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Create a 2D Synthetic Dataset With Class Labels

Source: R/data.R
create_data.Rd

Generates a synthetic two-dimensional dataset and labels each point by whether it lies above or below a piecewise linear boundary. The boundary coordinates can be supplied directly as a matrix/data frame or indirectly via a JSON file containing an array of coordinate pairs, such as the one downloaded from sillysplines().

Usage

create_data(
  coord_filepath = NULL,
  coord = NULL,
  n_samples = 10000,
  type = c("uniform", "normal", "grid"),
  seed = 1835,
  gap = 0,
  r = 0,
  xlim = NULL,
  ylim = NULL
)

Arguments

coord_filepath

A character string specifying a file path to a JSON file containing a list/array of coordinate pairs. Optional if coord is supplied.

coord

A matrix or data frame with two columns (x and y) specifying the boundary coordinates. Optional if coord_filepath is supplied.

n_samples

Integer; number of synthetic 2D points to generate. For type = "grid" the result has floor(sqrt(n_samples))^2 points, and a positive gap removes points, so the result can have fewer rows than n_samples.

type

String; How should the points be generated. Can be either 'uniform' (default), 'normal', or 'grid'.

seed

Integer; Random seed to be used for generating dataset.

gap

Numeric; Value close to 0 defining gap at the boundary, between 0 and 0.2. Points whose vertical distance from the boundary is less than gap are removed.

r

Numeric; Correlation for generating normal sample, between (-0.9, 0.9), default 0.

xlim, ylim

Numeric vectors of length 2 giving the range the points are generated in. Default to the range of the boundary coordinates. Supply these when the boundary does not span the region you want to sample, e.g. xlim = c(-1, 1), ylim = c(-1, 1) for the full sillysplines() canvas.

Value

A data frame with three columns:

x

x-coordinate

y

y-coordinate

class

Binary class label ("Above" or "Below")

Details

Points are labelled using classify_boundary(): a point is "Above" if its y-coordinate is greater than the boundary's y-value at the point's x-coordinate, and "Below" otherwise. Outside the x-range of the boundary coordinates the boundary is held flat at the nearest endpoint.

Examples


coords <- matrix(c(0.2, 0.3,
                   0.4, 0.5,
                   0.6, 0.7), ncol = 2, byrow = TRUE)

df <- create_data(coord = coords, n_samples = 500, seed = 717)
head(df)
#>           x         y class
#> 1 0.5675952 0.5485005 Below
#> 2 0.4260448 0.3920975 Below
#> 3 0.4958921 0.3064470 Below
#> 4 0.3227430 0.6808239 Above
#> 5 0.3820237 0.5811095 Above
#> 6 0.2340915 0.4497553 Above