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Shift Data Range

Source: R/shift_data.R
shift_data.Rd

Move the range of data channels in a dataframe up or down, while preserving the absolute dynamic range and/or relative scaling across channels. e.g. shift data range to positive values, or shift the mean of the first X number of samples in a recording to zero.

Usage

shift_data(
  data,
  nirs_channels = list(),
  time_channel = NULL,
  shift_to = NULL,
  shift_by = NULL,
  span = 0,
  position = c("minimum", "maximum", "first")
)

Arguments

data

A dataframe.

nirs_channels

A list() of character vectors indicating the column names for data channels to be shifted (see Details).

nirs_channels = list("A", "B", "C")

will shift each channel separately, losing relative scaling.

nirs_channels = list(c("A", "B", "C"))

will shift all channels together, preserving relative scaling.

nirs_channels = list(c("A", "B"), c("C", "D"))

will shift channels A and B together, and channels C and D together, preserving relative scaling within, but not across each group.

time_channel

A character string indicating the time or sample data channel. Must match data column names exactly. Will be taken from metadata if not defined explicitly.

shift_to

A positive or negative numeric value in units of nirs_channels to which the specified data channels will be shifted.

shift_by

An optional positive or negative numeric value by which the data signals can be shifted by a set amount, in units of the nirs_channels.

span

A numeric value in units of time_channel, defining the range over which the position is determined. span = 0 takes the single minimum, maximum, or first value. span = 30 would use the mean of the samples within the lowest, highest, or first 30 units of the time_channel.

position

Indicates how to shift values.

"minimum"

will shift selected channels' minimum values to the specified shift_to value (the default).

"maximum"

will shift selected channels by their maximum values.

"first"

will shift selected channels by their first values.

Value

A tibble of class mnirs.data with metadata available with attributes().

Details

nirs_channels = list() can be used to group data channels to preserve absolute or relative scaling. Channels grouped together in a vector will preserve relative scaling across those channels. Should match column names in the dataframe exactly.

nirs_channels = list("A", "B", "C")

will shift each channel separately. Absolute dynamic range for each data channel is preserved, but relative scaling will be lost between data channels.

nirs_channels = list(c("A", "B", "C"))

will shift all channels together. Absolute dynamic range and relative scaling are both preserved across the group of data channels.

nirs_channels = list(c("A", "B"), c("C", "D"))

will shift channels A and B together, and channels C and D together. Absolute dynamic range and relative scaling are preserved within each group, but not across groups of data channels.

Channels not explicitly specified will not be shifted, but will be passed through to the output dataframe.

If both shift_to and shift_by are defined, only shift_to will be used.