Streamline S7 class — streamline • fiber

A streamline represents a single fibre tract. It stores three data compartments that mirror the conceptual levels found in tractography file formats:

@points — an \(n \times 3\) numeric matrix whose columns are named "X", "Y", and "Z", holding the ordered 3-D coordinates of the \(n\) points along the tract.
@point_data — a named list of numeric vectors, each of length \(n\), holding per-point scalar attributes (e.g. fractional anisotropy sampled at every point).
@streamline_data — a named list of numeric scalars (length-1 vectors) holding per-streamline attributes (e.g. a tract-level weight or mean FA).

Usage

streamline(points = NULL, point_data = list(), streamline_data = list())

Arguments

points: A numeric matrix with columns "X", "Y", and "Z".
point_data: A named list of per-point numeric vectors.
streamline_data: A named list of per-streamline numeric scalars.

Value

A streamline S7 object.

Methods for standard generics

The following methods are defined for streamline objects:

format(x, ...): Returns a compact character string such as <streamline [10 pts] | point: FA>.
print(x, ...): Prints the formatted string to the console and invisibly returns x.

Additional properties

@n_points: An integer scalar giving the number of points in the streamline (read-only).
@point_attributes: A character vector of the names of the per-point attributes (read-only).
@streamline_attributes: A character vector of the names of the per-streamline attributes (read-only).

Examples

# Create a streamline with 5 points and some attributes
sl <- streamline(
  points = matrix(
    c(0, 0, 0,
      1, 0, 0,
      1, 1, 0,
      1, 1, 1,
      0, 1, 1),
    ncol = 3,
    byrow = TRUE,
    dimnames = list(NULL, c("X", "Y", "Z"))
  ),
  point_data = list(FA = c(0.5, 0.6, 0.7, 0.8, 0.9)),
  streamline_data = list(mean_FA = 0.7)
)
sl@n_points  # 5
#> [1] 5
sl@point_attributes  # "FA"
#> [1] "FA"
sl@streamline_attributes  # "mean_FA"
#> [1] "mean_FA"

# format() and print() methods
format(sl)  # "<streamline [5 pts] | point: FA | streamline: mean_FA>"
#> [1] "<streamline [5 pts] | point: FA | streamline: mean_FA>"
print(sl)
#> <streamline [5 pts] | point: FA | streamline: mean_FA>