w2l_nest: Reshape Wide Data to Long Format and Nest by Specified...

In mintyr: Streamlined Data Processing Tools for Genomic Selection

Reshape Wide Data to Long Format and Nest by Specified Columns

Description

The w2l_nest function reshapes wide-format data into long-format and nests it by specified columns. It handles both data.frame and data.table objects and provides options for grouping and nesting the data.

Usage

w2l_nest(data, cols2l = NULL, by = NULL, nest_type = "dt")

Arguments

data	data.frame or data.table Input dataset in wide format Automatically converted to data.table if necessary
cols2l	numeric or character columns to transform Specifies columns for wide-to-long conversion Can be column indices or column names Default is NULL
by	numeric or character grouping variables Optional columns for additional data stratification Can be column indices or column names Used to create hierarchical nested structures Default is NULL
nest_type	character output data type Defines nested data object type Possible values: "dt": nested data.table "df": nested data.frame Default is "dt"

Details

The function melts the specified wide columns into long format and nests the resulting data by the name column and any additional grouping variables specified in by. The nested data can be in the form of data.table or data.frame objects, controlled by the nest_type parameter.

Both cols2l and by parameters accept either column indices or column names, providing flexible ways to specify the columns for transformation and grouping.

Value

data.table with nested data in long format, grouped by specified columns if provided. Each row contains a nested data.table or data.frame under the column data, depending on nest_type.

• If by is NULL, returns a data.table nested by name.

• If by is specified, returns a data.table nested by name and the grouping variables.

Note

• Both cols2l and by parameters can be specified using either numeric indices or character column names.

• When using numeric indices, they must be valid column positions in the data (1 to ncol(data)).

• When using character names, all specified columns must exist in the data.

• The function converts data.frame to data.table if necessary.

• The nest_type parameter controls whether nested data are data.table ("dt") or data.frame ("df") objects.

• If nest_type is not "dt" or "df", the function will stop with an error.

See Also

Related functions and packages:

• tidytable::nest_by() Nest data.tables by group

Examples

# Example: Wide to long format nesting demonstrations

# Example 1: Basic nesting by group
w2l_nest(
  data = iris,                    # Input dataset
  by = "Species"                  # Group by Species column
)

# Example 2: Nest specific columns with numeric indices
w2l_nest(
  data = iris,                    # Input dataset
  cols2l = 1:4,                   # Select first 4 columns to nest
  by = "Species"                  # Group by Species column
)

# Example 3: Nest specific columns with column names
w2l_nest(
  data = iris,                    # Input dataset
  cols2l = c("Sepal.Length",      # Select columns by name
             "Sepal.Width", 
             "Petal.Length"),
  by = 5                          # Group by column index 5 (Species)
)
# Returns similar structure to Example 2

mintyr documentation built on April 4, 2025, 2:56 a.m.