled with padding value

See Also

regressor(), evaluate()

Examples

# Create a simple time series with events
event_data <- data.frame(
  onsets = c(1, 10, 20, 30),
  run = c(1, 1, 1, 1)
)

# Create sampling frame
sframe <- sampling_frame(blocklens = 50, TR = 2)

# Create regressor from events
reg <- regressor(
  onsets = event_data$onsets,
  sampling_frame = sframe
)

# Shift regressor forward by 2 seconds
reg_forward <- shift(reg, offset = 2)

# Shift regressor backward by 1 second
reg_backward <- shift(reg, offset = -1)

# Evaluate original and shifted regressors
times <- seq(0, 50, by = 2)
orig_values <- evaluate(reg, times)
shifted_values <- evaluate(reg_forward, times)

bbuchsbaum/fmrireg documentation built on March 1, 2025, 11:20 a.m.