fdars (version 0.3.3)

df_to_fdata2d: Convert DataFrame to 2D functional data

Description

Converts a data frame in long format to a 2D fdata object (surfaces). The expected format is: one identifier column, one column for the s-dimension index, and multiple columns for the t-dimension values.

Usage

df_to_fdata2d(
  df,
  id_col = 1,
  s_col = 2,
  t_cols = NULL,
  names = NULL,
  metadata = NULL
)

Value

An object of class 'fdata' with 2D functional data.

Arguments

df

A data frame with the structure described below.

id_col

Name or index of the identifier column (default: 1).

s_col

Name or index of the s-dimension column (default: 2).

t_cols

Names or indices of the t-dimension value columns. If NULL (default), uses all columns after s_col.

names

Optional list with 'main', 'xlab', 'ylab', 'zlab' for labels.

metadata

Optional data.frame with additional covariates (one row per surface). If metadata has an "id" column or non-default row names, they must match the surface identifiers from id_col.

Details

The expected data frame structure is:

• Column 1 (id_col): Surface identifier (e.g., "surface_1", "surface_2")

• Column 2 (s_col): Index for the s-dimension (row index of surface)

• Columns 3+ (t_cols): Values for each t-dimension point (columns of surface)

Each unique identifier represents one surface. For each surface, there should be m1 rows (one per s-value), and m2 t-columns, resulting in an m1 x m2 surface.

Examples

# Create example data frame
df <- data.frame(
  id = rep(c("surf1", "surf2"), each = 5),
  s = rep(1:5, 2),
  t1 = rnorm(10),
  t2 = rnorm(10),
  t3 = rnorm(10)
)
fd <- df_to_fdata2d(df)
print(fd)

# With metadata
meta <- data.frame(group = c("A", "B"), value = c(1.5, 2.3))
fd <- df_to_fdata2d(df, metadata = meta)